HEAT PROCESSING High frequency heating (Vorschau)

ISSN 1611-616X 

VULKAN-VERLAG 

Issue 

3/2011 

Special issue: 

Product Preview to the Hardening 

Colloquium 2011 on pages 288-297 

http://www.heatprocessing-online.com 

High-efficiency quenching and 

tempering plants based on 

comprehensive process expertise 

LOI Thermprocess GmbH - Am Lichtbogen 29 - 45141 Essen / Germany 

Phone +49 (0)201 1891.1 - Fax +49 (0)201 1891.321 

info@loi-italimpianti.de - www.loi-italimpianti.com 

Tenova S.p.A., LOI Italimpianti - Torre Shipping - Via de Marini, 53 - 16149 Genova / Italy 

Phone +39 010 6054807 - Fax +39 010 6054741 

info@loi-italimpianti.it - www.tenovagroup.com

12,000 HARDENING PROCESSES/ YEAR 

20 t WORKPIECE WEIGHT 

1 INDUCTION HARDENING MACHINE 

Visit us at: 

12. – 14.10.2011 Haerterei-Kolloquium 

Wiesbaden/Germany, Building 9, Booth 956 

31.10. – 02.11.2011 HEAT TREAT 

Cincinnati Ohio/USA, Booth 2212 

Liebherr’s Biberach plant has established 

the new standard for the manufacture of 

very large slewing rings and bearing races 

with the successful startup of its new 

EloRing induction hardening system from 

Elotherm. The EloRing efficiently hardens 

workpieces up to 6 meters in diameter, 

weighing up to 20 tons with virtually no 

emissions. 

Its servo-controlled positioning table can 

tilt the workpiece up to 70 degrees from 

horizontal for optimal, uniform quenching 

and simplified workpiece handling. Robust, 

repeatable, reproducible, reliable, and responsible 

– the EloRing by Elotherm. 

MEETING your EXPECTATIONS 

www.sms-elotherm.com

Editorial Reports 

From one exhibition to the other – 

Furnace manufacturers are proving 

their commitment to fuel conservation 

This issue of Heat Processing will be released within a ‘hinge period’ 

between two industrial furnace exhibitions: THERMPROCESS in 

Düsseldorf from June 28 th to July 2 nd and the Härterei-Kolloquium in 

Wiesbaden from October 12 th to 14 th . 

Along with its three ‘cousin exhibitions’ GIFA, METEC and NEWCAST, 

THERMPROCESS broke new records not only in terms of exhibitors (1958 

of them proudly presented their products and most recent developments) 

but also in terms of visitors (79,000 visitors coming from 83 countries). 

A survey held by Messe Düsseldorf after the fair is showing that 80 % of 

these visitors were anticipating capital expenditures over the next couple of 

years. This was reflected through the contacts I had the pleasure to have 

with most CECOF members present in any one of the quartet fairs. Most of 

them were very positive, some even enthusiastic. 

Though it is smaller in size and in geographical coverage, the Härterei-Kolloquium Wiesbaden is 

always representing a busy exhibition and a very informative seminar on heat treatment. It is the 

meeting place, every year, for most of the actors involved in Heat Treatments mainly from the 

German speaking regions. 

Both events are providing windows to the world of the newer technologies and definitely the commitments 

to Energy Savings by the branch of Industrial Furnace Manufacturers. This point is also 

permanently confirmed in the columns of Heat Processing. 

This particular issue is including an article from ‘ERA Technology’, the consultant appointed by the EU 

Commission in a consortium with ‘BIO Intelligence Service’to assess ‘DG ENTR Lot 4’ on ‘Industrial and 

Laboratory Furnaces and ovens’ within the framework of the so-called ‘EuP Directive’ (2009/125/EC) 

for the Eco design of Energy using Products. This paper presents in length the purpose, advantages 

and eventual threads that this Directive could represent on our branch. In reality, we, at CECOF, have 

always considered this challenge more as a definite benefit: Our members are proving throughout 

these exhibitions and through the pages and issues of this magazine that they master the technologies 

for energy efficiency and that they have the willingness to share them with their customers. We 

hope that the regulations that will come out of this ‘lot 4’ will be additional incentives to our customers 

to ‘buy efficiency’ and will – by no means – represent sterile additional burden on our designers. 

Originally, the article of ERA/BIO was planned to appear in the columns of the ‘CECOF Corner’ but 

its length would not make it fit. Therefore, exceptionally, it will be no CECOF corner in this issue. 

I wish you an excellent reading of the very interesting articles of this magazine. 

Michel Debier 

President of CECOF 

HEAT PROCESSING · (9) · ISSUE 3 · 2011 217

Official publication of 

TABLE OF CONTENTS 

Issue 3 · August 2011 · Volume 9 

www.heatprocessing-online.com 

INTERNATIONAL MAGAZINE FOR INDUSTRIAL FURNACES · HEAT TRATMENT PLANTS · EQUIPMENT 

Reports 

HEAT TREATMENT 

Holger Kehler, Dominikus Schröder, Wolfram Schupe 

High-efficiency quenching and tempering plants 

based on comprehensive process expertise.............. 243 

244 

Modern control centre – High-efficiency quenching 

and tempering plants 

Olaf Irretier, David Salerno 

Advantages for nitrocarburizing processes with post 

oxidation in continous furnaces ......................... 249 

BURNER & COMBUSTION 

Daniel Cardoso Vaz 

Relations between global recirculation ratio and 

area ratio in combustors fired with jets ................. 253 

STANDARDS & GUIDELINES 

Paul Goodman, Chris Robertson 

Eco-design study of industrial and laboratory furnaces 

and ovens ............................................. 256 

Eco-design study of industrial and laboratory 

furnaces and ovens 

257 

INDUCTION TECHNOLOGY 

Ovidiu Peşteanu 

Simplified calculation of molten metal free surfaces 

in electromagnetic fields Part I: Mathematical model ..... 259 

Alexander Ulferts, Frank Andrä 

Online frequency adjustment for energy optimization 

of induction hardening processes ....................... 263 

Victor Demidovich, Pavel Maslikov, Evgeniy Grigoriev, 

Vladimir Olenin, Irina Rastvorova 

Precise induction heating of Ti and Zr billets ............ 266 

297 

HK-SPECIAL: Read all about the latest products 

and news of the branch 

MEASUREMENT & PROCESS CONTROL 

Karl-Michael Winter 

Impact of measurement errors on the results of 

nitriding and nitrocarburizing treatments ............... 271 

Džo Mikulovic´, Dragan Živanovic´, Florian Ehmeier 

Reference measurements in gas carburizing 

atmospheres: part 2 ................................... 279 

220 

HEAT PROCESSING · (9) · ISSUE 3 · 2011

News 

Trade & Industry 224 

Diary Dates 232 

Events 233 

Personal 237 

Book Review 240 

Basics 

PRINCIPLES OF HEATING PROCESSES 

Edition 16: High frequency heating 285 

HK 2 011 

product preview 

Find out more about the latest product 

highlights and services of the exhibitors 288 

Profile 

COMPANIES PROFILE 

ELINO INDUSTRIE-OFENBAU GMBH 298 

Business Directory 

I. Furnaces and plants for industrial 

heat treatment processes 300 

II. Components, equipment, production and 

auxiliary materials 309 

III. Consulting, design, service and engineering 317 

IV. Trade associations, institutes, universities, organisations 318 

V. Exhibition organizers, training and education 319 

www.heatprocessing-directory.com 

Columns 

Editorial 217 

Index of Advertisers Cover page 3 

Imprint Cover page 3

Hot Sh ots

Inductive "Black annealing" 

Longitudinally welded stainless steel pipes will be diffusion and recrystallization 

annealed under normal atmosphere by a medium frequency induction heating 

system. (Source: SMS Elotherm GmbH / Sosta GmbH & Co. KG)

News 

TRADE & INDUSTRY 

Trade & Industry 

Seco/Warwick establishes subsidiary 

in Germany 

Honeywell launches new technical centre 

in Germany 

The facility located in Munich 

(Germany), will provide German 

gas detection customers 

with additional local services 

such as customer support, a 

state-of-the-art training centre 

and centralized repair and 

equipment maintenance services. 

The site will also house 

gas detection to deliver new 

product solutions designed to 

meet specific regional needs. 

Building: 1,800 m 2 facility 

shared between Honeywell 

Gas Detection (Honeywell 

Analytics and BW Technologies 

by Honeywell) and Honeywell 

Scanning and Mobility. 

The SECO/WARWICK Group 

established a new subsidiary 

in Germany operating under 

the name of SECO/WARWICK 

GmbH and having its registered 

office in Stuttgart, Germany. 

The main objective is 

to increase sales of products 

manufactured by the atmosphere 

and vacuum furnace 

segment of the Group, with 

focus on low-pressure carburizing 

with pre-nitriding using 

PreNitLPC ® and FineCarb ® 

technologies. The subsidiary 

will be managed by Thomas 

Wingens, who has 25 years 

of experience in the heattreatment 

industry. 

The German subsidiary will 

offer furnaces produced by 

SECO/WARWICK S.A. and 

SECO/WARWICK ThermAL 

S.A. and will provide technical 

assistance to customers in 

Germany, Austria, the Netherlands, 

Switzerland, Liechtenstein 

and Slovenia. According 

to the company, its goal is to 

intensify sales and expand its 

share in the German market. 

Andritz supplies rolling mill for production of 

carbon steel to South Korea 

project engineering and R&D 

teams, providing German customers 

with locally focused 

product innovation and 

bespoke solutions designed 

to meet specific customer 

needs. Local product design 

teams will help Honeywell 

The resource will include 

three fully equipped training 

suites, where customers 

can gain knowledge on a 

wide range of topics; from 

the basics of gas detection to 

master classes on aspects like 

product certification. 

International technology 

Group ANDRITZ has received 

an order from the South 

Korean carbon steel producer 

Dongkuk Industries Co., Ltd. 

to supply a 6-high rolling mill 

with an annual capacity of 

169,000 t. Start-up is scheduled 

for the end of 2012. 

The scope of supply includes 

the mechanical and complete 

electrical equipment for the 

plant, which is to produce 

low, mid, and high carbon 

steel with thicknesses ranging 

from 0.4 mm to 10.0 

mm and a maximum width 

of 650 mm. This order confirms 

the long-standing good 

partnership of ANDRITZ and 

Dongkuk Industries which has 

been operating an S6-high 

rolling mill and a roll grinding 

machine from ANDRITZ MET- 

ALS successfully. 

Tenova opened its office in Vietnam 

Elotherm received an order for an induction 

hardening system 

Elotherm received an order 

for an automated induction 

hardening system. A U.S.- 

based manufacturer will use 

the turnkey process solution 

to make high-performance 

powertrain components. The 

system will enable reliable 

hardening of superior-quality 

parts with more than twice 

the throughput of conventional 

equipment. It will feature 

Elotherm’s patented 

inductor designs for hardening 

rotational parts as well 

as the company’s patented 

energy-monitoring technology 

for precise, real-time 

control of the manufacturing 

process. 

Commissioning is scheduled 

for 2012. 

Tenova Group officially 

opened (May 2011) its representative 

office in Ho Chi 

Minh City, Vietnam, with an 

inauguration ceremony held 

at the Legend Hotel. The ceremony 

was attended by more 

than a hundred delegates representing 

different Vietnamese 

steel companies as well as 

officials of the steel industry 

in Vietnam. A large delegation 

of Tenova officers lead 

by Mauro Bianchi Ferri, Vice 

President of Tenova Metal 

Making, and by Giuliano 

Fanutti, Chief Representative 

Officer, did the honors of the 

event. The inauguration was 

done in the presence of the 

Italian Ambassador Lorenzo 

Angeloni, who welcomed the 

establishment of the Tenova 

representative office into the 

Italian business community 

of Vietnam. Mr. Tam, Secretary 

General of Vietnam Steel 

Association, highlighted the 

strategical role of Tenova in 

the steel industry in Vietnam. 

Appreciation of Tenova technologies 

was expressed by 

224 



News 

Mr. Thai, President of Thep 

Viet and Pomina Group that 

have selected Tenova for the 

supply of equipment in their 

two steel factories. The more 

recent Pomina project will 

be the largest steel plant in 

Vietnam with production of 1 

million t of steel/year. Several 

projects by Tenova are being 

implemented in the areas of 

steelmaking, reheating furnaces, 

cold rolling mill processing 

lines and roll grinders 

recognizing the Vietnam steel 

industry committed to value 

added solutions. Finally he 

reaffirmed the commitment 

of Tenova to the growing 

market in Vietnam and in the 

surrounding ASEAN countries. 

Level 2 process control and 

automation systems for the 

furnace. This project will mark 

the first installation on a new 

furnace of Tenova Core’s 

Level 2 system that includes 

an advanced model predictive 

control engine. The new Level 

2 system heats the charge at 

an “optimum cycle” predetermined 

for each type of 

material for the complete 

range of furnace production 

rates. 

Bodycote opens heat-treat facility in Mexico 

Gerdau Ameristeel orders walking-beam furnace 

Tenova Core has been contracted 

by Gerdau Ameristeel 

to design and supply a 

140 t/h walking-beam reheat 

furnace. The furnace will be 

installed at Gerdau’s Calvert 

City, Kentucky, U.S.A., facility 

in 2012. It will replace an 

existing furnace and will be 

used to efficiently and uniformly 

heat billets for processing. 

The furnace will feature a 

combustion system equipped 

with Tenova’s TSX low-NO x 

recuperative burners for reliable 

temperature uniformity 

as well as emissions control. 

Tenova Core will also design 

and supply the Level 1 and 

Bodycote announced the 

planned opening of a new 

vacuum heat-treatment facility 

in northwest Mexico. 

The facility will provide outsourced 

specialist processing 

support to major aerospace 

and power-generation suppliers 

in the area. The new plant, 

located in the city of Empalme 

in the State of Sonora, is a 

result of Bodycote’s recently 

signed long-term agreement 

with Trac Precision, a key 

supplier to Rolls-Royce and 

Siemens. Under this agreement, 

Bodycote will support 

Trac‘s Mexico operations with 

vacuum brazing and heat 

treating. 

The facility, which is scheduled 

to open in the third 

quarter of 2011, will be a 

more cost-effective option for 

other aviation manufacturers 

within the region, enabling 

them to provide complete 

processing without transporting 

parts back to the U.S. The 

Innovative 

Heat Treatment Vacuum Solutions 

If you are looking for a new vacuum system for your 

heat treatment tasks, check out the innovative 

vacuum solutions provided by Oerlikon Leybold 

Vacuum! Our products excel with highest robustness 

and extreme compactness, combined with 

lowest power consumption and noise emission. 

Please contact us or visit us at 

67 th Härterei-Kolloquium, Wiesbaden 

October 12-14, 2011. Hall 3, Booth 336. 

Oerlikon Leybold Vacuum GmbH 

Bonner Strasse 498 

D-50968 Köln 

T +49 (0)221 347-0 

F +49 (0)221 347-1250 

info.vacuum@oerlikon.com 

www.oerlikon.com/leyboldvacuum 


News 


Mexico site will maintain full 

aerospace accreditation and 

prime approvals supported by 

Nadcap and AS9100. In other 

news, Bodycote announced 

the signing of a 10-year 

renewal contract with Rolls- 

Royce to provide thermalprocessing 

services in the 

U.K. Bodycote will provide 

Rolls-Royce with heat treatment, 

hot isostatic pressing, 

thermal spray coatings and 

metal joining. 

ble even with high ambient 

temperatures or high solar 

radiation, according to the 

company. BASF provides the 

insulation material at nominal 

compressive strengths of 

300 and 600 kPa. The product 

is particularly suitable for 

insulating hot water tanks, 

insulation applications with 

hot water that are exposed to 

pressure and moisture, and 

for various insulation applications 

in solar technology. 

Ipsen presence is customer focused 

Edmonton Exchanger orders car-bottom furnace 

Ipsen, based in Kleve, is now 

moving closer to their customers 

by setting up a customer 

service center in the 

town of Filderstadt, located in 

Southern Germany. From 1 st 

May more than ten employees 

from “Ipsen Service Süd” 

will look after customers in 

Southern Germany. 

equipment but also for equipment 

from other suppliers. 

There is nothing more annoying 

and costly than a timeconsuming 

interruption in a 

production process; that’s 

why Ipsen Service Süd now 

offers a 24/7 emergency service. 

New service vans were 

Can-Eng Furnaces International 

delivered a 130 t carbottom 

furnace to Edmonton 

Exchanger, a manufacturer 

of heavy-walled steel cylinder 

and dished head assembly 

units located in Edmonton, 

Alberta (Canada). The furnace, 

which is designed for 

stress relieving and reheating 

at temperatures up to 

2,000 °F, is to be operated 

as a single 55-foot chamber 

or two independent heating 

chambers (24 feet and 31 

feet) separated by an inner 

door. The dual door and twocar 

assembly gives Edmonton 

Exchanger the flexibility to 

utilize a smaller heated chamber 

as dictated by customer 

requirements. 

The decision to establish a 

branch in Baden-Württemberg 

seemed more than sensible 

as there are more than 

200 customers situated in 

this region. Customers can 

now look forward to a faster 

response from our customer 

service - not only for Ipsen 

provided for our experts and 

a comprehensive spare parts 

stock (500 m²) established, 

so that a quicker reaction on 

demand is possible. Furthermore, 

scheduled installation 

servicing will also be carried 

out by personnel from Filderstadt. 

Shandong Steel Mill uses oxy-fuel technology 

Praxair (China) Investment 

Co. Ltd. signed a combustion 

equipment contract with 

Shandong Guangfu Group 

to implement Praxair’s proprietary 

oxy-fuel technology. 

Under the contract, one of 

Praxair’s gas injection systems, 

including three oxygen 

gas injectors and other 

related equipment, will be 

installed at the 100-t electric 

arc furnace (EAF) at Shandong 

Guangfu Group’s steel 

mill in Shandong province. 

Compared with conventional 

lance systems, Praxair’s technology 

enables customers 

in the steel and nonferrous 

metal industries to experience 

improved operational 

safety and environmental 

protection, cost savings and 

increased productivity. 

Weiqiao Aluminum orders aluminum-melting 

furnaces 

Insulation from BASF with an effective 

up to 105 °C 

A key feature of insulation 

from BASF, Florham Park, 

N.J., is its heat-distortion 

temperature of up to 105 °C 

(221 °F), which is the application-limit 

temperature. The 

new material, called Styrodur 

HT, consists of extruded polystyrene 

rigid-foam panels. 

The high temperature limit 

makes the foam suitable for 

applications exposed to high 

temperatures that require 

high compressive strength, 

low water absorption, resistance 

to rot and good insulation 

performance. Styrodur 

HT stays dimensionally sta- 

Bricmont Inc., an Inductotherm 

Group Company, was 

awarded a contract to supply 

eight high-productioncapacity 

round top-charge 

aluminum-melting furnaces 

and eight rectangular, tilting 

holding furnaces for Weiqiao 

Aluminum and Electricity 

Company’s new production 

facility in China’s Shandong 

Province. Bricmont will provide 

engineering, materials, 

procurement and field services 

for the furnaces, while 

Inductotherm Group China 

will provide local materials, 

installation and support services. 

The installation will include 

regenerative burners, electromagnetic 

stirring, in-bath 

metal refining and advanced 

controls. When commissioned 

in late 2012, it will be 

one of the largest-capacity 

aluminum casting centers in 

China. 

226 


THE POWER OF PARTNERSHIP 

Up to 1,850°C : > Electric Heating Systems „by MoSi 2 

“ 

> Thermal Insulation „by PCW“ 

> Temperature Measuring „by Ceramics“ 

M.E.SCHUPP ® , founded in 1996, now 36 dedicated employees 

in six teams and around 7 million euros in annual sales revenue. 

Specialist in ceramic/metallic “key components” for industrial and 

laboratory kilns and furnaces up to 1,850°C. M.E.SCHUPP ® ’s 

work is innovative, productive and economically sound. It focuses 

on the client and is well organized. For many years with production 

partners from Japan and Asia and with its own production facility 

in Aachen, Germany. 

What we do is “tangible”, meets high engineering standards and is 

very competitive. 

We‘re looking for people to join us. 

1. International Field Sales Eng. (m/f) 

2. Assistant to the Head of Technology, 

Production and Project Engineer (m/f) 

You know what‘s happening in the world and on the market. You 

appreciate the opportunity for further training. You are smart, attentive, 

hard-working, tough, resilient, and open. You love technology, 

like people, and enjoy good communication. You work with targets, 

both in a team and on your own. Good results and satisfied clients 

are the basis. 

You have an excellent command of both written and spoken English 

and have a confident and forthcoming manner. You know your 

way around business situations and act with commercial principles 

in mind. 

1. As an experienced, successful and convincing sales 

engineer, you consult and acquire. 

Be it personally, by e-mail, or by phone. You cultivate our clients 

and partners, and create new contacts based on our CRM-files. 

You like to travel, have an international perspective in your business 

trips, and are a skilled negotiator. 

You will represent M.E.SCHUPP ® with all the opportunities we 

have, and will pave the way to a business relationship that is beneficial 

for both parties. You will receive all the support you need for 

this from the team. 

You will be in contact with works managers, purchasers, technicians, 

owners, and company directors, and these may be also from 

other countries and cultures. You will conclude discussions with 

clients by successfully closing the deal. You keep a track of offers, 

projects, and deadlines consistently with the back-up team in Aachen/Germany, 

and are up to speed with modern IT and software 

such as MS Office a.o. 

We work with target clients in Europe, Asia, India, America and 

other regions, and support clients and partners, including at national 

and international trade fairs and in “online sales”. 

2. As an assistant to the Head of Technology/Technical 

Director, you will have studied ceramics, PM (CIM, MIM), materials 

engineering or industrial kiln/furnace technology. You may also 

be a graduate. Practical previous training in fields such as mechatronics, 

electrical engineering, process engineering or similar would 

be advantageous. A good command of AutoCAD or comparable 

software would be of benefit. You enjoy QA, development, production, 

and engineering projects for clients. 

M.E.SCHUPP ® : Income in line with performance, select benefits, a 

modern job with opportunities. A human approach at a high performance 

level. Specialist markets with tradition, a future and healthy 

growth! The City of Aachen, located at the Germany-Belgium- 

Netherlands triangle, is an attractive place to live and work, and the 

RWTH is an internationally leading technical top university. 

Please submit your application complete with relevant application 

documents, your salary expectations and an indication of the earliest 

time when you could begin working. We look forward to receiving 

your application. 

M.E.SCHUPP ® Industriekeramik GmbH & Co. KG 

Neuhausstraße 4-10 

52078 Aachen / Germany 

E-Mail : michael@schupp-ceramics.com 

www.schupp-ceramics.com

News 


Tenova Goodfellow recognized with award for 

new detection system technology 

At the recent Consulting 

Engineers of Ontario Annual 

General Meeting & Awards 

Banquet, Tenova Goodfellow 

Inc. (TGI) was recipient of an 

Award of Excellence, receiving 

acclamation from Canadian 

Engineering peers for 

the installation and commissioning 

of their Slop Detection 

System (SDS) Technology 

on five (5) BOF vessels at (Riva 

Group) ILVA, Taranto, Italy. 

Tenova Goodfellow’s Slop 

Detection System (SDS) Technology 

uses lance vibration 

analysis with real-time alerts to 

give operators advance warning 

of the onset of a slop and 

a measurement of slop severity. 

The system is designed 

to provide direct feedback 

control of lance position and 

oxygen flow rate, for rapid 

Second Corex C-3000 plant at Baosteel in China 

is started 

The Corex C-3000 Module 

02, installed with a nominal 

production capacity of 1.5 

million t of hot metal per 

year, was started up at the 

steelworks of Shanghai Baosteel 

Pudong Iron and Steel 

Co. Ltd. (Baosteel) in Luojing, 

mitigation of the effects of 

a slop. Accepting the award 

on behalf of TGI was Vittorio 

Scipolo, Manager, R&D “The 

SDS technology is one of four 

innovative modular solutions 

in Tenova’s comprehensive i 

BOF ® Technology, offering 

BOF steelmakers great opportunity 

to reduce their costs 

and increase their competitiveness. 

For ILVA, Taranto, the SDS 

technology accurately provided 

early indication for 

87 % of the slopping heats 

observed. The automation 

of the lance flow and height 

resulted in increased productivity, 

improved yield as well 

as reductions in lost time 

associated with equipment 

cleanup and reduced atmospheric 

emissions. 

near Shanghai, China. The 

new plant incorporates all of 

the experience acquired from 

the operation of the first 

Siemens VAI-supplied Corex 

C-3000 Module 01 at the 

same site, which commenced 

operation in November 2007. 

Baosteel‘s decision 

to install a second 

Corex plant underlines 

the company‘s 

commitment 

to cost-effective 

and environmentally 

friendly iron 

production that 

fully meets the 

strict emission regulations 

imposed 

by the Shanghai 

municipal government. 

The order for the 

second Corex 

module, which is 

basically identical 

in design to the 

first module, was received 

in December 2007. Siemens 

VAI provided the complete 

process technology, and 

engineered and supplied key 

equipment and components. 

This included oxygen burners, 

screw conveyors for the coal 

and direct-reduced iron, two 

Gimbal Top charging systems 

(one for the charging of burden 

into the reduction shaft 

and one for the charging of 

coal into the melter gasifier), 

gates at the dust-recycling 

systems, electrical equipment 

for Level 1 and Level 2 automation 

and core instrumentation. 

A special design feature of 

the new Corex module is the 

so-called aerial gas distribution 

(AGD) system. AGD supports 

the injection of reduction 

gas through the bustle 

system into the Corex shaft 

by means of an additional 

gas distribution into central 

zone of the reduction shaft. 

This further enhances shaft 

performance in that a more 

homogeneous reduction of 

the burden is achieved, leading 

to an increased productivity. 

The top gas from the 

two Corex plants is used for 

the generation of electrical 

energy and for heating 

applications throughout the 

Baosteel steelworks. Since 

October 2010, the previously 

installed Corex Module 01 

has been in stable operation 

with an overall availability of 

94 % and high productivity 

rates. The specific hot-metal 

costs and the consumption 

figures attained their lowest 

levels since the start-up of 

the plant. 

voestalpine Austria Draht relies on Ebner 

technology 

Voestalpine Austria Draht 

has ordered two HICON/ 

H 2 

® workbases from EBNER 

Industrieofenbau for the 

plant located in Bruck an der 

Mur (Austria). The investment 

comprises the dismantling of 

the old facility and the turnkey 

installation and commissioning 

of the new one. 

The customer placed special 

emphasis on the implementation 

of the state-of the-art 

technology. The measuring 

and regulating technology as 

well as the electrics will be 

upgraded to the latest technical 

standard and installed in 

the existing one. The facility is 

scheduled to start production 

in December 2011. 

V & M Star is building tube plant in Ohio 

V & M Star is building a 

new seamless tube plant in 

Youngstown, Ohio, located in 

Mahoning County between 

Pittsburgh and Cleveland, 

U.S.A. Commissioning of the 

facility, which includes a hot 

rolling mill, is scheduled for 

the first half of 2012. After 

its completion, the plant 

will be capable of producing 

450,000 t per year of highquality 

seamless tubes within 

a diameter range of 60.3 mm 

to 180 mm with tolerances 

and mechanical properties 

according to international 

standards. 

The hot rolling mill consists 

of an FQM-Elongator, an 

extracting block (EXB) and a 

stretch reducing block (SRB). 

Construction is being carried 

out by Danieli Centro Tube, 

a member of Danieli-Group, 

while Friedrich Kocks will supply 

equipment. V & M Star, 

which belongs to Vallourec, 

produces seamless tube in 

North America. 

228 



News 

ThyssenKrupp Steel Europe invests millions in hot 

strip production 

ThyssenKrupp Steel Europe 

AG is to invest around € 300 

million in its hot strip mills 

in Bochum and Duisburg, 

Germany. The investments 

will help the steel producer 

strengthen its position as 

technology leader for premium 

flat-rolled carbon steel 

products. The modernization 

will also secure sites and jobs 

in the Rhine-Ruhr area. 

Hot-rolled strip is the basis 

for all ThyssenKrupp Steel 

Europe’s flat steel products. 

The company operates four 

hot strip mills with a total 

annual capacity of around 

15 million t. Hot strip mills 

1 and 2 are located at the 

Duisburg site, along with a 

casting-rolling line that also 

produces hot-rolled. Hot strip 

mill 3 is in Bochum. To produce 

hot strip, steel slabs are 

rolled into thin strip in a series 

of mill stands at temperatures 

of more than 1,000 °C. The 

material is either used by customers 

directly or further processed 

at ThyssenKrupp Steel 

Europe. 

Among other things, the hot 

strip mills now to be modernized 

produce lightweight 

steels for the automotive 

industry, starting material for 

tinplate – which is 100 % 

recyclable and is used to 

make food and beverage cans 

– as well as steels for oil and 

gas pipelines. Other products 

include starting material for 

electrical steel, which is used 

for example in wind turbines, 

in hybrid engines for cars 

and transformers, where it 

ensures extremely efficient 

power transmission. For these 

steel grades, precision dimensions 

and consistent, carefully 

controlled properties along 

the entire length of the strip 

are of key importance. 

One of the focuses of the 

investment program is hot 

strip mill 1, which has an 

annual capacity of around 

three million metric tons. The 

mill will be equipped with 

profile, contour and flatness 

control systems to ensure 

highly consistent and precise 

dimensions over the full 

length and width of the hot 

strip. The strip cooling system 

will also be replaced. The 

cooling process exerts a major 

influence on the properties of 

the steel, such as its strength 

and formability. The furnaces 

used to heat the steel slabs 

to rolling temperature will be 

fitted in part with new burners. 

These will reduce heating 

times and require less energy. 

The upgrade program also 

includes new roll drives and a 

new computer control system 

for the entire mill train. 

A new accelerated cooling 

system is currently being 

installed on hot strip mill 2 at 

the Duisburg-Beeckerwerth 

plant. Among other things, 

this will permit ThyssenKrupp 

Steel Europe to expand its 

range of high-strength steels 

for oil and gas pipelines. 

Additional investments will 

go into a new computer control 

system for the roughing 

and finishing mills and into 

equipping further roll drives 

with new, large motors. 

The transportation and storage 

facilities for finished 

hot-rolled coils will also be 

replaced. At hot strip mill 3 in 

Bochum, a new cooling line is 

to be installed for more exact 

temperature control as well 

as new rolling equipment for 

enhanced dimensional accuracy. 

Visit us 

at the HK in Wiesbaden, 

hall 9, booth 936! 

© appeal 043 107 

Hardness which pays off 

The technology of ALD´s ModulTherm ® heat treatment system for hardening and case hardening of 

serial parts has been successfully used for many years, worldwide. The new model ALD ModulTherm ® 2.0 

offers optimum process fl exibility, reduced manufacturing costs as well as environmental compatibility. 

First class service allows for smooth continuous operation. 

For more information please contact us! 

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Wilhelm-Rohn-Strasse 35 

63450 Hanau, GERMANY 

Phone +49 (0) 6181 307-0 

Email info@ald-vt.com 

Internet www.ald-vt.com

News 


ThyssenKrupp Steel Europe 

has already invested € 180 

million in expanding hot strip 

mills 2 and 3 since 2006, creating 

additional capacities to 

handle two million tons of 

slabs per year from ThyssenKrupp’s 

new steel mill in Brazil. 

Inductotherm and Powerit Solutions improve 

energy efficiency of customers 

Inductotherm Corp. and Powerit 

Solutions announced an 

agreement that underscores 

the companies’ dedication to 

improving the operations and 

energy efficiency of their customers 

in the metals industry. 

The two businesses will work 

closely to take Powerit’s Spara 

system, an advanced energymanagement 

technology, to 

the market. Inductotherm will 

make Spara available to its 

customers, and the two companies 

will work together to 

implement the best energymanagement 

strategies and 

integrate the technology. 

Powerit’s Spara technology, 

an integrated hardware and 

software product, plugs businesses 

into the smart grid so 

that facilities can use energy 

more efficiently and take 

advantage of utility incentive 

programs and rate structures. 

For foundries, the most 

widely used Spara-enabled 

strategy is demand control, 

which involves deciphering 

how and where costly energy 

spikes occur, then making 

precisely timed load reductions 

to avoid those spikes to 

take advantage of lower-rate 

periods. 

pany is currently implementing 

a large-scale program to 

expand its production capacities. 

As part of this program 

Siemens VAI already received 

an order to supply a rolling 

mill for stainless steel bar 

and light sections (180,000 t/ 

annum). The new AOD converter 

will have a capacity of 

245,000 t of liquid steel per 

year, which will enable Viraj 

Profiles Ltd. to substantially 

increase both the volume and 

efficiency of stainless steel billet 

and bloom production in 

Tarapur. It will then be able to 

supply most of the new and 

existing rolling mills with billets 

from its own production. 

Siemens VAI will be responsible 

for the engineering of 

the AOD converter, which 

will have a tapping weight of 

55 t. It will also supply core 

components, including the 

trunnion ring, tilting drive, 

valve station, rotating inlet, 

injection nozzles, top lance 

and a combined lance and 

extraction hood carriage. The 

special features of the plant 

include the suspension system, 

a traversing extraction 

hood and top lance, as well 

as individual nozzle control. 

The order also includes the 

Level-2 automation system 

for the converter tilt drive, the 

blowing lance and the bottom 

blowing system. Siemens 

VAI will also supply the process 

automation, including 

the Simetal AOD optimization 

system and the steel expert 

process models. Siemens Ltd. 

India will handle some of the 

local manufacturing for the 

project. This includes supplying 

the trunnion ring and 

parts of the basic automation 

system for the AOD converter 

as well as supervising installation 

and commissioning. 

Siemens VAI Metals supplies converter for its 

plant in India 

Siemens VAI Metals Technologies 

won an order from 

the stainless steel producer 

Viraj Profiles Ltd. to supply 

an AOD (argon-oxygen 

decarburization) converter 

for its plant located in Tarapur, 

Maharashtra, India. The 

new converter will enable the 

company to expand the stainless 

steel output required for 

its rolling mills. The project is 

scheduled to be completed by 

mid-2011. 

Viraj Profiles Ltd. is India‘s 

largest producer of stainless 

steel long products. The com- 

ArcelorMittal orders twin-ladle furnace 

Siemens VAI Metals Technologies 

has received an 

order from ArcelorMittal Bremen 

GmbH to supply a 300 t 

twin-ladle furnace. The plant 

will be constructed in the 

works of ArcelorMittal Bremen 

GmbH to replace the 

two conditioning stands currently 

used for treating liquid 

steel. This will substantially 

reduce steel treatment costs. 

The project has a volume of 

several million euros. The new 

ladle furnace is scheduled to 

come into operation in February 

2012. 

The twin-ladle furnace will be 

installed directly downstream 

of the LD converter in the 

ArcelorMittal Bremen GmbH 

Steelworks and be designed 

to ensure the best possible 

logistic links to other parts of 

the plant and reduce crane 

movements to an essential 

minimum. A cross transfer 

ladle car will link up to the 

existing RH vacuum treatment 

unit. In addition, an 

ingot casting plant for producing 

special products will 

be served via a transverse 

track. 

In future, it is intended to 

use the ladle furnace to 

treat as many melts as possible 

– some 3.5 million t 

of crude steel per annum. 

Its main task will be to heat 

the melt, achieving a heating 

rate of 4 °C per minute for a 

30 min period of treatment. 

Optimum control of the electrodes 

will be ensured by the 

Simelt AC electrode control 

system. The tapping temperature 

on the LD converter can 

be reduced by between 40 

and 60 °C, which will lower 

the consumption of refractory 

material in the converter. 

The ladle furnace will 

increase the efficiency of the 

ladle treatment facility, and 

reduce operating costs. The 

230 


News 

DIARY 

232 


TRADE & INDUSTRY / EVENTS 

News 

ladle furnace will also be able 

handle fine alloying work and 

blowing operations, which 

had previously taken place in 

the conditioning stands. The 

equipment supplied for this 

purpose will include two sixtrack 

wire feeding machines. 

Events 

GIFA, METEC, THERMPROCESS, NEWCAST 

2011: Right on target with new exhibitor and 

visitor records 

Dongbu Special Steel orders another 

HICON/H 2 

® annealing facility for steel wire 

Dongbu Special Steel Co., 

Ltd. of Korea has ordered 

another HICON/H ® 2 bell 

annealer facility from EBNER 

for its Pohang works. The 

new facility will double the 

HICON/H ® 2 annealing capacity 

at Dongbu Special Steel‘s 

steel wire works. 

The expansion phase comprises 

three HICON/H ® 2 

workbases, two heating bells 

and a cooling bell as well as 

new pressure control systems 

for hydrogen, nitrogen and 

fuel gas. Each workbase can 

Nitrex Metal supplies nitriding systems 

Nitrex Metal will supply 

turnkey nitriding systems 

to a manufacturer of OE 

and aftermarket automotive 

parts for its piston rings 

facilities in Europe. The pair 

of NX-1015 systems, which 

include Nitreg®-S technology 

for “zero white-layer” 

nitriding, is expected to help 

the company meet its increasing 

production output while 

maintaining the dimensional 

stability of the stainless steel 

and cast iron piston rings. The 

systems are scheduled to be 

delivered in the second half 

of 2011. 

Andritz receives major order for new stainless 

steel plant in Malaysia 

International technology 

Group Andritz has received 

an order from Bahru Stainless 

SHN BHD, a joint venture 

between Acerinox SA., Spain, 

and Nisshin Steel, Japan, to 

supply an annealing and pickling 

line for cold-rolled stainless 

steel strip. Total order 

value is approximately € 65 

million. Start-up is scheduled 

for the end of 2012. Andritz 

accommodate a net charge 

of max. 48 t. With a max. 

annealing temperature of 

810 °C (1490 °F), the facility 

is perfect for cold-heading 

grades and ball bearing steel. 

The new facility will be integrated 

into the existing control 

and central operating 

systems. Full workbase/bell 

compatibility the six existing 

HICON/H ® 2 workbases 

is guaranteed. The facility is 

scheduled to start production 

in April 2012. 

Metals’ scope of supply comprises 

the complete mechanical 

equipment as well as the 

furnace and pickling section, 

the inline skin pass mill, electrical 

and automation equipment, 

and erection of the 

complete plant. The plant will 

produce cold-rolled strip in 

the thickness range from 0.25 

to 2.5 mm and up to 1,600 

mm wide. 

The quartet of technology 

trade fairs GIFA, METEC, 

THERMPROCESS and NEW- 

CAST closed right on target 

after five trade fair days in 

Düsseldorf. The trade fairs 

posted new records both in 

terms of exhibitors and visitors. 

1,958 exhibitors from 

throughout the world met 

with 79,000 visitors from 83 

countries. With these results 

the trade fairs impressively 

confirmed their standing as 

the leading trade fairs in their 

sectors. 

In particular, the high percentage 

of both international 

exhibitors and visitors evidenced 

just how popular the 

trade fairs are globally. The 

share of international visitors 

was up again over the previous 

events: Over 54 % of 

visitors travelled to Düsseldorf 

from abroad, especially from 

India, Italy, France, Austria 

and the USA. The long journey 

proved worthwhile because 

nearly all visitors voiced great 

satisfaction with the trade 

fairs (98 %) and regard the 

aim of their visit 

fulfilled (97 %). 

Also outstanding 

is the number 

of experts from 

top management. 

Some 80 % of 

visitors plan capital 

expenditure over 

the next two years 

– and the majority 

of them prepare 

for these at GIFA, 

METEC, THERM- 

PROCESS and 

NEWCAST. However, 

more often 

than not, even 

concrete business 

deals were concluded 

at the four 

trade fairs under 

the umbrella brand “The 

Bright World of Metals”. For 

instance, at the trade fair a 

US$ 54 million deal was concluded 

between a German 

casting machinery manufacturer 

and the Uzbek railway 

company. A Dortmund-based 

induction furnace producer 

also reported the sale of one 

of the world’s most powerful 

melting furnace to an Indian 

steel producer. 

The promoter associations 

VDMA and bdguss reported 

that their innovative member 

companies were highly 

delighted with the wide representation 

of the machinery 

market on the one hand, 

and the high internationality 

of well-informed visitors, on 

the other, who came to the 

event with specific purchasing 

intentions. Summing up 

the response of the represented 

member companies, 

Dr. Gutmann Habig, the 

responsible General Manager 

at VDMA, said: “After overcoming 

the economic crisis 

this, the global get-together 


News 

EVENTS 

of the metallurgy sectors in 

2011, has proven once again 

to be an efficient platform for 

making new contacts. Current 

trends were discussed 

at a very high level and the 

trade fairs also served as marketplaces 

for preparing and 

concluding business deals. 

Also meeting with special 

interest among trade visitors 

was the campaign for 

energy efficiency and saving 

resources “ecoMetals” participated 

in by 28 high-calibre 

international exhibitors. This 

means the four technology 

trade fairs also served as 

Euro PM2011exceeds expectations 

The Euro PM2011 international 

exhibition from 9 th to 

12 nd October 2011 will provide 

delegates and visitors 

with the chance to up-date 

their contacts, network with 

potential suppliers and see at 

first hand the new developments 

in the industry, all in 

one place. There will also be 

the opportunity to see pressing 

equipment displays, discuss 

new projects and sample 

a range of industry related 

magazines/journals. “The 

level of exhibiting companies 

at this year’s event is a good 

indicator that confidence is 

starting to come back into 

the PM industry supply sector”, 

said Andrew Almond, 

Euro PM Exhibition Manager. 

After hours, participants will 

have the opportunity to relax 

forums for discussing medium 

and long-term sustainability 

strategies and, hence, for the 

development of metallurgical 

technologies of the future. 

And the diverse programme 

of side events also gave trade 

visitors excellent value added. 

Each of the four trade fairs 

came with matching congresses, 

seminars, discussion 

forums or competitions meeting 

with avid interest. 

GIFA, METEC, THERMPRO- 

CESS and NEWCAST will 

again be presented jointly as 

technology trade fair quartet 

in summer 2015. 

and enjoy the rich history and 

wonderful sights of one of 

Europe’s more dynamic cities, 

Barcelona. In addition to 

the day-to-day business of 

PM there will be a full range 

of social program tours and 

receptions, including a Gala 

Dinner that will take place at 

the Casa Llotja de Mar in the 

heart of Barcelona. 

Advanced delegate bookings 

for this year’s event are 

now being taken, with the 

2 nd September as the final 

day for taking advantage of 

the discounts available. Further 

information on the Euro 

PM2011 Congress & Exhibition, 

including the Euro 

PM2011 technical program, 

please visit: 

www.epma.com/pm2011. 

10 % to 19,700, it is already 

emerging even now that the 

companies are extremely 

interested in E-world 2012: 

Since the end of April 2011, 

over 70 % of the exhibition 

area has already been rented 

out. This illustrates: The success 

and constant growth of 

the leading sectoral meeting 

place of the European energy 

and water industries are continuing 

even further. 

Due to the great demand, an 

additional fair hall had already 

been opened on the occasion 

of E-world 2011. Thus, 

41,000 m 2 in five fair halls 

was available to the exhibi- 

China announced as partner country 

of HANNOVER MESSE 2012 

The People’s Republic of 

China will be honored as 

the official partner country 

at HANNOVER MESSE 2012 

(the Hannover Fair) in Hannover, 

Germany. Germany’s 

Federal Minister of Economics 

and Technology, Dr. Philipp 

Rösler, and the Chinese Minister 

for Industry and Information 

Technology, Miao Wei, 

signed a cooperation agreement 

to this effect in Berlin 

on June 28 th . The parties 

to the agreement are convinced 

that China’s Partner 

Country showcase at HAN- 

NOVER MESSE 2012 offers 

rich opportunities for fostering 

and intensifying bilateral 

economic and trade relations 

between Germany and the 

People’s Republic. In realizing 

their joint project, Deutsche 

Messe AG and the China 

Council for the Promotion of 

International Trade (CCPIT) 

are receiving political support 

tors for the first time this 

year. The future subject of 

„smart energy“ will again be 

one of the main focal points 

at E-world 2012. Intelligent 

networks, meters or also networked 

house technology 

will be the centre of attention 

there. For further information, 

please visit: 

www.e-world-2012.com. 

on the part of the German 

Federal Ministry of Economics 

and Technology and the Chinese 

Ministry for Industry and 

Information Technology. The 

contract was signed in the 

context of German-Chinese 

government consultations 

held at the German Federal 

Chancellery. 

The Chairman of the Managing 

Board of Deutsche Messe 

AG, Dr. Wolfram v. Fritsch, 

issued the following statement: 

“We look forward very 

much to hosting and honoring 

China as the Partner Country 

at HANNOVER MESSE 2012. 

We are convinced that this 

partnership will give a strong 

boost to German-Chinese 

economic relations and create 

a major attraction for exhibitors 

and visitors from all over 

the globe. All the participants 

in HANNOVER MESSE will 

have an opportunity to step 

up their import and export 

E-world energy & water at Messe Essen in 2012 

On February 7 th to 9 th , 2012, 

the 12 th E-world energy & 

water will take place at Messe 

Essen. After the success of 

this year‘s fair where the 

number of exhibitors rose by 

eight percent to 544 and the 

number of visitors by around 

234 


News 

EVENTS 

activities with China and 

intensify their scientific and 

business contacts.” 

The People’s Republic of 

China numbers among the 

major exhibiting nations at 

HANNOVER MESSE. More 

than 500 Chinese exhibitors 

participated in the show 

in 2011. In the coming year 

China is expected to present 

various government-funded 

research projects in the area 

of energy efficiency ranging 

from power generation 

and smart grid systems to 

eco-friendly road vehicles. 

The People’s Republic has 

launched an extensive program 

aimed at restructuring 

its economy along more 

ecological lines. This will 

stimulate strong demand in 

sectors outside China’s classic 

exporting industries – for 

example, in transport infrastructure, 

power generation, 

mine safety, environmental 

protection and healthcare. 

Alongside its traditional 

industrial technology highlights, 

HANNOVER MESSE 

2012 will focus on green 

solutions. Next year will see 

the premiere of the new 

trade show “IndustrialGreen- 

Tec”. In short, HANNOVER 

MESSE 2012 will cover all 

the issues of key relevance to 

the Chinese market. For further 

information, please visit 

www.hannovermesse.de 

wire / tube ASIA 2011 gears up for a strong 

showing 

wire / tube Southeast ASIA 

2011, 13 rd to 15 th September 

in Bangkok (Thailand), 

is gearing up for a strong 

showing with preparations in 

full swing of the key industry 

networking, sourcing and 

knowledge sharing platform 

for the wire, cable, tube and 

pipe sectors. More than 300 

exhibitors from 30 countries 

are expected to share their 

expertise and latest innovations 

with industry professionals 

and business visitors from 

around the world. In addition 

national pavilions and groups 

from Austria, China, Germany, 

Italy, Singapore, the 

USA, United Kingdom, and 

Taiwan will contribute to the 

internationality and variety of 

both trade fairs. 

Visitors can expect to see 

products and services from 

across a range of sectors 

including wire, cable, tube 

and pipe manufacturers, 

machine manufacturers, 

inspection solution providers, 

raw material suppliers and 

many others. Working closely 

with exhibitors and visitors 

to ensure synergistic business 

matches and to enhance 

strategic capabilities, a business 

matching service will be 

Metal + Metallurgy China 2012 

Gifa / Metec / Thermprocess / 

Newcast ended. It turned out 

to be a real success by gathering 

people from every aspect 

of the industry together. 

A team, grouped by China 

Foundry Association, China 

Iron and Steel Association, 

Industrial Furnace Institution 

of CMES, and CIEC Exhibition 

Company Ltd, exhibited in 

GIFA / METEC for the onsite 

promotion of Metal + Metallurgy 

China, the second largest 

international exhibition 

in metallurgy and foundry 

industry. 

The team first met with the 

European supporters and 

clients. As the economy is 

gradually recovering, larger 

booths are expected by the 

national pavilions and individual 

companies which will 

surely make their appearance 

in Metal + Metallurgy China 

2012 as always. 

On the second day, the team 

provided. This complimentary 

service, which begins by registering 

online, will enable 

participants to view comprehensive 

exhibitor and visitor 

profiles or opt for automated 

business matches, and schedule 

appointments prior to the 

exhibition. Onsite during the 

exhibition, there will also be 

a business matching lounge 

and qualified staff on-hand 

to assist in facilitating business 

matching opportunities 

to meet the buying needs of 

visitors and to ensure effective 

use of time whilst at the 

event. 

With the impressive line-up 

of exhibitors and new innovations, 

and a comprehensive 

business matching service, 

the lead up to wire / tube 

Southeast ASIA 2011 is gaining 

momentum once again as 

Thailand’s leading exhibitions 

for the wire and tube industries. 

For more information, 

please visit www.wire-southeastasia.com 

or www.tubesoutheastasia.com. 

held a reception, named 

China Get Together Party, 

in Hall 10 and released the 

latest progress of Metal + 

Metallurgy China 2012. The 

leaders of the industry associations 

of different countries, 

exhibitors, supporters and clients 

of Metal + Metallurgy 

China attended this gathering. 

It also attracted a number 

of passersby. 

During the five days of the 

exhibition, quite a number of 

new faces who showed great 

interests to Metal + Metallurgy 

China and to Chinese 

market as well were known 

by the team. Their possible 

visiting or even exhibiting 

themselves in Metal + 

Metallurgy China 2012 will 

definitely ensure the event’s 

grandness and variety. Don’t 

miss this opportunity and 

start to plan your next trip to 

Metal + Metallurgy China. For 

further information, please 

visit www.mm-china.com. 

ICRF 2012 – Ingot production and transformation 

of the future 

With ICRF 2012 the Steel 

Institute VDEh is organizing 

its first conference for 

ingot casting and transforming. 

From June 3 rd until June 

7 th 2012 the specialists will 

meet in Aachen, Germany, 

for a dialogue on the state 

of the art of ingot casting 

and remelting, as well as the 

236 


needs arising through rolling 

and forging. More than 

400 experts from around the 

world are expected to attend 

this international event. 

Particularly in the production 

of special steels, and with a 

global share of 8 % in steel 

manufacturing, the ingot casting 

production plays an indispensable 

role. Among others, 

ingot casting products are 

required for power turbines 

responsible for power generation, 

and in the aviation 

and space industry. Further 

processing of the ingots and 

slabs involve rolling mills and 

forges. In the first ICRF 2012, 

a dialogue between steel 

manufacturers and specialists 

for metal forming as well as 

for users in machinery, aerospace, 

energy and research 

will be conducted. The aim 

is to provide a comprehensive 

overview of the available 

ingot casting, remelting, forging 

and rolling process and to 

identify technological trends 

and developments. 

The ICRF 2012 is offering 

experts of the various involved 

disciplines a broad international 

discussion platform for 

the first time. The program 

of presentations allows for a 

considerable amount of free 

time to establish new contacts 

with the experts and to 

intensify those already existing. 

In the accompanying 

exhibition various companies 

will present their solutions 

for ingot casting, rolling and 

forging technology and introduce 

new products and services. 

The latest information about 

visits and the conference program 

can be found at www. 

icrf2012.com. 

The international magazine 

for industrial furnaces, 

heat treatment plants and 

equipment 

The technical journal for the entire fi eld of industrial 

furnace and heat treatment engineering, thermal 

plants, systems and processes. The publication 

delivers comprehensive information, in full technical 

detail, on developments and solutions in thermal 

process engineering for industrial applications. 

Now 

also available 

as epaper 

Personal 

Leif-Arne Langøy and Walter Qvam are the new 

chairmen of DNV 

Leif-Arne Langøy has been 

elected as the new Chairman 

of the Board of Directors 

of DNV (Det Norske Veritas). 

Walter Qvam has been 

elected as the new Chairman 

of the DNV Council. In addition, 

Morten Ulstein has been 

elected Vice Chairman of the 

DNV Board. The elections 

took place at the Council 

meeting on Wednesday, 8 th 

June 2011. 

Leif-Arne Langøy has been a 

member and Vice Chairman 

of DNV’s Board since 2010. 

He has an MSc from the Norwegian 

School of Economics 

and Business Administration 

in Bergen. He has held 

a number of senior positions 

and directorships in the Aker 

system during the past few 

years and was the CEO of 

Aker ASA until 2009. He is 

also the Chairman of Sparebanken 

Møre, a director of 

Istad AS, and Vice Chairman 

of The Resource Group AS 

(TRG). 

Walter Qvam holds an MSc in 

Engineering from the Norwegian 

Institute of Technology 

(now the Norwegian University 

of Science and Technol- 

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News 

personal 

ogy). He was employed by 

DNV from 1980 to 1994 and 

has later been Deputy CEO of 

the Norwegian State Railways 

(NSB) and CEO and Chairman 

of the Board of Capgemini in 

Norway. He established the 

consulting company Bene 

Agere before taking over as 

CEO of Kongsberg Gruppen 

ASA in 2007. 

DNV’s CEO, Henrik O. Madsen, 

is very positive about the 

election of such high calibre 

individuals, willing to commit 

their time to DNV and its governance. 

“Leif-Arne Langøy is 

an expert in his field; he has 

a considerable international 

network and knows the shipyard 

industry well. He also has 

a lot of experience of mergers 

and acquisitions. Walter 

Qvam knows DNV very 

well from the inside. He has 

worked for DNV for 14 years 

and has also been stationed 

abroad for us. Together, 

these two will play a key role 

in further developing DNV,” 

says Henrik O. Madsen. 

Eclipse in 2007 with a Human 

Resources and Operations 

background, and is relocating 

to the Eclipse European 

facility in Gouda, The Netherlands. 

Rick Steder is promoted to 

the role of Director Americas 

Operations. Steder joined 

Eclipse in 2006 and formerly 

worked with Coopers & 

Lybrand and Thermo-Fisher. 

Since joining Eclipse Steder 

has held various roles including 

Corporate Controller and 

leader of Rockford manufacturing 

operations. 

Tenova I2S welcomes Mr. B.C. Basu as Technical 

Director of Indo-Asian Sales 

Eclipse Inc. announces Jeff Townsend, 

Jim Corbett and Rick Steder to the Executive 

Management 

Eclipse announces the appointment 

of Jeff Townsend as 

Vice President, Business Operations; 

Jim Corbett as Director 

of European Operations 

and Rick Steder as Director of 

Americas Operations. These 

promotions come as a result 

of growth and expansion of 

the company’s business activities. 

Jeff Townsend has a very 

diverse background of successes 

with Eclipse and has 

led various functional areas 

of the company including, 

sales, administration and 

operations. He joined Eclipse 

in 1987 and has directed 

numerous company-wide initiatives. 

The regional business 

unit Directors will report to 

Townsend. 

Jim Corbett, as the Director 

of European Operations, will 

have full responsibility for 

all of the Eclipse European 

operations. This will involve 

directing and coordinating 

activities to create and implement 

strategies for success 

in the region. Corbett joined 

Tenova I2S will use Mr. Basu 

to aggressively market our 

Cold Rolling Mill Technology 

including new 20hi, 6hi, 

4hi, 2hi and specialty mills in 

addition to mill modernizations, 

customized mill control 

systems and non-contact 

thickness gauges. Tenova 

I2S has a new focus on the 

India Region market and Mr. 

Basu's many years of experience 

complements the existing 

Tenova Multiform and 

Tenova Hypertherm business 

units in India. 

Gunther Voswinckel appointed as new Chief 

Executive Officer at Schoeller Werk GmbH 

It is the beginning of a new 

era at long-established 

Schoeller Werk GmbH Co. 

KG. Dr.-Ing. Dipl.-Wirt.-Ing. 

Gunther Voswinckel took 

over management of the 

Hellenthal-based company 

on April 1 st , 2011 and will 

take the reins of one of the 

world’s leading manufacturers 

of welded stainless steel 

tubes. Dr. Voswinckel succeeded 

Jörg Rumpf as chairman 

of the Management 

Board on Rumpf’s retirement 

in May 1 st , 2011. For the 

first time since the founding 

of Schoeller, a non-family 

member is at the head of the 

company. Voswinckel is supported 

by Frank Poschen and 

Jürgen Mensinger, who had 

been executives and have 

now also been called on the 

Board of Management. 

238 


News 

book review 

Book Review 

Modeling of Steelmaking Processes 

by Dipak Mazumdar, James W. Evans 

CRC Press, London, New York 

463 pages, Hardcover, 1 st Edition (2010) 

$ 144.95, ISBN: 978-1-4200-6243-4, www.crcpress.com 

furnaces and 

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Pocket Manual of Heat Processing 

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by Herbert Pfeifer 

Vulkan Verlag, Essen 

592 pages, 1 st Edition (2008) 

€ 59.90, ISBN: 978-3-8027-2944-7, www.vulkan-verlag.de 

Powder Metallurgy Hot Isostatic pressing 

brochure into French & German languages 

The European Powder Metallurgy 

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recently launched 

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Interest in heat engineering 

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deal with burners 

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Commonly Asked Questions in Thermodynamics 

by Marc J. Assael, Anthony R. H. Goodwin, 

Michael Stamatoudis, William A. Wakeham, Stefan Will 

CRC Press, London 

368 pages, Paperback, 1 st Edition (2011) 

£25.99, ISBN: 978-1-4200-8695-9, www.crcpress.com 

Commonly Asked Questions 

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240 


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BOOK REVIEW 

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Operation and Control in Power Systems 

EPMA launches updated Powder Metallurgy Case 

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A revised booklet containing a selection of “Powder Metallurgy 

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“Operation and Control in 

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HÄRTEREI-KOLLOQUIUM 2011 

WIESBADEN 

12. – 14. Oct. 2011 

Visit HEAT PROCESSING 

in Hall 9, booth 909 

KNOWLEDGE 

for the 

FUTURE


Reports 

High-efficiency quenching and 

tempering plants based on 

comprehensive process expertise 

Holger Kehler, Dominikus Schröder, Wolfram Schupe 

In the past, steel plate was more or less a mass-produced commodity, 

However, over the past few years, increasing calls for high-strength, 

wear-resistant special steels from downstream industrial sectors have 

meant that steel plate has more and more become a high-quality product. 

The result has been the development of a new market sector, which 

is likely to remain the fastest-growing sector in the steel plate industry 

in the future. New material grades and increasingly stringent strength, 

corrosion resistance and forming specifications are some of the requirements 

resulting from market trends towards leaner steel structures bringing 

greater benefits in use. In order to meet these requirements, it is 

necessary to deploy not only advanced rolling mill technology but also 

innovative heat treatment, allowing the specifications to be met in line 

with customers‘ requirements and at reasonable cost. 

Special steel plates are now normally 

available in thicknesses ranging from 

3 to 100 mm. They are used in bridges 

and shipbuilding as well as for pressure 

vessels, line pipes, cranes, commercial 

vehicles and construction and 

earthmoving machinery. Depending on 

the individual application, the plates 

are quenched and tempered to obtain 

specified properties such as strength, 

hardness, wear resistance and abrasion 

resistance. 

LOI Thermprocess, a company of the 

LOI Italimpianti Group, was able to 

offer quenching and tempering lines 

precisely tailored to customers‘ growing 

requirements for process security, 

quality and flexibility. Quenching and 

tempering lines for high-quality steel 

plate is only possible with furnaces and 

quench facilities designed on the basis 

of comprehensive in-depth process 

expertise in combination with an effective 

overall automation concept based 

on mathematical modelling (Fig. 1). For 

LOI Thermprocess, many years of experience 

in the construction of reheating 

and quenching and tempering plants 

for the automotive and machinery 

industries laid ideal foundations for the 

development of single- source solutions 

including plants and harmonized process 

models tailored to customers‘ individual 

applications (Fig. 2). 

What are the main features of 

a high-efficiency quenching 

and tempering line for steel 

plate? 

In this case, „high-efficiency“ means 

that the plant can implement the various 

processes required in a targeted way, 

cost-effectively and with high energy 

efficiency at the same time as offering 

the operator a high degree of flexibility 

in achieving individual properties. 

However, there is another key element 

in LOI‘s expertise for the production of 

quenching and tempering plants for 

high-grade and special steel plate. The 

furnace and the quench facility are both 

integral parts of a harmonized overall 

concept in which equal priority is given 

to automation and the use of process 

models. This is the only approach which 

ensures that the operator can be certain 

before charging the furnace and completing 

the treatment process that the 

charge material will have the specified 

properties, which may differ from plate 

to plate, when leaving the furnace line 

(Fig. 3). 

For implementation, LOI draws upon 

in-depth knowledge of the physical 

processes involved and treatment programmes 

developed on the basis of 

experience and stored in an in-house 

database where they are available to 

a dedicated team of highly qualified 

experts working only on technical questions 

connected with quenching and 

tempering. Specialists develop mathematical 

models, for example for the 

quenching and tempering of steel plate, 

which can achieve far more than a conventional 

furnace control system. 

The main characteristic of process models 

is the ability to precisely define the 

Fig. 1: Plate at quench entrance 


Reports 


Fig. 2: Heavy plate heat treatment line at Baosteel, China 

results of heat treatment through the 

preliminary setting and dynamic adjustment 

of parameters. For this purpose, it 

is essential to know the actual position, 

temperature and degree of heating of 

every plate in the furnace at all times; 

cooling parameters for the quench facility 

are defined on this basis. 

The process model mainly consists of: 

• a heating model defining the optimum 

temperatures in the various 

furnace sections; 

• speed settings ensuring that the heat 

treatment process is properly completed 

at the plant outlet; 

• a preliminary open-loop temperature 

control function based on the 

calculated energy requirements and 

intended to make closed-loop temperature 

control more effective; this 

approach allows the ideal temperature 

to be reached faster and more 

precisely, making the furnace considerably 

more energy-efficient; 

• fully automated material flow control 

using highly advanced HMI systems; 

• fast and precise water flow control in 

the quench facility; 

• dynamic parameter adaptation during 

the process to optimize quenching 

with a view to improving levelness 

and making mechanical properties 

more homogeneous; 

• plate temperature plot predictions for 

heating and quenching (Fig. 4). 

These plants are designed for flexible, 

reliable reactions to operators‘ requirements, 

which is especially important if 

plates with very different thicknesses are 

to be treated in succession. For example, 

if a 100 mm plate is followed by a plate 

with a thickness of only 5 mm at the 

furnace inlet, the control system will 

not allow the quenching and tempering 

process to start until furnace conditions 

are such that the time and temperature 

control parameters required by the process 

model can be reached. This ensures 

that the plate does not remain in the 

furnace for too short or too long a time. 

As an integral part of an overall control 

system, the model also takes into 

account delays caused by malfunctions 

downstream from the quenching and 

tempering line. In this case, the temperature 

is reduced to the value required 

to obtain the quality values specified in 

view of the expected duration of the 

problem. 

Apart from its online model, LOI has 

recently introduced a program to predict 

the properties of finished products in 

advance on the basis of the steel grade 

concerned. This means that the operator 

of a quenching and tempering plant 

can provide customers with advance 

information on the feasibility of achieving 

product properties required (such as 

hardness distributions, wear resistance, 

etc.) on the basis of calculated structure 

fractions (martensite, bainite and/or ferrite/pearlite). 

The offline process models are based 

solely on calculations which are compared 

with a database and not on 

empirical values intended to gradually 

approach the required result. The process 

security developed by this approach 

can reduce the time required for commissioning 

a new quenching and tempering 

line by several months. 

The thermal process of 

quenching and tempering for 

steel plate 

For rolled and moulded steel products, 

the thermal process of quenching and 

tempering normally consists of the following 

three stages: 

Fig. 3: 

Modern control 

centre 

• Heating the material to austenitizing 

temperature 

• “Quenching“ – i.e. very rapid cooling 

• “Tempering“ – i.e. reheating to tempering 

temperature followed by slow 

cooling 

244 



Reports 

These process stages are defined specifically 

for the material and application 

in hand and laid down in TTT (timetemperature-transformation) 

diagrams 

(Fig. 5). When producing individual 

parts, it is generally possible to take the 

time constraints for these processes into 

consideration without any problems. 

In contrast, the continuous processing 

normally required at the end of a plate 

production line poses considerable challenges 

for plant design and construction. 

These challenges already start with 

the dimensions which have become 

normal practice in plate production. The 

plates produced may weigh between 20 

and 40 t, with widths between 3 and 

5 m and thicknesses normally ranging 

from 10 to 150 mm (although plates 

may be as thin as 3 mm or as thick as 

250 mm in exceptional cases). Lengths 

range from 8 to 30 m. Modern quenching 

and tempering lines reach throughputs 

between 40 and 60 t/hour. The 

largest quenching and tempering plant 

for steel plate built by LOI Thermprocess 

to date, for ThyssenKrupp Stahl, reaches 

a capacity of 105 t/hour (Fig. 6). 

The quality of the end product is determined 

by temperature control during 

heating, quenching and tempering. The 

specified microstructure can only be 

reached for a specific material grate and 

dimensions if the times and temperatures 

laid down in the TTT diagram are 

followed within very tight tolerances. 

The process may be illustrated by taking 

the example of a plate with a thickness 

of 10 mm: 

• First, the plate must be heated to 

austenitizing temperature within 15 

min and held at this temperature for 

a short time. The temperature tolerance 

in this case is only ± 3 K. 

• The plate is then quenched; in this 

process, it must be cooled through 

the temperature range critical for 

hardening in less than 2 sec. 

• These two stages are followed by 

tempering for 45 min with temperature 

tolerances of ± 3 K (Fig. 7). 

Initially, the charge is heated to austenitizing 

temperature in a roller hearth 

furnace to completely dissolve the carbon, 

present in the steel in the form of 

carbides at room temperature. These 

furnaces may be heated either by open 

burners firing directly into the furnace 

itself, or indirectly by radiant tubes. In 

an indirectly heated furnace, a protective 

controlled atmosphere, usually con- 

Fig. 4: Heating up curves of the level-2-system 

allow independent control of the charge 

transfer speed in the various zones of 

the furnace. The rollers are equipped 

with reversing drives, allowing the rollers 

to be oscillated to prevent local overheating 

in the event that charge transfer 

is stopped as a result of a downstream 

problem. 

The heating systems used are in accordance 

with the most stringent energy 

efficiency and pollution control requiresisting 

of nitrogen, is used to present 

scale formation on the steel surface. 

Nitrogen consumption and heat losses 

are minimized by rapid charging and 

discharging of the plate (Fig. 8). 

Wider and wider plates call for new 

furnaces with increasingly large useful 

widths. As a result, special design 

measures need to be taken to prevent 

furnace rollers from sagging. The rollers 

are driven by individual motors to 

Fig. 5: TTT diagram 


Reports 


Fig. 6: Roller hearth furnace with continuous quench at Thyssen 

Krupp Steel Europe, Germany 

Fig. 8: Continuous roller furnaces at Baotou, China 

the quench section is extremely short, 

making it easy to integrate into an existing 

production line. 

Fig. 7: Heating, quenching and tempering of a plate 

ments. Over the past few years, LOI 

has made considerable efforts to use 

regenerative burners in addition to 

recuperative systems with a view to 

ensuring higher combustion efficiency, 

lower energy consumption and reduced 

carbon dioxide emissions in the future. 

Energy consumption is minimized and 

plate throughput and quality are simulated 

and controlled online by a mathematical 

model (Fig. 9). 

Stationary quench facilities 

Oscillating roller hearth furnaces may be 

combined with a stationary quench facility. 

This configuration allows throughputs 

of up to 10 t/hour: The length of 

A stationary quench facility can only 

quench one plate at any one time and 

is only slightly longer than the longest 

plate to be treated. The plate is transferred 

from the furnace to the quench 

facility at high speed and is firmly 

clamped in position. Water is then 

sprayed onto the plate from the top and 

bottom via nozzle tubes. The spray nozzles 

are controlled to form various spraying 

zones at the edges and centre of 

the plate. In combination with the rigid 

clamping of the plates, this approach 

ensures that the plates are equally level 

over their entire surface, a property that 

is especially important for thin plates. 

For this purpose, the spray pattern must 

be homogeneous and cover the entire 

The quench facility – the key 

component of a quenching and 

tempering line 

It is quenching that gives high-strength, 

wear-resistant steel plates their special 

properties. In this process, tight tolerances 

apply to heat distribution on the 

surface and in the interior of the plate. 

LOI Thermprocess supplies quenching 

and tempering lines for steel plate with 

two different types of quench facility; 

stationary and continuous. 

Fig. 9: 

ON/OFF burner 

control 

246 



Reports 

Fig. 10: Continuous quench 

plate surface. This calls for optimum 

nozzle configuration and a secure supply 

of high-pressure water. 

Continuous quench facility 

Continuous roller hearth furnaces with 

continuous quench facilities are used, 

if higher capacities are required. More 

than 20 plants of this type have commissioned 

since 2000. Each of the types 

of plant has its own advantages and it is 

always necessary to select the best plant 

for a specific application (Fig. 10). 

Quench facilities are installed at the furnace 

outlet. They are high-tech facilities 

which ensure martensitic hardening 

through very fast, controlled cooling. 

Water spraying is controlled by the 

higher-level process model. 

In the direction of charge transfer, a 

continuous quench facility is divided into 

a high-pressure and a low-pressure section. 

The charge transfer speed is determined 

chiefly by the plate thickness, but, 

as a general principle, it is higher than in 

the furnace upstream from the quench 

facility. The water pressure is approx. 8 

to 12 bar in the high-pressure section 

and about 4 bar in the low-pressure 

section. The critical quenching speed 

between about 800 and 500 °C (T 8/5 ) 

is reached by spraying high-speed water 

jets onto both sides of the plate. The 

jets are homogeneous over the width of 

the plate and can cool the plates with 

a cooling rating of more than 200 MW 

within 1 to 2 sec in a space of only 

20 cm. This first spray system is followed 

by a second high-pressure section with 

nozzles once again spraying water onto 

the top and bottom of the plate. The 

plates are then cooled to 100 °C in the 

low-pressure section. 

The high-pressure section is divided 

into several zones over the width of the 

quench facility depending on the plate 

width. The control and process model 

settings are selected so that the water 

flow rates to the various zones ensure 

uniform quenching over the width of 

the plate. The result is a plate material 

with highly homogeneous structure 

properties. 

In order to ensure that steel plates are 

equally level over their entire surface, 

the top quench frame is set to the plate 

thickness before a plate is transferred to 

the quench. This ensures that the spacing 

between the spray nozzle and the 

charge material is always equal at the 

top and the bottom of the plate. As 

the plate is discharged from the quench 

facility, an air curtain removes any residual 

water from the top of the plate. 

Conclusion 

The key advantage of continuous 

quench facilities, apart from higher 

throughput, is higher cooling rates as 

a result of higher specific water flow 

rates. The mechanical properties specified 

can therefore be reached with far 

lower alloying additions, resulting in 

significantly improved processing properties. 

The special quenching technology developed 

by LOI ensures outstanding levelness, 

a critical requirement especially 

for thin plate. Using dynamic parameter 

adaptation during treatment and model- 

based cooling processes, quenching 

and tempering plants can reach levelness 

tolerances up to 75 % below those 

specified in the ASTM standard. 

In an LOI quenching and tempering 

line for steel plate, the visible components 

(furnace and quench facility) are 

in accordance with the state of the art 

of furnace and quench system engineering. 

Together with the process models 

they form a closely meshed system 

which operates in a highly harmonious 

way. 

K 

Holger Kehler 

LOI THERMPPOCESS GmbH 

Essen (Germany) 

Tel.: +49 (0)201 1891-848 

holger.kehler@ 

loi-italimpianti.de 

Dr. Dominikus Schröder 



Tel.: +49 (0)201 1891-865 

dominik.schroeder@ 


Dr. Wolfram Schupe 



Tel.: +49 (0)201 1891-241 

wolfram.schupe@ 



KNOWLEDGE 

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FUTURE 

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Reports 

Advantages for nitrocarburizing 

processes with post oxidation in 

continous furnaces 

Olaf Irretier, David Salerno 

Oxycad NT ® is a heat treatment process newly developed by Safed Suisse 

and is based on the thermo-chemical diffusion processes – nitrocarburizing 

with postoxidation – and in special cases on a nal organic impregnation 

to increase corrosion resistance. 

The following technical article shows, that Oxycad NT ® combines the 

positive properties procedure signs of nitrocarburizing, i.e. increase of 

wear resistance by high surface hardness and reduced distortion. In addition 

the surface becomes dull black and the parts are mostly ready for 

installation. 

achived with nitrocarburizing. According 

to materials composition a nitriding 

depth up to a few tenths millimetre is 

possible (Fig. 2). 

Below compound layer the diffusion 

zone is suitable for supporting effects. 

Nitrides and carbides lead to hardness 

increase. The depth of the compound 

layer correlates to the thickness of the 

Due to typical nitrocarburizing processes 

Oxycad NT ® – used nitriding 

and carburizing suitable gases, at temperatures 

between 530 to 750 °C – to 

create a compound and a underneath 

lying diffusion layer (Fig. 1). 

Fundamentals of 

nitrocarburizing 

Nitrocarburizing is a thermo-chemical 

heat treatment process which leads to 

an increased concentration of nitrogen 

and carbon in parts surface and a creating 

of a nitride enriched compound and 

diffusion layer. 

In contrast to nitriding the main target 

of nitrocarburizing is to create a 5 to 

25 mm “white compound layer“ with 

optimized wear and corrosion resistance. 

In addition the corrosion resistance of a 

number of alloys can be raised significantly 

by final postoxidizing. 

In general nitrocarburizing – whether in 

gas, salt or plasma atmosphere – leads 

also to a reduction of frictional coefficients, 

by high abrasion resistance. 

Suitable nitrocarburizing layers distinguish 

thermal stability to nearly 500 °C 

and an improvement of strength characteristics. 

Due to the low temperatures 

compared to case hardening and the 

avoidance of martensitic hardening crystal 

lattice changes less residual stress are 

Fig. 1: Oxycad NT ® process 

Fig. 2: 

Phase diagram Fe – 

N in dependence of 

carbon activity 

(due to Kunze) 


Reports 


by postoxidation (Fe 3 O 4 ) which has an 

improved corrosion resistance result 

(Fig. 3). 

Continuous furnace technology 

The Oxycad NT ® is specially developed 

for the continuous heat treatment processes 

in conveyor belt furnaces of bulk 

materials. 

Fig. 4: Conveyor belt furnace for Oxycad NT ® nitrocarburizing (Safed) 

diffusion layer. Basically, the more alloy 

elements are used for the nitriding, the 

higher the surface hardness, but the 

Fig. 3: 

Oxide creation in 

dependence of 

temperature and 

the oxygen partial 

pressure 

(due to Weissohn) 

more slightly the thickness of the nitrocarburizing 

layer. An iron oxide layer is 

generated on the surface in addition 

Safed – conveyor belt furnaces are 

equipped with a suitable measuring 

and control technology are suited for 

the optimum use and application – also 

due to the demands of AMS 2750 D 

and CQI9 (Fig. 4). These furnaces offer 

basically a high precision, reliability for 

reproduction and fulfils therefore the 

high demands of nitrocarburizing. 

The special issues of this furnace technology 

are: 

• Automatic, continuous filling of the 

conveyor belt furnace 

• Fast heating up and high thermal 

transfer by circulation 

• Steady control of the atmosphere 

composition. 

The necessary gases are: 

• air, 

• ammonia (NH 3 ), 

• methanol (CH 3 OH), 

• propane (C 3 H 8 ) 

• water H 2 O. 

Quenching takes place in oil. The final 

covering and closing of the pores is carried 

out with organic corrosion prevention 

(Fig. 5). 

Nowadays the processes in the industrial 

furnaces allow as a rule generally 

a steady nitriding or nitrocarburizing 

of the essential material dimensions. 

Besides, the process observation and 

process regulation occurs through gas 

analyser, oxygen probe or nitriding 

probe. 

Fig. 5: Schematic drawing of conveyor belt furnace for nitrocarburizing due to Oxycad NT ® (Safed) 

250 



Reports 

Fig. 6: Blade for gras shears, 1.2357, 

50CrMoV13-14, nitrocarburizing (OXY- 

CAD ® ), postoxidation, final organic coating 

Fig. 7: Drive pinion for camshaft, 1.7131, 16MnCr5, nitrocarburizing 

(OXYCAD ® ) 

The process regulation by nitriding coefficient 

Kn of Safed-conveyor belt type 

furnaces under flow arrangements and 

the application of a H 2 probe which is 

used to “in process supervision in-situ” 

and process documentation are „a state 

of the art” technology“ and have been 

proved in a huge number of applications 

by which process security and ability 

for reproduction of the heat treatment 

results were improved clearly. 

In addition the gas consumption and 

therefore the operating expenses significantly 

which can amount by using 

Table 1: Layer composition and surface hardness of the test parts 

of ammonia absolutely up to 30 %. 

This could be reduced by the regulated 

process guidance. Moreover, the regulation 

of the nitriding coefficient Kn is the 

necessary base realise the exact requirement 

and chemical compositions of the 

nitriding layers. 

Moreover, the process times can be 

minimised by a reproduceable creation 

of the nitriding layer. The continuous 

measurement of the furnace atmosphere 

(e.g. H 2 ) and the fed fresh gas, 

as well as the atmospheres and nitriding 

coefficient as well as the gap gas 

or hydrogen for the adaptation of the 

nitriding coefficient by e.g. automatic 

gas flow regulators is necessary for this. 

Applications 

With Oxycad NT ® -processes nearly all 

kind of steels, i.e. unalloyed as well as 

highly alloyed steels with more than 

13 % of chromium which have a tendency 

of passivation can be heat treated. 

Branches in which this process is used 

are for example automotive and aircraft 

industry, connection technology, electronics/electrical 

engineering, mechanical 

engineering, medicine industry and 

textile industry, military technology and 

tool industry. 

Waves and bolts count, e.g., in general 

to the special applications for 

internal combustion engines and compressors, 

precision parts for optical 

devices, punching and forging parts to 

ball plug seaweeds or ball bolts, piston 

Fig. 8: Car seat components, 1.0301, C10, 

nitrocarburizing (OXYCAD ® ) 


Reports 


Fig. 9: Metallographic microsection of Oxycad 

NT ® layer of a gearwheel 

rods, hinges, windshield wipers, shock 

absorbers, bolts and springs. 

In Fig. 6, 7 and 8 some common examples 

are shown which were treated in 

Oxycad NT ® processes. 

Test results 

The test results introduced in the present 

contribution show that the expected 

high wear and corrosion resistance can 

be reached by Oxycad NT ® . This thermal 

process is therefore in addition an interesting 

alternative for chromium-plating, 

bondering or also nickelplating. 

Confessed as adequately, the effect of 

the hardness increase in nitrocarburizing 

Fig. 11: Metallographic microsection 

(Oxycad NT ® ) 

is not based by the martensitic hardening, 

but by originating the „hard and 

wear-resistant“ iron- and special nitride 

as well as iron- and special carbide layers 

of the component. 

The highest hardness occurs to aluminium 

and chromium nitride as well as 

tungsten and chromium carbide. Hence, 

these elements has to be alloyed to 

become the hardness increase for nitrocarburizing. 

Nitrocarburizing does not lead to a crystal 

structure change, therefore dimension 

changes and distortion are substantially 

lower in comparison to case 

hardening. 

Table 1 shows how the Oxycad NT ® 

processes achieved test results. By variation 

of the process parametres the properties 

of the nitrocarburizing layers optimum 

for the uses were achieved: Oxide 

layer thickness (Fe 3 O 4 ) of about 1 to 

2 mm and a connecting nitrocarburizing 

layer thickness of approx. 5 to 25 mm 

with controlled porosity corresponding 

nitriding hardness depth (NHT) with 0.1 

to 0.4 mm. The surface hardness in the 

series of experiments were between 500 

in 1150 HV 0.5 (Fig. 9, 10 and 11). 

The process temperatures opposed 

in the investigations were between 

520 and 580 °C. There by it could be 

reached that according to material a 

surface hardness from up to 1250 HV 

appears. With wide increasing temperature 

the hardness of the nitriding layer 

decrease again (Fig. 12). 

Conclusion 

The test results have shown that Oxycad 

NT ® on one side combines the very 

Fig. 10: Metallographic microsection of an 

Oxycad NT ® layer 

positive properties of nitrocarburizing, 

i.e. increase of the surface hardness and 

high corrosion resistance. 

Especially the increases in the corrosion 

resistance according to salt spray test 

this process is suited for a huge number 

of demands and shows an interesting 

alternative to combined procedure used 

in the past for heat treatment and galvanic 

technology. 

The article shows that Oxycad NT ® process 

has the following advantages: 

• Optimisation of mechanical qualities 

and properties 

• Optimisation of corrosion resistance: 

>300 h in the salt spray test are possible 

• Substitute for other galvanic processes 

• Less distortion 

• Energy efficient and less of the operating 

expenses 

• Black colouring of the surface K 

Dr.-Ing. Olaf Irretier 

Industrieberatung für 

Wärmebehandlungs technik 

IBW Dr. Irretier 

Kleve (Germany) 

Tel.: +49 (0) 2821 / 7153 948 

olaf.irretier@t-online.de 

Dipl.-Ing. David Salerno 

Safed Suisse 

Delémont (Switzerland) 

Fig. 12: GDOS – element depth profile (Oxycad NT ® ) 

Tel.: +41 (0) 32 / 421 4469 

salerno.d@safed.ch 

252 



Reports 

Relations between global 

recirculation ratio and area ratio 

in combustors fired with jets 


This paper deals with the conception of burners aiming at a desired value 

of recirculation ratio, K V . This is particularly important to flameless oxidation, 

a combustion technique relevant for heat processing applications. 

First, from physical reasoning, it is established that K V does not depend on 

injection velocity and is governed by the chamber-to-nozzles area ratio, α. 

Next, two fundamental configurations are studied with a numerical tool, 

to obtain curves that allow the estimation of the area ratio necessary to 

obtain a determined K V . In the particular case of the design of flameless 

oxidation jet-fired burners, values of α>40 should be sought. The results, 

presented in non-dimensional form, can be exploited in the design of 

systems based on jet entrainment to achieve dilution of the incoming 

fluid, whether in the combustion field or others. 

does not vary with injection velocity but 

depends on the ratio of cross-sectional 

area of the combustor to area of injection. 

Therefore, systems for operation 

in the flameless oxidation regime are 

probably being designed based on the 

dimensions found in conventional systems 

for the same power level, instead 

of adapting them for the new situation. 

Clearly, design rules are needed to aid 

in the conception of burners aiming at 

a desired value of K V . The present paper 

is intended to fill this gap. 

When jets are issued into a confined 

space, recirculation zones are 

established. A recirculation zone is a 

subdomain of a flow field where, on 

average, half of the mass flow has a 

particular velocity component opposite 

to the other half, which in turn is in 

the dominant flow direction. The level 

of recirculation can be quantified by an 

integral parameter, K V , defined as the 

mass ratio of recirculated fluid to incoming 

fluid. It is a measure of the attained 

dilution of the jet fluid with surrounding 

fluid. 

In combustion systems, recirculated 

fluid consists of combustion gases and 

incoming fluid corresponds to reactants. 

Some combustion techniques rely on 

an appropriate recirculating flow pattern 

for flame stabilization and/or for 

reduced pollutants formation. 

Flameless oxidation 

Flameless oxidation is a combustion 

technique that results in: uniform temperature 

within the furnace, ultra-low 

NO x emissions and less combustion 

noise due to the absence of a thin flame 

front. Therefore it has been receiving 

great attention for application in heat 

treatment processes where all those 

characteristics are important. 

Originally, K V has been proposed as 

one of the most important parameters 

for establishing the flameless oxidation 

regime [1], another being the furnace 

temperature. The minimum K V generally 

accepted as required for this combustion 

technique is 3. The change in 

combustion regime, from conventional 

to flameless, shall be smooth as K V 

increases from, say, 1 to above 3. 

Motivation for the present study 

and contribution 

Even though it can be argued that 

values of K V below 3 do not necessarily 

exclude the operation in flameless 

regime [2], the benefits of operation at 

higher K V are more extensive. Nevertheless, 

so-called flameless oxidation burners 

continue to be designed without 

achieving high values of K V , with values 

around unity being the most common. 

It seems that designers implicitly consider 

K V to be an operational parameter, 

expecting that its value can be 

easily adjusted later, during operation, 

and hence, not worth giving much 

attention during the design stage. A 

common misconception is to consider 

that K V can be adjusted with the injection 

velocity. As is discussed later, K V 

The study here reported focus on cylindrical 

chambers in which fluid is fed from 

one end as a jet or jets, colinear to the 

chamber, issuing from circular nozzles 

(see Fig. 1). The results and conclusions 

herein can be extended to other topologically 

equivalent geometries, such as 

prismatic chambers, found in the combustion 

field or others. 

K V is more readily estimated numerically 

than experimentally and hence, a 

numerical approach has been used for 

this study. The curves of K V vs. area ratio 

obtained can be an important aid in systems 

design. 

To relate combustion system geometry 

and K V , it is important to understand 

the fundamentals physics that establishes 

the flow pattern within the chamber. 

This is done in the next section. 

Problem physics 

Jet entrainment and recirculation 

pattern 

When a jet issues into a quiescent 

medium, momentum is transferred 

across the shear layer and the surrounding 

fluid acquires velocity in the direction 

of the jet. The surrounding fluid 

progressively becomes part of the jet. 

This process is named jet entrainment. 

As the jet develops, velocity gradients 


Reports 


a) 

b) 

Fig.1: Plan view of the two configurations 

considered: a) coaxial nozzle; b) identical 

nozzles arranged in a ring 

across the shear layer are reduced, the 

jet widens and its centreline velocity 

decreases. 

In practical systems, jets are confined 

and there is a limited volume of fluid 

to be entrained. During an initial phase 

of the jets progression in the chamber, 

they entrain available surrounding fluid, 

and the mass flow rate associated to 

the jets steadily increases. However, the 

flow through the chamber must satisfy 

mass balance. In steady conditions, that 

means that the mass flow rate at the 

chamber’s outlet must equal the mass 

flow rate going through the nozzles at 

the base of the chamber. This is only 

possible if the mass that was entrained 

into the jet is given back to the chamber 

afterwards. Otherwise, the fundamental 

law of mass balance would be violated 

and more fluid would exit the chamber 

than the amount that entered. 

Mass balance can also be applied to a 

cross-section slice of the chamber to 

conclude that the fluid that is returned 

to the chamber has to travel upstream 

in order to be re-entrained by the jets. 

Hence a flow pattern is established that 

corresponds to the definition of a recirculation 

zone (RZ) given in the Introduction. 

Depending on the location of the 

nozzles, one or more RZ’s can be 

established. For the single coaxial jet 

configuration (Fig. 1a), a large toroidal 

RZ develops between the jet and 

the chamber wall. For an annular jet 

configuration an additional toroidal RZ 

is formed at the centre of the chamber. 

For the second configuration being considered 

here (Fig. 1b), the resulting flow 

pattern is more complex: central and 

peripheral RZ’s are established, that are 

interconnected in the spaces between 

jets and are modulated by the presence 

of the discrete jets. 

It should be noted that when all the 

fluid entrained has been given back to 

the chamber, the jets have reached the 

chamber walls and/or the chamber axis, 

and a plug type of flow is found thereafter. 

Then, the RZ’s will close at either 

a stagnation line established at the wall, 

or at a saddle point on the chamber 

axis. The length of a RZ is defined by 

the location of such particular features. 

Recirculation ratio 

By continuity, under steady conditions, 

the mass flow moving upstream equals 

the mass flow entrained by the jets, at 

any given cross-section: 

 

(1) 

As discussed above, the mass flow rate 

associated to the jets increases while 

there is fluid available in the chamber 

for entrainment and, after reaching 

a maximum (corresponding to depletion 

of surrounding fluid), it decreases 

back to the the original mass flow rate 

injected through the nozzles, to satisfy 

mass balance applied to the chamber 

as a whole. Hence, the ratio ṁ up. (x)/ṁ in 

(corresponding to a local K V ) varies 

along the chamber, going through a 

maximum. Usually, one is interested in 

the maximum value of the ratio, here 

labelled global K V , because it is a measure 

of the maximum attained dilution 

of the jet fluid: 

 

(2) 

Values of 1 and 3 for K V signify that 

the fluid in the jet (reactants, in a combustion 

system) is diluted to 50 % and 

to 25 %, on a mass basis, respectively. 

(The above expression applies only to 

the entrainment phase; in the fluid 

rejection phase the dilution level of the 

jet-fluid remains nearly constant.) 

Effect of injection velocity and 

area ratio 

A free jet entrains surrounding fluid at 

a rate directly proportional to its mass 

flow rate at the origin (see e.g. [3]), at 

least for constant density conditions. 

Neglecting the small off-set caused by 

the potential cone, immediately downstream 

of the nozzle, it can be written: 

ṁ entr. = C.ṁ in , where C is a constant. 

Therefore, it can be concluded that K V 

does not depend on the injection velocity: 

 

(3) 

Increasing the injection velocity simply 

causes the velocities in the RZ’s to 

increase proportionally. The RZ’s rotate 

faster while maintaining the value of 

recirculation ratio. 

Clearly, larger values of K V are attained 

when there is more fluid available for 

entrainment by the jets. This implies 

wider chambers, that must also be proportionally 

longer to allow for the RZ’s 

to close within. From what has been 

discussed, the value of global K V that is 

obtained in a particular constant density 

system shall be related to the ratio of 

the volumes of the RZ’s, V RZ , and the 

volume of the jet: 

 

(4) 

where V C is the total volume of the 

chamber and V J the volume of the jets. 

V J is the integration, along the streamwise 

direction, of the jets’ cross-sectional 

areas that are traversed by a mass 

flow rate ṁ in: 

with 

 

 

(5) 

(6) 

The difficulty in calculating V J renders 

the ratio of volumes in (4) impractical 

for use at early design stages. However, 

a simpler and more useful relation 

can be inferred from (4), and that only 

involves well defined areas: 

 

(7) 

254 



Reports 

Here A N stands for the combined areas 

of the nozzles mouths through which 

fluid is injected into the chamber of 

cross-sectional area A C . Although this 

ratio does not produce the same quantitative 

values as (4), it exhibits the 

same trend, and hence is most useful at 

design stage. 

It follows that K V is related to α, and 

the remainder of this article is concerned 

with obtaining the curves 

describing such dependence for the 

two configurations in Fig. 1. In the simplest 

case (single coaxial jet) α depends 

just on the chamber to nozzle diameter 

ratio. The multiple jets configuration 

introduces a second parameter for varying 

α: the number of nozzles, N. 

Numerical study 

Cases set-up 

The non-reacting, steady flow simulations 

have been performed with the CFD 

code FLUENT-ANSYS 13 [4]. Fluid is air, 

treated as incompressible. Turbulence is 

described with the RNG variant of the 

k-ε model. A previous study [5] showed 

that this two-equation model offers a 

reasonable balance between computational 

efficiency and accuracy. The standard 

second order pressure scheme is 

used for the pressure term of the RANS 

equations and the convective term is 

discretized using the QUICK scheme. 

The SIMPLE algorithm has been used for 

the pressure-velocity coupling. 

For the study of the single coaxial jet 

configurations, the chamber diameter 

was varied while keeping the inlet 

diameter constant. Injection velocity is 

70 ms -1 , resulting in a Reynolds number 

at the inlet of 2.8×10 5 . Two-dimensional 

unstructured meshes were generated, 

with 1.2×10 4 to 3.6×10 4 cells. 

The configurations of crowns of jets 

were studied taking the particular case 

of eight nozzles placed at a radius 71 % 

of the chamber radius. The integration 

domains consist of 45° cylindrical 

sectors, with the symmetry condition 

specified at the meridian planes. Additionally, 

a 4 nozzle, 90° sector has also 

been studied. The structured meshes 

have between 0.86×10 5 and 2.77×10 5 

hexahedrons, including refinements 

obtained with the hanging-node adaption 

technique. The injection velocity is 

equal to the coaxial jet cases, resulting 

in a Reynolds number (based on the 

inlet diameter) of 1.0×10 5 . The outflow 

condition is specified at the exit of the 

chamber, of length L/D=6. 

Results and discussion 

The results of K V vs. α, as defined by 

equations (3) and (7) are presented in 

Fig. 2. For both configurations studied 

the results follow a similar trend, with 

the multiple jet configuration yielding a 

certain K V at a slighly lower α than the 

coaxial jet configuration, in the range 

studied (α up to 50). This seems to be 

a consequence of the approximation 

used in going from expression (4) to (7). 

The degree of this approximation shall 

be slightly different between the two 

configurations. Nevertheless, α appears 

to be the parameter that influences the 

most the value of K V . The recirculation 

ratio does not depend on injection 

velocity, with points obtained for different 

values of this parameter appearing 

almost superimposed in the graph, and 

have been omitted for clearness. 

At α=15.5, decreasing the number of 

nozzles from 8 to 4 results in a decrease 

of just 4 % in K V . The deviation should 

have been even smaller if the relation of 

distances from a jet to its neighbour and 

to the wall would have been kept nearly 

the same. 

Analytical expressions of the curves 

fitting the numerical data are given. 

These curves allow estimation of the 

chamber-to-nozzle(s) area ratio necessary 

to obtain a determined K V . In the 

particular case of the design of flameless 

oxidation jet-fired burners, values of 

α>40 should be sought. 

Conclusion 

A numerical study was undertaken to 

quantify the relation between recirculation 

ratio, K V , and chamber-to-nozzle(s) 

area ratio, α, for two arrangements of 

jets colinear with cylindrical chambers: 

single coaxial jet and multiple jets in a 

ring arrangement. Flow is treated as 

constant density. The results follow a 

similar trend in both cases. They confirm 

the trend foreseen from theoretical reasoning, 

in this article, that K V is directly 

governed by the area ratio, α. 

The area ratio can be varied with the 

chamber-to-nozzle diameter ratio. In 

the case of multiple jets, the number of 

nozzles is available as a second parameter 

for varying α. The curves obtained 

are in non-dimensional form and can be 

exploited as a first approximation in the 

Fig. 2: Dependence of recirculation ratio 

with chamber-to-nozzle area ratio 

design of other configurations based on 

jet entrainment to achieve dilution of 

the incoming fluid. They can be used to 

design burners for a certain value of K V . 

In the particular case of flameless oxidation 

jet-fired burners, values of α>40 

should be sought. 

Even though the study has been motivated 

by the application of flameless 

oxidation to cylindrical combustors, the 

results and conclusions herein can be 

extended to other topologically equivalent 

geometries, found in the combustion 

field or others. 

Literature 

[1] Wünning, J.A., Wünning, J.G.: Progress 

in Energy and Combustion Science 23 

(1997), pp. 81-94 

[2] Vaz, D.C.: Towards the application of 

flameless combustion to micro gas turbines. 

PhD. Thesis. Lisbon: Universidade 

Nova de Lisboa, 2007 

[3] El-Mahallawy, F.M., Elasfouri, A.S., Rafat, 

N.M. and Youssef, M.M.: Scientific Engineering 

Bulletin, Cairo University (1983), 

p. 163 

[4] Fluent 13.0 User’s Guide. ANSYS, 2010 

[5] Vaz, D.C., Didier, E. and Borges, A.R.J.: 

Estudo da aerodinâmica interna de um 

sistema de combustão com múltiplos 

jactos usando modelos de turbulência de 

duas equações, in proceedings of the 1st 

CNMNMFT, Almada, Portugal, 2006 

Dr.-MSc.-Eng. 


Department of Mechanical 

and Industrial Engineering 

Universidade Nova de Lisboa 

Caparica (Portugal) 

Tel.: +351 21-2948567 

dv@fct.unl.pt 


Reports 


Eco-design study of industrial and 

laboratory furnaces and ovens 

Paul Goodman, Chris Robertson 

The European Commission is carrying out an eco-design study into industrial 

and laboratory furnaces and ovens. Eco-design studies are carried out 

as required by the Eco-design of Energy Related Products Direct with more 

than 40 studies started or completed and 13 EU Regulations imposed on 

manufacturers as a result. All Eco-design studies follow the same task 

structure that is designed to obtain the data required by the Commission 

to determine what action to take. The current study has established 

that energy consumption in the use phase has the largest environmental 

impact and that this sector consumes about 1.400 TWh of energy per 

year although there does appear to be potential for energy savings. 

The Ecodesign of Energy related Products 

Directive (2009/125/EC, which 

replaced the “EuP” directive 2005/32/ 

EC) aims to improve the environmental 

performance of products sold in EU that 

have the largest impact. In most cases 

this is by reduction of energy consumption 

and so far over forty studies have 

been started or completed and thirteen 

EU regulations have been adopted. A 

study carried out for the European Commission 

(EC) showed that industrial and 

laboratory furnaces and ovens was a 

very large consumer of energy and that 

significant improvement is possible. The 

EC awarded a contract to ERA Technology 

Ltd (previously Cobham Technical 

Services), working with Bio Intelligence 

Service, to carry out a preparatory study 

of all types of industrial and laboratory 

furnaces and ovens. The purpose of 

the study is to provide the Commission 

with sufficient data to enable it to make 

policy proposals which may include regulation. 

As such it is crucial that industry 

and other stakeholders are actively 

involved to ensure that the evidence 

reflects reality such that sensible policy 

proposals can be made. 

The EU has committed to reducing 

carbon dioxide emissions by 20 % by 

2020 and by 80 % by 2050. This will be 

very challenging and so not only will all 

industry sectors have to play a role but 

large reductions in the use of fossil fuels 

may be the only way to achieve this target: 

small changes will not be enough! 

Industrial and laboratory 

furnaces and ovens 

Research carried out for the EC found 

that industrial and laboratory furnaces 

and ovens are the fourth largest consumer 

of energy in the EU and it is clear 

that industrial furnaces do consume very 

large quantities of energy. This study is 

considering all types of ovens and furnaces 

ranging from small laboratory 

ovens to steel blast furnaces. 

Previous eco-design studies have 

reviewed relatively narrow ranges of 

standard products such as televisions, 

computers, refrigerators and electric 

motors but furnaces and ovens are far 

more varied with many custom designed 

non-standard furnaces being installed in 

the EU. The huge variety of designs is 

inevitably making this study rather complex. 

Eco-design preparatory 

study tasks 

The European Commission uses a standard 

procedure for all preparatory studies 

although this was originally designed 

for consumer products and so has not 

been straightforward to follow for furnaces 

and ovens. The procedure comprises 

seven tasks: 

Task 1: Definition and classification: 

Definition is important so that the scope 

of any future legislation is clear. The 

main defining characteristic of furnaces 

and ovens are that they have enclosed 

chambers and the interior are heated. 

Classification of types is also important 

as it is common with these studies that 

different obligations are applied to each 

classification. For example, gas and electrically 

heated equipment may need to 

be considered differently. Standards 

and legislation are also reviewed as part 

of task 1 as these may provide useful 

definitions and classifications as well as 

methods for measurement of energy 

consumption. Legislation is important 

as future eco-design requirements must 

not contradict existing legal obligations. 

As part of task 1, the Japan Energy Act 

was identified as an option for regulation 

of energy consumption by industrial 

furnaces and ovens. This imposes limits 

on the main performance parameters of 

large fossil fuel furnaces. 

Task 2: Market information including 

sales, prices and running costs is being 

collected and used for subsequent 

tasks. This is essential data for the study 

because it is necessary to determine the 

current environmental impact of this 

sector and the size of the improvement 

possible. The European Commission 

will impose eco-design requirements if 

significant improvement is achievable 

providing that this would not harm EU 

industry. Data from this task is important 

to determine the likely impact of 

eco-design options which are considered 

in later tasks. 

Task 3: User behaviour is reviewed. It is 

important to understand how furnaces 

and ovens are actually used. This helps 

to determine, for example EU energy 

consumption and provides information 

on any constraints that exist. 

Task 4: Current technology used for 

new and refurbished furnaces and ovens 

is reviewed. This is used to select representative 

furnaces and ovens for calculation 

of their environmental impacts. The 

impacts of a laboratory oven, a selection 

of medium-size furnaces and ovens and 

256 



Reports 

Fig. 1: Homogeneous heating of forging ingots to their working temperature of 1280° C. They are then used for forging of shafts, crankshafts, 

plates and many other items for power generating plants and drive systems of the most diverse types (source: Andritz MAERZ GmbH) 

a large furnace and one large oven have 

been calculated and unsurprisingly, the 

largest impacts are from energy consumption 

in the use phase. This task also 

estimates total EU energy consumption 

which is about 1.400 TWh/year which is 

a very significant percentage of total EU 

energy consumption (about 6 %), especially 

as most of this is from fossil fuels. 

Another conclusion from these calculations 

is that energy costs during the 

lifetime of the furnace or oven are far 

greater than the original purchase price. 

Task 5: Reviews the best available technology 

that is available in the EU. With 

the results from task 4, this task determines 

the potential for reducing energy 

consumption in the EU. The potential 

energy consumption from replacement 

of existing older furnaces and ovens with 

new is very large, possibly 150 TWh/year 

or more. However, there is also potential 

for further energy reductions by using 

technology that is available but frequently 

not used and this also appears 

to be very significant. Achieving this is 

however not straightforward due to a 

variety of complex and sometimes competing 

issues. New and refurbished fur- 

naces and ovens could be constructed 

having lower energy consumption than 

are actually installed in the EU although 

at a higher cost. The size of this cost is 

important but in many cases, the payback 

time to achieve significant energy 

savings is relatively short, often less than 

two years. However customers of furnace 

manufacturers are often unwilling 

to make or constrained from making 

this investment for a variety of reasons 

that are being investigated as part of 

this study. 

Task 6: The potential for eco-design 

improvements will be determined by 

comparison of new furnaces and ovens 

being sold in the EU using the best 

available technologies (irrespective of 

cost) and also consider possible future 

technologies. Eco-design studies determine 

best available technology (BAT) 

irrespective of cost which is different to 

the definition of BAT used by the IPPC 

(now IED) directive. Eco-design options 

will be identified that could be used by 

the European Commission to formulate 

legislation. This needs to determine the 

size of the potential energy saving and 

the cost. 

Task 7: The policy and impact analysis 

determines the overall impact on the 

EU from the design options identified in 

task 6. Policy options will include legislation 

that regulates the design of new 

furnaces and how existing furnaces are 

rebuilt. Incentives are also considered. 

Possible approach 

The aim of this study is to provide the 

data that the European Commission 

needs to determine what action to take. 

The main approaches being used after 

completion of previous eco-design 

studies are: 

• Legislation to ban the least energy 

efficient products 

• Minimum energy efficiency requirements 

• Energy labelling and improved performance 

information (possibly suitable 

for laboratory equipment) 

• Voluntary agreements by industry 

(this option is not popular with the 

furnace industry). 

Industrial and laboratory furnaces and 

ovens are however very different to the 


Reports 


types of product considered by previous 

studies and so alternative approaches 

are being considered. It is possible for 

laboratory standard designs to be regulated 

by minimum energy performance 

standards that will remove the least 

efficient products from the market. 

However an EU standard measurement 

method will be required first. For industrial 

furnaces and ovens, which include 

custom designs, it is not possible to regulate 

in this way and so the approach 

used in Japan is being considered. The 

Japan Energy Act imposes minimum performance 

targets on industrial furnaces 

such as the percentage of heat recovered 

from flue gases. A similar approach 

could be used in the EU but cover a wider 

variety of furnaces and ovens including 

all sizes and electrically heated as well as 

fossil fuel. Also, a wider range of performance 

parameters could be used. Regulation 

using a particular performance 

parameter is an option if it likely that it 

could result in a sufficiently large energy 

consumption decrease. Reliable data is 

essential to determine where eco-design 

requirements can be beneficial. If data is 

lacking however, the Commission could 

assume that improvement is achievable 

and impose requirements that achieve 

little environmental benefit but increase 

the costs of industry. 

Conclusion 

This study can be viewed by industry 

as either a threat or an opportunity. 

It clearly would constitute a threat if 

unsuitable legislation were to be introduced 

as a result of an incorrect understanding 

of the furnace and oven industry. 

Some industry sectors have had 

serious difficulties after completion of 

several previous studies where they did 

not become fully involved and provide 

the data that was required to develop 

workable eco-design options. 

There appear however to be enormous 

potential for reduction of energy consumption 

both by replacement of old 

furnaces and ovens as well as by installing 

new furnaces and ovens using 

the best technology that is available 

from manufacturers. A wide variety of 

novel technologies have been developed 

that can give large reductions in 

energy consumption which make processes 

more competitive by reducing 

the cost of energy throughout the life 

of furnaces and ovens. The study has 

identified examples where savings of up 

to 50 % are achievable by replacing old 

inefficient furnaces with new designs. 

There are also differences in the energy 

efficiency of new furnace designs. For 

example recuperative and regenerative 

gas burners are far more efficient than 

standard cold air burners and although 

these add to the price, payback times 

are relatively short. The main limitation 

on installing the most energy efficient 

processes appears to be limits on capital 

availability and this will not be easy to 

overcome. 

 

Dr. Paul Goodman 

ERA Technology Ltd 

Surrey (United Kingdom) 

Tel.: +44 (0) 1372 367221 

paul.goodman@era.co.uk 

Dr. Chris Robertson 

ERA Technology Ltd 

Surrey (United Kingdom) 

Tel.: +44 (0) 1372 367204 

chris.robertson@era.co.uk 


WIESBADEN 

12. – 14. Oct. 2011 



KNOWLEDGE 

for the 

FUTURE


Reports 

Simplified calculation of 

molten metal free surfaces in 

electromagnetic fields 

Part I: Mathematical model 


This is the first of a two-part paper which presents a simple simulation 

algorithm for an approximated free surface calculation of steady, electromagnetically 

driven molten metal flows. Based on a simplified treatment 

of the momentum equations, a Poisson equation is established 

by which the pressure can be calculated only based on the force density 

field. The free surface is determined by applying a linear pressuredependant 

approximation for the melt volume contained in the surface 

cells. At the free boundary, also the normal force density is considered 

within a proper computation of the electromagnetic field and pressure. 

Using an iterative inward gathering of the melt volume, the free surface 

is reconstructed under strictly volume conserving conditions, without the 

numerical creation of unphysical holes in the melt or of separated fluid 

droplets, respectively. Comparisons of computational and experimental 

results for the verification of model validity will be presented in the second 

part of the paper. 

The free surfaces of incompressible 

flows can be numerically simulated 

by the following, quite widely used 

methods: the Marker and Cell algorithm 

[1], the Volume of Fluid (VOF) method, 

based on the advection equation of a 

fractional volume function F [2], and the 

more recently developed versions of the 

VOF method, employing the transport 

equations of a local height function 

[3-5] or of the fluid volumes contained 

in multi-cell blocks [6, 7], respectively. 

The function F indicates the fluid fill of 

each computational cell, i.e. F E = 0 in 

the Empty (E) cells, 0 < F S < 1 in the 

partially filled Surface (S) cells and F F = 

1 in the completely filled Fluid (F) cells 

(Fig. 1). 

At small penetration depths of the 

electromagnetic field, the free surface 

contour can be obtained from the equilibrium 

of the electromagnetic pressure 

calculated by means of the magnetic 

field surface strength, the pressure due 

to the surface tension and the metallostatic 

pressure, respectively [8]. 

For simplification the free surface can 

be approximated by a Simple Line Interface 

Calculation (SLIC), i.e. by lines and 

planes parallel to the reference frame 

axes [2-7]. 

This first part of the paper establishes a 

simulation model for an approximated 

free surface determination of molten 

metal steady flows in electromagnetic 

field, by applying the finite difference 

(FD) method. Based on a convectionand 

diffusion-free treatment of the 

pressure containing momentum equations, 

a pressure Poisson equation is 

derived. By its solving, the pressure can 

be computed only based on the resulting 

force densities and subsequently, 

the free surface profile is constructed 

by using for the VOF function, a linear 

approximation dependent on pressure, 

and the SLIC method, respectively. 

The model can be applied at different 

penetration depths, e.g. at 30 kHz 

or 50 Hz, respectively. Experimental 

verifications in three laboratory setups, 

to be presented in the second part of 

the paper, have shown a relatively good 

agreement of calculations and measurements. 

Calculation of the electromagnetic 

field 

The sinusoidal electromagnetic field is 

determined in the molten metal by the 

magnetic vector potential A, considering 

in both the field and Lorentz force calculations 

all S cells as being completely 

filled with melt [5-7, 9]. In the regions 

free of eddy currents, the magnetic 

field can be computed only based on 

the magnetic scalar potential Ψ, when 

at the interface of the computational 

domains with the different potentials A 

and Ψ, the boundary conditions given in 

[10] have to be applied. 

Fig. 1: Cell labeling 


Reports 


Table 1: Calculation of coefficient k S , distance d and coefficient F MS 

in equations (5), (8) and (9), considering 

In an S cell, F S can be calculated based 

on the distance d between the free surface 

and the middle point M between 

the central points of the S cell and its 

adjacent F cell in the direction normal to 

the free surface, as follows: 

 

(5) 

An electric scalar potential can be used 

inside the melt such as to annul the normal 

eddy current density on the solid 

boundaries, e.g. on the inner crucible 

wall of an induction furnace, and also 

on the outer faces of the S cells, i.e. on 

their open sides to the E cells. 

Calculation of the pressure field 

By neglecting the convective and diffusion 

terms, the distributions at a new 

time level of velocity v and pressure p 

of an unsteady flow can be determined 

with the time-discretized momentum 

equation (1): 

 

(1) 

in which the superscript „new“ indicates 

a calculated new value, ∆t denotes 

the time step, ρ the density and f the 

resulting force density, respectively. 

Equation (1) can be solved by a two-step 

procedure according to eq. (2): 

Fig. 2: S Cell on an upper MHS 

 

(2) 

where v* represents the velocity of an 

intermediary flow field, which in a calculation 

with v = 0 for each time step, 

is given by eq. (3): 

 

(3) 

The imposing of the continuity condition 

div v new = 0 in equation (2) yields, 

together with equation (3), the following 

Poisson equation for the calculation 

of a steady pressure field [9]: 

div grad p = div f, (4) 

which is solved for all F and S cells by 

considering all S cells to be also completely 

filled [9]. 

Equation (4) is solved numerically by 

applying the homogeneous Neumann 

boundary condition to the solid walls 

and the outer faces of the S cells. On 

these boundaries, the normal velocity 

component of a steady flow is zero, v n = 

0. Therefore, according to equation (3), 

in the calculation of the right hand side 

of equation (4), the normal component 

of the force density is also set to f n = 0 

on the solid boundaries and on all S-E 

boundaries [9]. 

Partition of the free surface 

The free surface simulation will be presented 

for an axisymmetric flow when 

using the FD method for a uniform grid 

of size h. 

A free surface reconstructed by the 

SLIC method, e.g. of a levitated melt 

(Fig. 1) can be divided into several sections: 

a first lower More Horizontal Section 

(MHS) composed of horizontal line 

segments in the lower S cells with 1 ≤i ≤ 

i1, a second More Vertical Section (MVS) 

consisting of vertical line segments in 

the lateral S cells with j1 ≤ j ≤ j2, and a 

last upper MHS contained in the upper S 

cells with 1 ≤ i ≤ i2, respectively. 

k S being given in Table 1 for an S cell 

on both an MHS (Fig. 2) and an MVS 

(Fig. 3), respectively. 

Free surface displacement 

The free surface location can be defined 

based on the distances d or by the F S - 

values, respectively. The space-variable 

potential component of the force density 

will be assumed to be constant between 

the central points of two neighbouring 

F and S cells 

 

(6) 

and if the surface lies between M and 

the central point of the S cell, i.e. if d ≤ 

h/2 (Fig. 2 and 3), then linear interpolation 

can be applied to d as detailed in 

[9]: 

 

(7) 

In equation (7), p s represents the pressure 

at the free surface, calculated 

based on the ambient pressure p a and 

the pressure due to surface tension pσ 

[9] 

Fig. 3: S cell on an MVS 

(8) 

 

260 



Reports 

Table 2: Calculation of the VOF-function on an upper MHS (Fig. 2) [9] 

according to Table 3, where the ratios 

of radii consider the volume modification 

of the grid cells in direction r. 

where function max { }, which yields the 

greatest value of the two arguments, 

considers also the normal force densities 

f n exerted on the outer sides of the S 

cells (Fig. 2 und 3), which were not used 

in the discretized equations (4). Consequently 

(7) can be applied also for d > 

h/2. The distance d in equation (8) can 

be determined by the formulae given in 

Table 1. 

With (5), equation (7) can be rewritten 

as: 

(9) 

where F MS too is determined according 

to Table 1. Thus the F S -values can be 

obtained based on the p-values resulted 

from the numerical solving of equation 

(4). 

Conservation of the melt 

volume 

A constant can be added to the values 

of the pressure calculated by solving the 

Poisson equation with homogeneous 

Neumann boundary condition; or similarly, 

the constant C can be added to 

the surface pressure, such as to maintain 

the volume constant [9]. 

Upon replacing p s by p s + C in eq. (9), 

the corrected fractional volume can be 

written as: 

 

(10) 

By substituting equation (10) in the volume 

conservation equation 

 

(11) 

where the first sum is performed over 

all F and the second over all S cells and 

V m is the appointed melt volume, the 

constant results as: 

Free surface reconstruction 

 

(12) 

For each S cell, the calculated new preliminary 

F S -value, which further will 

be designated by F Sn , is conservatively 

redistributed as the VOF functions of the 

S cell and its adjacent cells. For example, 

if for the S cell (i, j) on an MHS (Fig. 2) 

F Sn results between 0 and 1, the corresponding 

VOF function will be assigned 

according to Table 2. For F Sn < 0, the S 

cell will be emptied and the fluid volume 

is inward gathered, thus preventing the 

numerical creation of artificial holes in 

the melt or of separated droplets. If 

F Sn > 1, the S cell will be completely 

filled and the volume excess is transferred 

normally to the MHS to its northern 

empty cell (i, j+1), as presented in 

Table 2. 

For the S cells on an MVS (Fig. 3), the 

F-values will be calculated similarly, 

Underrelaxation 

Since each reconstruction of the free 

surface generates a modification of the 

computed electromagnetic field, the 

steady form of the melt surface can be 

determined only by an iterative procedure. 

To guarantee the stability of the 

numerical algorithm and avoid the calculation 

of oscillations, within one iteration 

at the most one free surface portion 

can be displaced from an S cell to 

its adjacent cells. 

Therefore, in the F S -calculation by 

means of equations (9), (12) and (10), 

the following underrelaxation will be 

introduced for all S cells: 

F Sn = ω F Sc + (1 - ω ) F S , (13) 

where F Sn indicates a new iteration 

value, ω represents an underrelaxation 

factor and F Sc is obtained by equation 

(10) employing the constant (12). 

To avoid under- (F i,j < 0) or overshoots 

(F i,j > 1), limitations of the F Sn values 

have to be used, e.g. for the S cell 

shown in Fig. 2, F Sn must be restricted 

between F min = – 1 and F max = 2. On an 

MVS, Table 3 indicates the limits: F min 

= – r i–1 /r i and F max = 1 + r i+1 /r i , respectively. 

Substitution of these limits in (13) 

yields the following, maximal admissible 

factors [9]: 

ω S = 

(14) 

ω S = 

and the smallest ω S ≤ 1 obtained for 

all S cells will be further used in (13) as 

ω-value. 

Table 3: Calculation of the VOF-function on an MVS (Fig. 3) [9] 

Conclusion 

Successive computation of the electromagnetic 

field, the pressure distribution 

and correction of the free surface is 

performed until sufficient convergence 

is reached, e.g. until the absolute differences 

of two successive F S -iterations is 

smaller than 5.10 –4 for all S cells. 

The algorithm for free surface simulation 

comprises the following steps: 


Reports 


1. Indicate the source current densities 

in the inductor 

2. Evaluate the F-values for an initial 

free surface shape 

3. Repeat until sufficient convergence is 

reached: 

• Label the grid cells and divide the 

free surface in MHS- and MVSparts 

• Determine the distances d by using 

Table 1 

• Compute the electromagnetic 

field and the force density distribution 

• Solve the pressure Poisson equation 

(4) 

• Obtain the pressures (8) at the free 

surface 

• Calculate the F S -values (9), C by 

eq. (12) and the F Sc -values (10) 

• Find by means of eq. (14) the maximal 

admissible underrelaxation 

factor and determine the new F Sn - 

values (13) 

• Redistribute the F Sn -values according 

to Table 2 and 3. 

Literature 

[1] Griebel, M., Dornseifer, T., Neunhoeffer, 

T.: Numerische Simulation in der 

Strömungsmechanik. Braunschweig: 

Vieweg, 1995 

[2] Hirt, C.W., Nichols, B.D.: Volume of 

Fluid (VOF) Method for the Dynamics 

of Free Boundaries. Journal of Computational 

Physics 39 (1981) pp. 201-225 

[3] Gerrits, J.: Dynamics of liquid-filled 

spacecraft. Ph.D. Thesis, University of 

Groningen, 2001 

[4] Kleefsman, K.M.T., Fekken, G., Veldman, 

A.E.P., Iwanowski, B., Buchner, 

B.: A Volume-of-Fluid based simulation 

method for wave impact problems. 

Journal of Computational Physics 206 

(2005) pp. 363-393 

[5] Peşteanu, O., Baake, E.: Contribution 

to the simulation of free surface flows 

in electromagnetic field. 54th International 

Scientific Colloquium, Sept. 

2009, Ilmenau University of Technology, 

Conference Proceedings on USB- 

Flash, Session 7.1 

[6] Peşteanu, O., Baake, E., Nacke, B.: 

Beitrag zur Berechnung der freien 

Oberflächen von Flüssigmetallströmungen 

im elektromagnetischen Feld. 

elektrowärme international 67 (2010) 

No. 2, pp. 127-130 

[7] Peşteanu, O., Baake, E.: The Multicell 

Volume of Fluid (MC-VOF) Method for 

the Free Surface Simulation of MFD 

Flows. Part I: Mathematical Model. ISIJ 

Int. 51 (2011) No. 5, pp. 707-713 

[8] Westphal, E.: Elektromagnetisches und 

thermisches Verhalten des Kaltwand- 

Induktions-Tiegelofens. Diss., Fortschr.- 

Ber. VDI Reihe 21. Düsseldorf: VDI Verlag 

1996 

[9] Peşteanu, O.: Vereinfachte Berechnung 

mit dem Kraftdichtefeld der freien 

Oberfläche von Flüssigmetallströmungen 

im elektromagnetischem Feld. 

Tagungsband Workshop Elektroprozesstechik 

2010, TU Ilmenau, Report 3 

[10] Peşteanu, O., Baake, E., Nacke, B.: 

Induktives Schwebeschmelzen mit 

zwei Frequenzen. Tagungsband Workshop 

Elektroprozesstechnik 2004, TU 

Ilmenau, Report 8 

 

Prof. Dr.-Ing. 


Institute of Electrotechnology 

Leibniz University of Hanover 

Hannover (Germany) 

pesteanu@ 

etp.uni-hannover.de 

HK 

Please visit us 

at the colloquium 

for heat treatment 

in Wiesbaden, 

stand 133, hall 1 

12.10. – 14.10.2011 

Induction 

the next dimension. 

Induction hardening 

and heating equipment 

• Frequency converter powered 

• Process development 

• Induction heat-treatment shops 

• World-wide service 

• Inductor express service 

• Seminars/training programs 

INDUCTOHEAT Europe GmbH 

Ostweg 5 

D-73262 Reichenbach/Fils, GERMANY 

Phone +49 (0) 71 53 504-0 

www.inductoheat.eu 

YEARS 

Leading Manufacturers of Melting, Thermal Processing & 

Production Systems for the Metals & Materials Industry Worldwide 

Fiery innovation for hard-as-steel solutions


Reports 

Online frequency adjustment for 

energy optimization of induction 

hardening processes 

Alexander Ulferts, Frank Andrä 

It is frequently necessary to harden multiple points on a component. The 

hardness specification may, in many cases, be variable, and the boundary 

conditions often diverse. The relevant sectors of the component are in 

many cases more deeply hardened, to enhance strength and vibrationfatigue 

properties, with simultaneous retention of ductile properties in 

the core, in order to reduce the danger of fracture of the heat-treated 

component in service. In other cases, the hardening process is intended 

more to provide protection against elevated surface loadings and against 

abrasive erosion of material. Both of these applications are illustrated on 

the basis of a component in the context of this article, and the requirements 

made on the inductive hardening process discussed. The authors 

consciously raise the question of the limits of technical feasibility. 

frequency from the electrical, but temperature-dependent, 

material parameters 

[1] and [2]. 

 

(1) 

At the selected frequencies of 5 kHz and 

50 kHz, a ratio of between the 

resulting penetration depth is 

obtained: 

The following case is considered: A 

shaft made of C45 material (SAE 

1045) with a diameter of 20 mm must 

be inductively hardened at two different 

spots. For reasons of stability, area 1 

shall be hardened to a depth of 4 mm, 

to absorb the oscillating constant load 

acting on the shaft. Area 2 is a bearing 

seat and thus only to be hardened 

to 0.5 mm in order to reduce geometric 

distortions (Fig. 1). 

To evaluate the suitable frequency and 

the required power distribution to attain 

the targeted hardnesses, two target 

temperatures are respectively determined 

for the surface and for the lower 

area of the hardening zone. The depth 

of the hardening zone is estimated via 

the temperature gradients, in order to 

analyse the process using numerical 

modelling: 

At the surface, the final hardening temperature 

should be 990 °C (temp_o 

in the diagram). At the same time, 

the temperature at the lower area of 

the hardening zone should be 850 °C 

(temp_i in the diagram). The lower layers 

of the material are then subject to a 

reduction in hardness down to the basic 

hardness of the material. 

Both hardening points are subsequently 

observed during a hardening process 

with working frequencies of 5 and 

50 kHz respectively. The temperature 

cycles as the heating time progresses 

for the surface (temp_o) and the lower 

hardness area (temp_i) are analyzed and 

the overall energy required for the processes 

is calculated. 

A key factor to ensure the efficient 

attainment of hardening depths is the 

electromagnetic penetration depth, 

which can be derived in addition to the 

Fig. 1: Specimen component: shaft, d = 20 mm 

 

(2) 

Within the electromagnetic penetration 

depth, around 86 % of the power 

induced in the workpiece is converted 

into heat. This variable is thus decisive 

when it comes to setting the correct 

hardness penetration depth. 

Hardness area 1: 

Stabilization zone 

In the area of the stabilization zone, 

the objective is to harden to a depth of 


Reports 


Fig. 2: Hardening of the stabilization zone at a frequency of 5 kHz 

Fig. 3: Hardening of the stabilization zone at a frequency of 50 kHz 

4 mm. In Fig. 2, the heat-up curve for 

both of the previously defined measurement 

points can be realised at a working 

frequency of 50 kHz. The heating 

rate at the lower end of the target hardening 

zone is significantly lower than at 

the surface. From the Curie point, the 

heating rate increases noticeably, which 

means that both temperatures align and 

at the end of the heating process, the 

desired difference of 140 °C is configured 

(990 °C to 850 °C). In total, the 

entire heating process takes around 

2.4 s at a frequency of 50 kHz. 

If the working frequency is reduced by a 

factor of 10 from 50 kHz to 5 kHz, the 

difference between the heating rates is 

still apparent, but far less pronounced 

(Fig. 3). At the end of the heating process, 

the difference of 140 °C remains. 

However, the overall heating time at 

5 kHz increases from 2.4 s to 7 s. 

Based on the chronological power distribution, 

the resulting energy requirement 

allows us to conclude that implementing 

the hardening process at 5 kHz 

as opposed to the process at 50 kHz 

allows an energy saving of 27 %. 

For the inductive heat treatment of the 

stabilisation zone, the lower frequency 

of 5 kHz is more suitable; while the 

energy efficiency of the process at 5 kHz 

is clearly higher. 

Hardness area 2: 

Bearing seat 

In the area of the bearing seat, the 

objective is to harden to a depth of 

0.5 mm, to minimise the workpiece dis- 

tortions this area as far as possible. This 

is achieved by ensuring the heat impact 

as well as the martensite formation are 

as low as possible. Similarly, this application 

involved observation of the processes 

at 50 kHz and at 5 kHz. In general, 

at this point, there is a completely 

different distribution of results. 

Fig. 4 shows the heat-up curves of the 

material in the area of the bearing seat 

at the surface and at the lower area 

of the desired hardening zone for the 

working frequency of 50 kHz. Clearly 

noticeable here are the stronger heating 

rate at the surface and the clear 

temperature difference between the 

measuring points, which is configured 

at the end of the heat-up process to the 

previously defined level of 140 °C. The 

heating time in the process was 100 ms. 

Accordingly, the desired hardness pro- 

Fig. 4: Hardening of the bearing seat at a frequency of 5 kHz 

Fig. 5: Temperature difference in hardening of the bearing seat, 

frequency: 5 kHz 

264 



Reports 

at two different frequencies, which differ 

by a factor of 10 under optimal conditions. 

A change in frequency is thus 

required during the heat treatment process. 

In the classic case, two different 

oscillating circuit converters (5 kHz and 

50 kHz) are required for this purpose. 

The hardening process is thus broken 

down into two sub-processes. 

Fig. 6: Hardening of the bearing seat at a frequency of 50 kHz 

Fig. 7: Modulation of frequency across pulse length 

A new approach is the use of the Statitron 

iFP force-guided converter [3]. The 

converter frequency for this converter 

is no longer determined by the inductive 

and capacitive elements contained 

in the system, but is specified by the 

control of pulse width modulation. By 

changing the pulse length, the working 

frequency is freely adjustable, even during 

a heating process (Fig. 7 and 8). At 

the same time, a time-controlled adjustment 

of output by changing the duty 

cycle is also possible. 

Both hardening points of the shaft 

can therefore be inductively hardened 

in a process and setting via the online 

modification of frequency. In addition, 

the online frequency optimisation of 

the hardening process clearly leads to 

a more energy-efficient hardening process. 

If identical temperature distribution 

is maintained, savings of 27 % in 

terms of energy consumption are possible 

for the case in question. 

Literature 

Fig. 8: Modulation of power across pulse width 

file is reached without problem using 

this process. 

Reducing the working frequency from 

50 kHz to 5 kHz reveals a clear change 

in the quality of the heating. No longer 

is there any detectable difference 

between the heating rates at the surface 

and the lower layer of the hardening 

zone (Fig. 5). Referring to the detailed 

resolution image (Fig. 6) shows that at 

the end of the heating process, there 

is a difference of under 25 °C between 

the measurement points. This leads to a 

clearly deeper hardening as previously 

defined. Even with a short heating time 

of 100 ms, the hardness pattern is not 

attainable at the bearing seat with a frequency 

of 5 kHz. 

If we consider the energy requirement 

of both processes in question, it is found 

that the process at 50 kHz has an energy 

requirement 77 % lower than the process 

at 5 kHz. 

For the inductive heat treatment of the 

bearing seat, a working frequency of 

50 kHz shall be selected. The required 

hardness pattern is not attainable with 

a frequency of 5 kHz and even energetically, 

is incommensurate with the higher 

frequency process. 

Conclusion 

The existing workpiece shows two hardening 

points, which must be treated 

during the inductive hardening process 

[1] Benkowsky, G.: Induktionserwärmung 

[2] Rudnev, V.; Loveless, D.; Cook, R.; Black, 

M.: Handbook of Induction Heating. 

CRC Press, 2002. 

[3] Ulferts, A.; Andrä, F.: Innovation durch 

adaptive Frequenzvariation im Induktionshärten. 

elektrowärme international 

(2010) Nr. 3, S. 217-220. K 

Dipl.-Ing. 

Alexander Ulferts 

HWG INDUCTOHEAT 

Europe GmbH 

Reichenbach (Germany) 

Tel.: +49 (0) 7153 / 504 226 

ulferts@hwg-inductoheat.de 

Dipl.-Ing. Frank Andrä 

HWG INDUCTOHEAT 

Europe GmbH 

Reichenbach (Germany) 

Tel.: +49 (0) 7153 / 504 210 

andrae@hwg-inductoheat.de 


Reports 


Precise induction heating of Ti 

and Zr billets 

Victor Demidovich, Pavel Maslikov, Evgeniy Grigoriev, Vladimir Olenin, Irina Rastvorova 

Electromagnetic treatment of materials by induction is becoming more 

widely used in science and industry. The method of electromagnetic processing 

can be successfully used for melting and heat treatment of titanium 

and zirconium alloys. Different technologies using induction precise 

heating before plastic deformation are discussed in this paper. For alloys 

of many metals such as titanium, zirconium, niobium, tantalum, etc., it 

is important to provide precision heating with a high degree of homogeneity 

of the temperature field and strict adherence to the condition of 

heating. This is explained by polymorphism of these alloys, their chemical 

activity at high temperatures and the specific thermal and electrical 

properties. It is very important for induction heating to define the extreme 

achievable unevenness of the temperature field. Optimal control can be 

used for massive billets to reduce significantly the heating time, energy 

expenses and to improve the quality of the temperature field distribution. 

Optimization of induction heating process can be achieved by synchronous 

solution of the problem of optimal control and design. 

Technologies of induction heating 

find wide application not only for 

the now traditional heat treatment of 

steel, aluminum, copper, but also for 

heating of the titanium and zirconium 

alloys. Induction installations are widely 

applied for heating billets and slabs 

before rolling, reduction, straightening, 

and other types of plastic deformation. 

Besides, works on strengthening of 

titanium products are conducted. The 

introduction of induction heating in 

the processing line of titanium billets is 

explained by the following well-known 

advantages: good energy characteristics, 

a high heating rate, simple control, 

the possibility of complete automation, 

small unit dimensions, and easy maintenance 

(including the case of changes in 

the size of billet) [1, 2]. 

For many alloys of metals such as titanium, 

zirconium, niobium, tantalum, 

and some others, it is important to 

ensure the accuracy of heating with 

a high degree of homogeneity. This is 

explained by polymorphism of these 

alloys and narrow temperature range 

where high quality plastic deformation 

can be realized. Low thermal conductivity 

and high temperature losses at the 

surface result in maximum temperature 

inside of the billet that could not 

be measured by pyrometers. At the 

same time precise heating with very 

high homogeneity of the temperature 

field and strong execution of the temperature 

profile during the heating time 

are essential for thermal processing of 

these alloys before plastic deformation. 

Therefore, it is very important for induction 

heating to determine the maximum 

achievable uneven temperature field 

under real conditions of heating. In the 

case of critical components, when the 

plastic deformation is taken place in a 

very narrow temperature range (± 5 - 

10 °C), it is often used thermostats after 

heating in the inductor [3]. Nevertheless 

the precise induction heating could be 

realized in the stage heater. 

Requirements and peculiarities 

for heating billets from non-ferrous 

alloys by induction method 

Unlike steel heating titanium heating 

has features associated with the physical 

and chemical properties of the material 

and with high demands of consumers 

for quality products in accordance with 

international and national standards in 

aviation industry. 

Requirements for heating billets from 

non-ferrous alloys: 

• formation of an extremely possible 

uniform temperature field along the 

length and cross section of the billet; 

• exclusion of overheating the billet; 

• minimizing the heating time. 

Due to the skin effect in the billets during 

induction heating heat sources are 

distributed over the cross section of the 

billet non-uniformly: the maximum of 

heat sources are at the surface and the 

intensity of the heat sources is reduced 

with increasing distance from the surface. 

Accordingly, the surface layers have a 

higher temperature than the inner, and 

this temperature difference is greater, 

the greater the power of heating and 

the higher frequency of current. Heat 

losses from the outer surface qualitatively 

affect the nature of the temperature 

field in the cross section of the billet: 

due to heat losses from the surface 

the zone is formed in deep of the billet 

which has a higher temperature than 

the surface. This phenomenon is taken 

place during induction heating of metals, 

but for titanium alloys, it appears 

very bright because of the low thermal 

conductivity and high heat losses. Overheating 

of the inner layers of metal may 

lead to local changes in the structure 

of metal, to the appearance of residual 

stresses, and at high heating temperatures 

- to melt the internal layers. 

The typical temperature distribution in 

the cylindrical billet heated by induction 

method is illustrated in Fig. 1. During 

time t1 surface temperature with a 

high power of heating is considerably 

higher than the temperature at the center. 

Further power of induction heating 

decreases and the temperature difference 

between the surface and the centre 

is decreased, too. 

Due to heat losses from the surface 

maximum temperature during induc- 

266 



Reports 

Fig. 1: Typical distribution of temperature field during induction heating 

tion heating every time is located inside 

(Fig. 1). At the heating time t2 when 

the temperatures at the surface and in 

the center are equal, the temperature 

difference ∆T2=ε inf is the value that 

could not be less under this conditions 

of heating. The temperature difference 

∆T2=ε inf depends on final temperature 

of heating, diameter of billet, frequency 

of current, thermal conductivity of alloy, 

heat losses from the surface (quality of 

refractory). 

Two types of refractory were reviewed, 

which provide in stationary mode heating 

heat losses from the surface of the 

billet with coefficient of heat transfer 

α = 0.002 W/(cm 2 °C) and α = 0.006 

W/(cm 2 °C). Actual refractory that currently 

can be installed in the induction 

heaters provide conditions of heat losses 

lying in the specified range. 

For the comparison calculations of heating 

cylindrical titanium billets from alloy 

VT6 and diameter 120 mm in inductor 

were done. Simulations of heating bil- 

lets were done at frequencies 500 Hz 

and 1.000 Hz up to final temperature 

of heating 750 °C (Fig. 2). Both options 

were calculated for the coefficients heat 

transfer α = 0.002 to 0.006 W/(cm 2 °C). 

Specific power was chosen in such a 

way that at the end of the heating surface 

temperature and the temperature 

in the center were identical and equal. 

Fig. 2 shows the temperature distribution 

in the titanium billet at the end of 

the heating. For low-temperature heating 

(700 to 800 °C) and small (

Reports 


length of the billet. In most real induction 

devices end effects of the inductor 

and the billets are superimposed 

on each other and with a small length 

of the heated product or winding are 

also the imposition of distortions arising 

from both ends of the elements of the 

system. 

To achieve the maximum allowable distribution 

of temperature field along the 

diameter and length of the billet different 

methods of optimal control are used 

during heating. These include the choice 

of frequency, the choice of the necessary 

power and heating time, passive 

and active spatial means of regulation. 

The most known electrical means of 

temperature regulation are: using end 

effect of inductor and billet, the Faraday 

rings, additional inductors at the ends 

of coil, concentrators, etc. This means 

influences on the power distribution 

along length of billet and properly on 

the temperature field. To obtain a more 

uniform temperature field in the case of 

multi-layer coil it can be used different 

coil winding step on the outer layers of 

the heater. At the ends of the inductor 

denser winding is used. In this case, the 

power is fed more in the ends of the 

billet, which contributes to the heating. 

In some cases, such as when one coil 

is used for heating billets of different 

lengths sites with more dense and winding 

sections with less dense winding are 

symmetrically alternated on both sides 

of the inductor, thus provides a relatively 

uniform heating along the length 

of the billet. 

When we heat solid cylindrical billets, 

flat heater can be installed in the end 

of the inductor. To control the tem- 

Fig. 4: Maximum 

achievable uneven 

temperature field 

vs σ without (1) 

and with thermal 

refractory at 

the edges of 

inductor (2) 

perature distribution power supply of 

the butt heater can be carried by either 

AC voltage, taken from the primary coil, 

either DC or AC voltages of any frequency. 

Power supply of the butt heater 

can be carried by electromagnetic coupling 

with an additional inductor winding, 

ends of which are attached to both 

ends of the resistive heater. Additional 

inductor may have an independent 

power source. The thermal compensators 

can be implemented in the form of 

closed rings from heat-resistant conductive 

material and can be installed inside 

the inductor at the end zones of the lining. 

During heating simultaneously with 

the main coil, they create a heat shield, 

thereby reducing heat losses from the 

face side billet. 

Examples of a precise heating 

of the Zr billet in the stage 

induction heater 

For heating of preparations of various 

length in one inductor, it is necessary to 

supply it with different methods of optimal 

control of blank’s temperature field. 

As a variant for change of flooring current 

density in butt-end areas of billet it 

is possible to use the two-layer inductor 

which inside layer is made with constant 

step of coil winding, and external has 

ruptures. Three areas of coil winding are 

thus formed: the central area and two 

outer, arranged symmetrically about the 

inductor’s center. The length of ruptures 

gets out such that the billet’s length 

with the minimum length was equal to 

length of the central area, and butt-end 

of blank with the maximum length coincided 

with edges of outer areas. 

Thanks to such ruptures’ arrangement 

of the coil‘s second layer distribution of 

current density flooring on billet‘s length 

so that to reduce influence of inductor‘s 

and blank‘s edge effect at change of billet‘s 

length is made. The heating quality 

depends on the billet’s length. In case 

of short billet heating completely is provided 

with the coil winding of central 

area. For long billet the coil winding of 

central area provides heating only a regular 

zone. Heating the end zone is due 

to the outer areas of the coil winding of 

the second coil’s layer. Such design of 

an inductor is characterized by that the 

Fig. 5: Resistance of the inductor’s turns and final temperature distribution in the billet 

268 



Reports 

average detail’s part has the greatest 

temperature, and it excludes overheating 

and possible fusion of billet on some 

distance from its surface. 

Fig. 5 shows the distribution of final 

temperature field of zirconium billet 

with a diameter 220 mm and a length 

of 475 mm after induction stage heating. 

Final temperature is 1.000 ºC. It 

is necessary to ensure the maximum 

allowable accuracy of heating ± 20 ºC. 

This is achieved through the usage of 

optimal regime of heating, choice of 

optimal design of the stage induction 

heaters and the usage of different spatial 

controls temperature field means. 

The induction heater is a two-layer 

coil with a refractory to reduce heat 

losses from its surface. Heat shields are 

installed on the ends of the inductor to 

reduce heat losses by radiation from the 

ends of the billet. The second layer of 

the inductor consists of several symmetrically 

located relative to the center of 

turns at each end of the coil. This allows 

enhancing electromagnetic field at the 

ends of the inductor to compensate 

for end effects. Heating is carried out 

in two stages. The first stage is accelerated 

heating of billets with a maximum 

power at 60 Hz, and then the mode of 

thermostatic is activated at minimum 

capacity to equalize the temperature 

field and compensate heat losses from 

the surface of the billet. Thus it is possible 

to achieve the desired heating 

temperature 1.000 ºC with a specified 

accuracy of ± 10 ºC (Fig. 2). 

As can be seen from the Fig. 5, the absolutely 

homogeneous distribution of temperature 

field cannot be reached, but 

we can maintain the utmost attainable 

unevenness temperature distribution 

for a given billet in the desired range, 

as well as the difference between the 

temperatures Ts, Tc and T3 is minimal. 

Furthermore, using modern software 

package UNIVERSAL [2,3], make it pos- 

Fig. 7: Scheme of thermocouples’ installation along the billet’s length in diameter of 100 mm 

For this purpose was developed and 

implemented a precise heating system 

of long billets of titanium alloys by 

induction method. 

System of induction heating, consisting 

of eight identical inductors length 530 

mm, mounted on one axis and equidistant 

from each other equal to 340 mm, 

was developed. There are rollers 100 

mm in diameter to move the workpiece 

between the inductors. Billet does oscillating 

motion in the area of the inductors 

with amplitude of 870 mm (Fig. 6). 

For the case of heating with oscillating 

motion, the temperature field distribution 

along the billet length has a wavesible 

to simulate not only the temperature 

field distribution along the length 

and cross section of the billet, but also 

display the values of resistance in the 

turns of the inductor, which contributes 

to greater accuracy in the model of 

induction heater. 

Distribution of the resistance of the 

inductor’s turns in different layers is presented 

in Fig. 5. 

Coils’ resistance of the outer layer is 

lower than the resistance of turn’s inner 

one, which explains the ring and proximity 

effects. Coils’ resistance inner layer, 

located opposite the turns of the outer 

layer, increases, which is also explained 

by the redistribution of current over the 

cross sections of turns. 

Precise induction heating of 

long Ti billets [4,5] 

The method of induction heating of 

long billets subjected to oscillating 

motion in several induction heaters 

can be an alternative to heating a billet 

in one induction heater, where the 

billet motion along the guides is often 

difficult because of a large billet weight 

or length. In this case, a billet moves continuously 

and periodically changes the 

motion direction to the opposite one. A 

Fig. 6: Schematic 

diagram of an 

induction oscillating 

furnace 

billet is heated in several induction heaters 

spaced apart along one axis. Rollers 

are placed between the induction heaters 

for easy billet motion, and the billet 

oscillates in the induction heater zone at 

certain amplitude (Fig. 6). 

Reduction of an induction heater‘s 

dimensions s achieved by using heating 

of long-length titanium billets with the 

organization of the oscillating motion 

in several inductors. The given heating 

way is characterized by following advantages: 

• convenience of billet‘s moving in 

a heater, including loading and an 

unloading; 

• rather small heater’s sizes; 

• independence of billet‘s heating rate 

of a following technological process’ 

speed; 

• maintenance of the maximum 

achievable uneven temperature field, 

realization of the precise induction 

heating; 

• possibility of heating in protective 

atmosphere. 


Reports 


like character with a certain period. To 

measure the temperature distribution 

along and across the billet, it is sufficient 

to measure the temperature drop at 

three or four points in a small segment 

equal to the oscillating amplitude. 

Based on numerical simulations the 

scheme of thermocouples’ installation 

for an estimation of non-uniformity of 

heating has been developed (Fig. 7). 

Thermocouples t1, t4, t6, t8 have 

been established in the billet on depth 

50 mm, t2, t5, t7 – on depth 10 mm, 

t3 – on depth 5 mm. In the beginning of 

the heating process the thermocouple 

t3, t4 and t5 settled down in the distance 

center between inductors. The 

thermocouple t8 is necessary for an estimation 

of influence of edge effects on a 

detail end face. The measured temperature 

non uniformity along and across 

the billet is within 20 °C. General view 

of the induction heater for heating longlength 

billets is shown in Fig. 8. 

Conclusion 

The problems of precise induction heating 

of billets from alloys of non-ferrous 

metals such as titanium, zirconium, 

niobium, tantalum, and some others, 

are discussed in the paper. Induction 

heating of non-ferrous alloys has some 

features that it is necessary to take into 

account on the designing of equipment 

and the technology. Low thermal conductivity 

and high temperature losses 

at the surface result in maximum temperature 

inside of the billet that could 

not be measured by pyrometers. At the 

same time precise heating with very 

high homogeneity of the temperature 

field and strong execution of the temperature 

profile during the heating time 

are essential for thermal processing of 

non-ferrous alloys before plastic deformation. 

With all the known benefits of the 

induction heating technology it is necessary 

to note the impossibility of achieving 

absolute uniformity of temperature 

fields in the billets due to the difference 

in temperature between the environment 

in the inductor and the final temperature 

of the billet. 

Specific examples of optimal heating of 

zirconium billet in the two-layer stage 

induction heater and continuous heating 

of long-length titanium billet in 

several inductors are presented in the 

paper. 

Fig. 8: General view 

of the induction 

heater for heating 

long-length billets 

The decision of the given problems 

would be impossible without numerical 

simulation, because mathematical simulation 

is necessary part of equipment’s 

designing and development of technology. 

Using of the software packages UNI- 

VERSAL and COIL [2,6] allows designing 

induction systems for precise hightemperature 

heating of alloys of various 

metals with high accuracy and low cost 

of time. With the help of these programs 

the user can receive all required 

characteristics of induction system, 

including distribution of the temperature 

and electromagnetic fields in loading, 

power, electrical efficiency, power 

factor, current of inductors etc. 

Literature 

[1] V. Demidovitch, B. Nikitin, V. Olenin: 

Induction Installations for Heating Long 

Cylindrical Billets Before Metal Forming 

// Russian Metallurgy. 2007, N o 8. p. 

98-102. 

[2] V. Nemkov and V. Demidovitch: Theory 

and Computation of Induction Heating 

Devices, 1988, p. 288 (in Russian). 

[3] V. Demidovich, F. Chmilenko, B. Nikitin, 

V. Olenin, E. Grigoriev: Electromagnetic 

processing of titanium alloys before 

plastic deformation / Proceedings 6 th 

International Conference on ELECTRO- 

MAGNETIC PROCESSING of MATERIALS 

EPM2009, 2009, Dresden, Germany, pp. 

181-184. 

[4] V. Demidovich, V. Olenin, F. Tchmilenko: 

Method of induction heating of the long 

billets, Patent # 2333618 Russian Federation, 

2008. 

[5] V. Demidovitch, B. Nikitin, V. Olenin: 

Utilization of Induction Heating In the 

Titanium Industry, XVI International Congress 

on Electricity applications in modern 

world, Krakov, 2008, pp. 51-52. 

[6] V. Demidovich, F. Tchmilenko, E. Grigoriev, 

P. Maslikov, I. Rastvorova: Simulation 

of electromagnetic and temperature 

fields with stage induction heating of 

cylindrical non-magnetic billets // Induction 

heating №4(14), 2010, p.13-18. (in 

Russian). 

 


Victor Demidovich 

Sankt-Petersburg 

Electrotechnical University 

St. Petersburg (Russia) 

Tel.: +7 812 3803390 

vbdemidovich@mail.ru 

Ing. Pavel Maslikov 




Tel.: +7 812 3803390 

pmaslikov@gmail.com 

Ing. Evgeniy Grigoriev 




Tel.: +7 812 3803390 

eagrigoriew@bk.ru 

Dr.-Ing. Vladimir Olenin 




Tel.: +7 812 3803390 

oleninv@mail.ru 

Ass. Prof. Dr.-Ing. 

Irina Rastvorova 

North-West Technical 

University 


Tel.: +7 921 7593866 

rastvorova@mail.ru 

270 


MEASUREMENTS & PROCESS CONTROL 

Reports 

Impact of measurement errors 

on the results of nitriding and 

nitrocarburizing treatments 


We have a pretty good idea of what will happen to steel parts if exposed 

to a defined atmosphere at a given temperature. In order to determine 

the process parameters we can use the well-known Lehrer Diagram if 

we plan for a nitriding process, or we might use one of the various Fe- 

N-C phase diagrams in case of a nitrocarburizing process. All of the diagrams 

mentioned are giving the phase boundary between alpha iron and 

gamma prime nitrides as well as the phase boundary towards epsilon 

(carbo)-nitrides as a function of the nitriding and the carburizing potential 

and the temperature. In addition we also have to account for the shifting 

of the phase boundaries typically given for pure iron caused by the alloying 

elements in real parts made from steel. But what will happen to our 

parts if we encounter deviations between the actual parameters and the 

set values during control? 

This article will show typical measuring 

errors caused by the technique 

of the analyzers used and caused by 

a faulty reading of the temperature 

respectively caused by temperature 

deviations throughout the load and 

explain their influence on the outcome 

of the heat treatment. 

Below this precipitation layer we find 

the base material. 

At nitrocarburizing not only nitrogen 

but also carbon will be induced into the 

parts surface. This causes a more rapid 

growth of the white layer. Nitriding processes 

are typically aiming for a deep 

load bearing diffusion layer with only a 

little white layer whereas nitrocarburizing 

is used to create corrosion and abrasion 

resistant white layers. Nitriding is 

typically carried out at temperatures in 

the range of 480 °C to 550 °C, nitrocarburizing 

in the range of 570 °C to 

590 °C. 

Potentials and process 

parameters 

Both, nitriding and nitrocarburizing can 

be performed with different processes 

that are according DIN EN 10 052 classified 

into gaseous, salt, powder and 

plasma nitriding depending on the 

nitrogen bearing medium used. This 

article will focus on gaseous nitriding 

where ammonia is used to provide the 

nitrogen. 

The basic nitriding reaction is the catalytic 

dissociation of the ammonia molecule 

on the parts surface. 

Nitriding and Nitrocarburizing 

The target of a nitriding treatment is an 

enhancement of the mechanical and 

chemical properties of parts by inducing 

nitrogen into the parts surface. Depending 

on the requirements we are aiming 

for different types of layers. Fig. 1 gives 

a schematic structure of a nitrided layer. 

Starting from the surface we first 

observe a thin and very hard ceramic 

layer that has been formed by the transformation 

of the base material into iron 

nitrides. Below this so-called white layer 

we find a zone, saturated with nitrogen 

but not yet transformed into iron 

nitrides. This layer is known as diffusion 

layer. Within the diffusion layer there 

are precipitations of non-iron nitrides, 

which are nitrogen compounds with 

nitride forming alloying elements such 

as chromium, titanium or aluminum. 

Fig. 1: Schematic structure of a nitrided layer [1] 


Reports 


NH 3 → 1,5 H 2 + [N] (1) 

The effectiveness is defined by the 

nitriding potential K N as: 

 

(2) 

The phase diagram developed by Lehrer 

(Fig. 2) displays the phase boundaries in 

the Fe-N binary system as a function of 

temperature and nitriding potential. 

At nitrocarburizing a carburizing gas is 

added to the ammonia. For this reason 

there is also a carbon uptake besides the 

nitrogen uptake. The carburizing effect 

can also be explained by the reactions 

taking place on the parts surface. 

Fig. 2: Fe-N Lehrer Diagram 

with iso-concentration-lines 

for Nitrogen in the Epsilon 

phase [2, 3], nitriding potential 

K N in bar -0.5, temperature 

in centigrade 

We distinguish between the Boudouard 

reaction 

2 CO → CO 2 + [C] (3) 

with the according carburizing potential 

 

(4) 

and the heterogeneous water gas reaction 

H 2 + CO → H 2 O + [C] (5) 

with the according carburizing potential 

 

(6) 

It has to be noted that the two potentials 

K CB and K CW differ in magnitude 

while having the same nitriding effect. 

In addition, the heterogeneous water 

gas reaction is much faster compared to 

the Boudouard reaction. These relations 

have to be considered when picking the 

control parameters associated with the 

measurement system used. 

The impact of the combined nitriding 

and carburizing potentials K N and K CW 

on the composition of the white layer 

has been described by Weissohn [1] in 

his NICARM Diagram (Fig. 3). 

Measuring systems in use 

Different measuring systems can be used 

to detect the atmosphere potentials. 

The nitriding potential can be determined 

directly by measuring the partial 

pressures of ammonia and hydrogen in 

the process atmosphere. Typically, especially 

in regular nitriding processes it is 

sufficient to measure only one of the 

two components, as the other one can 

be easily derived out of the thermal dissociation 

of the ammonia. 

NH 3 → 0.5 N 2 + 1.5 H 2 (7) 

If, besides ammonia and pre-dissociated 

ammonia, nitrogen is added to the 

process atmosphere we either have to 

know the inlet gas flows or we have to 

measure both, hydrogen and ammonia. 

In oxi-nitriding processes air is added, 

causing a reaction of the oxygen with 

hydrogen. This creates water steam that 

shifts the percentages between the gas 

components and the nitrogen added 

with the air causes a dilution. Therefore 

we as well either have to know the inlet 

gases or we additionally have to measure 

the water content of the process 

gas. 

At nitrocarburizing with CO, CO 2 , 

Endogas or Exogas the bound oxygen 

is added beside the carbon and in the 

case of Endo- or Exogas also hydrogen 

and nitrogen will be injected into the 

furnace. This will establish the water gas 

equilibrium 

H 2 + CO 2 → H 2 O + CO (8) 

with the thermodynamic equilibrium 

constant 

Fig. 3: Fe-N-C NICARM Diagram for 575 °C with iso-concentration-lines for Nitrogen and 

Carbon in the Epsilon phase [1], nitriding potential KN in bar -0.5, carburizing potential 

KCW in bar 

 

(9) 

272 



Reports 

To calculate the carburizing potential(s) 

we also have to determine CO or CO 

and CO 2 . This can be done by a direct 

measurement of the gas component(s) 

or by measuring the inlet mass balances. 

The measuring systems regarded in the 

following consist of: 

• a H 2 analyzer using a measurement 

of the thermal conductivity of the 

process gas respectively 

• an infra red analyzer to measure 

ammonia, as an alternative to the H 2 

analyzer or as an addition 

• for the nitrocarburizing process we 

use an additional oxygen probe or 

alternatively 

• a CO – CO 2 infra red analyzer. 

Typical errors when measuring 

hydrogen 

When using an analyzer that derives 

the hydrogen content of a gas mixture 

by measuring the thermal conductivity 

there are three effects that influence the 

quality of the measurement: 

• temperature stability – the thermal 

conductivities of the various components 

in the sampling gas change in 

a differently way when exposed to a 

shift in temperature 

• pressure stability – basically the thermal 

conductivity of gases is stable in 

a wide range of pressure but there 

are still little deviations 

• viscosity – the thermal conductivity of 

a gas mixture is not represented by 

the sum of the thermal conductivities 

of the gas components but is curved 

by viscosity of the gas mixture. 

On top of this there are the built-in failures 

of a measuring system caused by 

the design and the sensor system used 

in the instrument, notably: 

• resolution, linearity and drift of the 

analog circuit 

• thermal stability of the sensor, longtime 

drift 

• deviations in the sampling gas flow 

But there is one error that is even worse. 

Analyzers of this type are calibrated on a 

binary gas mixture, typically on percentage 

hydrogen in nitrogen (% H 2 :N 2 ). 

When measuring the process gas of a 

nitriding or nitrocarburizing process we 

measure a mixture of hydrogen, nitrogen, 

ammonia and additional gases like 

carbon monoxide, carbon dioxide and 

water vapor. This causes a notable devi- 

Fig. 4: Determination of the total uncertainty out of a combination of two influencing 

variables 

ation of the interpreted H 2 -content to 

the real hydrogen percentage. 

If we have a closer look on an analyzer 

that is within a higher cost range, the 

manufacturer states for a measuring 

range of 0-100 % H 2 :N 2 : 

Output signal variations: 

< +/- 0.75 % of the lowest 

possible measuring range 

Zero drift: 

< 1 % per week of the lowest 

possible measuring range ... 

Repeatability: 

< 1 % of the selected measuring range 

Linearity deviations: 

< +/- 1 % of the selected meas. range 

This translates into an uncertainty of 

+/- 1.54 % H 2 :N 2 absolute. In addition 

we have to account for other influences 

such as environmental temperature, 

sampling gas flow and pressure, power 

supply voltage and a zero offset caused 

by other gases besides nitrogen and 

hydrogen. Fig. 4 gives an example how 

the total uncertainty of an instrument is 

calculated. 

Exaggerating, if we use this analyzer 

outside of a temperature and air pressure 

controlled chamber we will have 

Fig. 5: Deviations of measured H 2 :N 2 values to the real hydrogen percentage caused by cross 

sensitivity versus Ammonia; sampling gas measured at 100 °C 


Reports 


NH 3 + H 2 O + CO 2 → NH 4 HCO 3 (11) 

These effects result into a false measurement 

in the range of +/- 2 % absolute 

compared to the real ammonia content 

in the process gas. 


with an oxygen probe 

Fig. 6: Deviations of measured H 2 :N 2 values to the real hydrogen percentage caused by cross 

sensitivities given in a nitrocarburizing atmosphere and an established water gas equilibrium; 

sampling gas measured at 100 °C 

different readings during summertime 

and wintertime. The offset caused by 

ammonia is shown in Fig. 5, the deviations 

of a measurement of a nitrocarburizing 

atmosphere are shown in Fig. 6. 


ammonia 

When measuring ammonia with an 

infra red analyzer we have to account 

for some fundamental problems besides 

the deviations given by the mechanical 

and electrical design. At an IR measurement 

there is a linear dependency of 

the measured value on pressure. Therefore 

the pressure either has to be stabilized 

or measured and compensated 

for. The biggest error can be expected 

by the cross-sensitivity to water vapor. 

The comparably small absorption lines 

• Zero drift – especially when using 

Lambda probes we have to take into 

account that such instruments typically 

show 12 to 50 mV when measuring 

air instead of the expected 0 

mV. 

• Thermo voltage – if an in-situ probe 

is using different metals for the inner 

and the outer electrode used to pick 

up the voltage there will be an error 

that changes with temperature. 

• Catalysis – at the tip of an oxygen 

probe there might be a catalytic disof 

the ammonia are placed in a comb 

of water lines and an accurate detection 

of the ammonia lines can be done only 

by applying high-tech and high-cost 

efforts. For this reason we typically use 

a simple trick – the sampling gas is dried 

before being passed through the analyzer; 

in other words the water is taken 

out. But this as well causes two errors in 

the measured values: 

• as the water content is taken out it 

will shift the percentages of the other 

gases in the sample. 

• If the water is filtered out by condensation, 

it will react with ammonia to 

ammonium hydroxide (reaction 10) 

respectively in presence of carbon 

dioxide it will form ammonium bicarbonate 

(reaction 11). 

NH 3 + H 2 O → NH 4 OH (10) 

The measuring principle of an oxygen 

probe is based on the effect that zircon 

dioxide gets permeable for oxygen 

ions at temperatures above 350 °C. If 

the two sides of a zirconia element are 

exposed to different oxygen partial pressures 

there will be ionization and then a 

diffusion of the ionized oxygen atoms 

from the side with the higher oxygen 

partial pressure to the side with the 

lower oxygen partial pressure. In this 

way equilibrium is established where the 

charge displacement created by the ions 

corresponds to the gradient in the oxygen 

partial pressures on the two sides 

of the element. The charge displacement 

can be measured as a voltage. If 

the oxygen partial pressure on one side 

of the element is known (reference), the 

oxygen partial pressure on the other 

side of the element (sample gas) can be 

calculated out of the measured cell voltage 

and the cell temperature (Fig. 7). 

The relation between partial pressure 

gradient, temperature and expected 

voltage is given by the Nernst’ Equation 

(12). R is the universal gas constant, F 

is the Faraday constant and T is temperature 

in Kelvin. If the reference is 

operated with air, p 0 O 2 has to be set 

to 0.209. 

 

(12) 

The reading will be affected by the following 

effects: 

Fig. 7: Principle of 

an oxygen probe 

made from zircon 

dioxide [4] 

274 



Reports 

sociation of the ammonia. This will 

cause higher voltages as expected. 

• Unknown, sometimes not stable cell 

temperature – when using probes 

that are not equipped with an internal 

thermocouple, the Nernst’ Equation 

has to be solved with an estimated 

temperature. Even if this temperature 

has been determined by a calibration, 

this temperature might change during 

the process and lead to wrong 

assumptions in the measured partial 

pressures. 

• Measurement current too high – oxygen 

probes operate like a voltage 

source. If the analog input circuit 

of the measuring instrument has an 

input resistance that is too low, the 

measurement current will exceed the 

current supplied by the ion diffusion. 

This effect causes too low voltage 

readings. 

• Electron conduction – zirconium 

dioxide has the electrical property 

of an NTC resistor. The higher the 

temperature the more the cell will 

get conductive, causing an electron 

current that decreases the expected 

Nernst’ Voltage. 

Table 1: Effects of measurement errors with oxygen probes 

Table 1 shows the effect of measurement 

errors on the determined oxygen 

partial pressure. The deviations do not 

look impressive if compared with the 

absolute magnitude of the measured 

partial pressures but in a nitriding or 

nitrocarburizing process the oxygen 

partial pressure is used to calculate the 

amount of water vapor and is also used 

to calculate the partial pressure ratio 

between CO and CO 2 in the furnace 

atmosphere. 

Water vapor and hydrogen are in relation 

to oxygen following the reaction 

H 2 + ½ O 2 → H 2 O (13) 

and establishing the thermodynamic 

equilibrium 

 

(14) 

With respect to the potentials K N and 

K CB this might lead to considerable deviations, 

shown in Table 2 and 3. 


CO and CO 2 

The measurement of CO and CO 2 is 

typically performed by using an infrared 

analyzer, just like the measurement of 

ammonia. Therefore we have to account 

for the same inbuilt errors based on the 

general design. In addition we have to 

ensure that the analyzer is ammonia 

resistant. The measuring range has to 


Reports 


Table 2: Effects of O 2 measurement errors on the derived nitriding potential in an ammonia 

atmosphere with 5 % Air addition 

Table 3: Effects of O 2 measurement errors on the derived carburizing potential in an ammonia 

atmosphere with 10 % CO 2 addition 

match the conditions of a nitrocarburizing 

atmosphere. 

The accuracy or better to say the uncertainty 

of the measurement will easily be 

in a range of several percent of the measuring 

range. 

On top of the uncertainty of the analyzer 

we might encounter a shift from CO to 

CO 2 and vice versa as together with H 2 

and H 2 O the gas will try to establish the 

water gas equilibrium at the sample gas 

temperature, this prefers higher CO 2 

Fig. 8 displays the relative deviation of 

the determined nitriding potential comand 

lower CO percentages as present in 

the furnace. This effect will end in big 

deviations in the determined carburizing 

potential. 

In a nitrocarburizing process at 580 °C 

and an inlet gas mixture of 90 % 

ammonia and 10 % carbon dioxide 

with a controlled nitriding potential of 

KN = 1 and a set carburizing potential 

of K CB = 0.16 a shift of ½ % from CO 

to CO 2 will change to measured K CB to 

0.10. 


temperature 

When measuring temperature we first 

have to have a look on the specification 

of the components used. Thermocouples 

as well as measuring instruments 

have classified maximum deviations. 

Assuming that in nitriding and nitrocarburzing 

furnaces the typical thermocouple 

in use would be a type K thermocouple 

the allowed for measuring error is 

+/- 1.5 °C, according DIN IEC 584 – class 

1. If the thermocouple is connected to a 

high precision measuring instrument of 

class 0.1, we have to allow for another 

0.1 % of the measured temperature. At 

580 °C this sums up to an uncertainty 

+/- 2 °C absolute. 

Next are obviously as well effects like 

long time drift but also deviations at the 

measurement of the reference temperature 

at the terminal block of the instrument. 

Independent of the quality of the measuring 

system we have to account for 

remarkable deviations between the parts 

in the load. The AMS 2750 D allows 

for a maximum deviation of +/- 3 °C 

throughout the hot zone in a furnace, 

using a class 1 industrial furnace. 

Impact on the result of a 

treatment 

How much do such errors influence 

the result of a real treatment? We will 

first have a look on a nitriding process, 

nitriding potential controlled and using 

a hydrogen analyzer to measure the 

potential. Formula 7 gives the way how 

to calculate residual NH 3 from the measured 

H 2 percentage, KN will be derived 

using formula 2. 

The confidence limits can be estimated 

as: 

(pNH 3 – E 1 )/(pH 2 + E 2 ) 1.5


Reports 

dow while on the other hand the nitriding 

potential is nearly not affected. 

Generally spoken, for nitrocarburizing 

processes it is the best not to control 

potentials close to the phase boundaries 

but rather try to find an operating setpoint 

that will create the desired structure 

over a wide tolerance band. 

Fig. 9: Effects of measurement errors in hydrogen percentage and temperature on the Fe-N 

phase diagram. The dashed lines display the uncertainty range beside the phase boundaries 

to gamma prime and epsilon 

Consequently, when performing processes 

where the nitriding potential 

has to be controlled close to one of the 

phase boundaries this fuzzy range has to 

be taken into account. The same applies 

as well for nitrocarburzing processes. 

To clarify this effect, Fig. 10 displays 

a section within the three dimensional 

temperature - nitriding potential – carburizing 

potential diagram ensuring the 

formation of an epsilon white layer. We 

can see that with increasing temperature 

we have to increase the carburizing 

potential to stay within the control winpared 

to the real nitriding potential as a 

function of measuring errors in hydrogen. 

As both errors, E 1 and E 2 practically 

come to a doubled error – too low 

hydrogen reading will automatically 

cause too high ammonia reading and 

vice versa – it might be an advantage 

to use an additional ammonia analyzer, 

but not necessarily. 

When applying the allowed for measuring 

errors on the Lehrer Diagram we 

come to fuzzy phase boundaries. Fig. 9 

shows the impact of an error of +/- 1 % 

hydrogen and +/- 5 °C. 

Conclusion 

When using the available instrumentation 

used to measure and control nitriding 

and nitrocarburizing atmospheres 

we might observe remarkable deviations 

from the desired outcome. Besides obvious 

reasons like a passivation that has 

not been removed completely by the 

cleaning process these deviations might 

also be caused by the measuring and 

control system or by temperature deviations 

within the furnace. 

The article explains clearly how relatively 

small errors within the process chain 

sum up and might therefore lead to 

unexpected results of a heat treatment. 

For this reason it is essential to choose 

process parameters that account for 

the allowed uncertainties of the equipment 

used. Those errors will sum up and 

end in a fuzzy range around the phase 

boundaries of the Fe-N respectively Fe- 

N-C diagrams that are used to determine 

the atmosphere potential setpoints. 

The parameters finally used to control 

the treatment should be chosen in such 

a way that a sufficient safety distance is 

maintained. 

Literature 

[1] Weissohn, K.H.; Winter, K.-M.: Nitrieren 

– Nitrocarburieren, Gaswärme International, 

8/2002; p. 328-336 

[2] Lehrer, E.: Über das Eisen-Wasserstoff- 

Ammoniak-Gleichgewicht. Zeitschrift für 

Elektrochemie 36, 1930, p. 383-392 

[3] Spies, H.-J.; Berg, H.-J.: Zimdars, H.: 

Fortschritte beim sensorkontrollierten 

Gasnitrieren und nitrocarburieren. 

Zeitschrift für Werkstoffe, Wärmebehandlung, 

Fertigung - HTM, 58, 4/2003, p. 

189-197 

[4] Grabke, H. J. et al; Die Prozessregelung 

beim Gasaufkohlen und Einsatzhärten; 

expert verlag, Renningen-Malmsheim, 

1997, p. 65. K 

Fig. 10: Epsilon phase as a function of temperature [°C], nitriding potential [bar -0.5] (X-axis) 

and carburizing potential [bar] according to the Boudouard reaction (Y-axis) 

Dipl.-Ing. (FH) 


PROCESS-ELECTRONIC GmbH 

Heiningen (Germany) 

Tel.: 07161/ 94 888-0 

km.winter@ 

process-electronic.com 



Reports 

Reference measurements in gas 

carburizing atmospheres: part 

Džo Mikulovic´, Dragan Živanovic´, Florian Ehmeier 

The most important parameters for the control of carburizing processes 

are the temperature and the C-potential of the atmosphere. Temperature 

is normally measured by means of thermocouples. For the control of 

C-potential the measurement of oxygen partial pressure of the furnace 

atmosphere by in-situ O 2 -probes and Lambda probes (L-probes) became 

accepted. The thermocouples as well as the probes for measurement of 

residual oxygen gradually lose in accuracy. Therefore, reference measurements 

for adjustment of temperature and C-potential are essential 

for an exact control. In the first part of this article [1] the reasons for 

incorrect measurements with thermocouples and O 2 -probes, respectively 

L-probes have been explained. The appropriate reference measurements 

with calibrated thermo couple and gas analysis for correction of these 

faults were also described. Furthermore, it was explained what has to 

be observed with these reference measurements and which information 

is given, thereby, about the furnace atmosphere, especially with the gas 

analysis by means of a gas analyzer. Within part 2, following now, following 

additional reference measurements for C-potential will be presented: 

reference measurement with a second O 2 -probe or L-probe, dew point 

measurement and foil test. The advantages and disadvantages of theses 

reference measurements will be also discussed. 

The most important parameters for 

the control of the carburizing process 

are temperature and carbon potential 

(C-potential) of the atmosphere. 

To achieve accurate and reproducible 

results these parameters must be measured 

as accurately as possible. Due to 

aging and other possible sources of error 

the thermocouples and O 2 -probes as 

well as L-probes used for this purpose, 

over time, provide inaccurate or false 

readings [1]. Therefore, reference measurements 

are essential in order to correct 

the results accordingly. Otherwise 

there is no guarantee that by controlling 

the desired results will be achieved. 

As described in the first part of the article 

[1] the reference measurement for 

the temperature occurs via a test thermocouple. 

To determine the C-potential 

in the carburizing atmosphere several 

indirect and direct ways are available 

(Fig. 1). In carburizing atmospheres, 

using endothermic or nitrogen/methanol 

as carrier gas, CO and H 2 values 

are nearly constant. Therefore, in practice, 

to determine the C potential often 

only O 2 , CO 2 or the dew point is measured 

and the values for CO and H 2 are 

assumed to be constant. 

For controlling purposes the measurement 

of the oxygen partial pressure via 

O 2 -probe or L-probe has prevailed. The 

reference measurement via gas analysis 

Fig. 1: Determination 

of carbon 

potential in carburizing 

atmosphere 

(CO and CO 2 measurement via a gas 

analyzer) was described in part 1 of 

the article [1]. Below the indirect reference 

measurements of the C-level using 

a second O 2 -probe or L-probe and via 

dew point measurement are described. 

Advantages and disadvantages of some 

measurement methods for the direct 

determination of the C-potential are 

also discussed. 

Reference measurement of the 

C-potential with a second 

O 2 -probe or L-probe 

The construction and operating mode 

of the O 2 -probes as well as L-probes 

were described in detail in [2]. The reference 

measurement with these probes, 

as well as the reference measurement 

using CO and CO 2 gas analysis, has the 

advantage of allowing the measurement 

to be performed continuously. 

Using a C-potential controller which 

has the option to work with two probes 

and compare them, the failure probability 

of the C-potential control system can 

be reduced enormously. In this context 

we speak about redundancy. In technology 

this term commonly indicates 

the additional presence of functionally 

equal or comparable components of 

a technical system when they are not 


Reports 


have a different impact on the probes. 

In such case the failure of the probes 

can be viewed independently from each 

other which is very important regarding 

the calculation. Assuming that within 

a corresponding time period the first 

probe has a failure probability of 30 % 

P(probe1) = 0.3 and the second probe a 

failure probability of 20 % P(probe2) = 

0.2 the probability of both probes failing 

simultaneously is calculated as product 

of individual probabilities. The result of 

the considered case is as follows: 

Fig. 2: C-Potential controller Carbomat-M: a) Comparison of two parallel working probes; 

b) Setting menu for probe switching parameters 

needed in the normal case of a troublefree 

operation. 

The C-potential controller Carbomat- 

M holds the option to work with two 

probes in comparison (Fig. 2). One 

probe known as the leading probe is 

used for calculation of the C-level, the 

second probe works as comparison 

probe. In case of failure the Carbomat- 

M switches from the leading probe to 

the comparison probe and keeps calculating 

with the values of that probe. 

This avoids that the C-potential control 

and data recording will be interrupted 

especially if the probe fails during a current 

process. Murphys Law („Whatever 

can go wrong, will go wrong“ or for our 

purpose more appropriate formulation 

“If something can go wrong in different 

ways, it will always go wrong in the way 

which will cause the most damage”) [3] 

says that the failure of the probe will 

occur exactly at the time when the most 

damage can be caused. This damage 

can be prevented by using this redundant 

system. 

A short sample calculation will show how 

the failure probability of the C-potential 

control is reduced if a redundant system 

made of two parallel working probes is 

used. To eliminate systematic errors it is 

important to use probes of various types, 

e.g. an O 2 -probe and L-probe. Due to 

the fact that the probes are essentially 

different in construction the process 

and unit related interference influences 

P(probe1∩probe2) 

= P(probe1) . P(probe2) (1) 

= 0.3 . 0.2 = 0.06 

The failure probability for a system made 

of two probes is reduced to 6 % for the 

corresponding time period meaning an 

enormous reduction of the failure probability 

of the system. 

Reference measurement of 

C-potential by measuring of 

dew point 

For the determination of the C-potential 

from the H 2 O-content of furnace 

atmosphere the dew point is measured. 

The dew point or dew point temperature 

defines the temperature at which 

condensation of the water just starts. 

Fig. 3 shows the saturated vapour pressure 

line out of the phase diagram for 

water for the temperature range from 

-30 °C to +20 °C. The line which was 

determined experimentally represents 

the relationship between dew point 

and partial pressure and accordingly the 

proportion of water in an atmosphere. 

Knowing the dew point temperature of 

a furnace atmosphere, one can read the 

partial pressure from the diagram and 

thus determine the C-potential. In an 

atmosphere with a dew point of, e.g. 

+10 °C, the partial pressure of the water 

is 12.27 mbar. Using the Magnus formula 

[4], which for the first time was 

established in 1844 by Heinrich Gustav 

Magnus empirically and only supplemented 

by more accurate values since 

then, the partial pressure of water in a 

furnace atmosphere can be calculated 

from the dew point. For dew point temperatures 

≥ 0 °C the formula is 

(2) 

Fig. 3: Saturated vapor pressure curve for H 2 O 

 

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Reports 

and for dew point temperatures < 0 °C 

and > -65 °C 

(3) 

 

T is the dew point temperature in °C. 

The dew point sensors on the market 

with which the partial pressure of H 2 O 

can be determined continuously are not 

robust enough for the carburizing atmosphere 

and could not establish themselves. 

For dew point measuring the socalled 

mirror dew point measurement 

devices are used. The schematic design 

of these devices is shown in Fig. 4. The 

furnace gas is passed through a measuring 

chamber on the surface of a mirror. 

The mirror is cooled with a thermoelectric 

Peltier element until dew shows on 

the mirror surface. By use of a temperature 

sensor the temperature of the mirror 

surface can be detected. As soon as 

condensation starts the temperature of 

the mirror is read out directly. This is the 

dew point temperature. 

The mirror dew point checker Dewchecker 

1.1. (Fig. 5) is characterized 

mainly by the fact that the temperature 

of the mirror can be adjusted permanently 

to a constant value. For this purpose 

the required mirror temperature is 

defined as a fixed set point. The electronics 

then controls the Peltier element 

so that the predetermined set point 

temperature of the mirror is kept. This 

allows an accurate approximation to 

the dew point and thus a very accurate 

measurement of dew point independent 

of the operator. For an accurate 

dew point measurement with mirror 

dew point measurement devices the following 

points have to be observed: 

• The gas sampling fitting in this case 

plays an equally important role as 

for a gas analysis with a gas analyzer 

and therefore has to be constructed 

as described already in the first part 

of the article [1]. 

• If the dew point of the gas to be 

measured is higher than the ambient 

temperature or higher than any 

part of the sample gas extraction 

system, it will lead to premature condensation. 

This is particularly the case 

when the sample gas supply lines 

come in contact with cold parts (e.g. 

water pipes) or are placed near open 

Fig. 4: Schematic construction of a mirror dew point measuring system 

windows or on cold walls. Premature 

condensation in the measuring chamber 

system of the dew point measuring 

device can also occur when the 

device is brought from a cold to a 

warmer room and if the dew point 

of the gas to be measured is above 

the temperature of the device parts 

which are in contact with the gas. 

Remedy: 

If condensate has formed within the 

measuring gas extraction system the 

suction hose should be detached 

from the gas sampling point. Then air 

should be sucked through the device 

with the installed pump until pipes, 

filter and measuring chamber are dry 

again. The check whether the system 

is dry is assuaged when the dew 

point of the ambient air is measured 

before the measurements of the furnace 

atmosphere with the device are 

started. By occasional measurements 

of the ambient air dew point it can 

Fig. 5: Dewchecker 1.1 

(Prototype) 

be controlled if the dew point is still 

constant after the measurement and 

the measuring system has remained 

dry. 

• The devices should be maintained and 

calibrated regularly. For calibration of 

the entire measurement system different 

dew points are generated by 

use of a controlled climatic chamber. 

The measurement is then performed 

with the device to be calibrated and 

with a with a precision dew point 

hygrometer. From the comparison 

of the measured values then a corresponding 

correction is made so that 

the readings are within tolerance. 

Direct determination of the 

C-potential 

The methods for direct measurement 

of C-potential include measurements 

using pure iron wire and pure iron foil. 

In the measurement with pure iron wire, 


Reports 


Fig. 6: Foiltester FPG 1.0 with terminals T200 and T300 

the wire is exposed to the carburizing 

atmosphere to be determined. Then, 

with a resistance meter the resistance 

and by that the difference in resistance 

is measured. From the change in electrical 

resistance the C-potential of the 

atmosphere is determined. 

When measuring is done with an approx. 

0.05 mm thick pure iron foil, the foil is 

exposed for 10 to 15 min. to the furnace 

atmosphere to be determined. Due 

to the necessary balance the duration of 

measurement depends on temperature 

and C-potential of furnace atmosphere. 

Fig. 7: Accessories for foiltester FPG 1.0 

Subsequently, the carbon content of the 

foil is determined. For this there are various 

methods [4-6]: 

Glow discharge spectroscopy 

(GDOS): This is the most accurate 

method. With the GDOS it is possible 

to measure the depth profile of carbon 

in the foil. When using this method, so 

to speak, the carbon content in the core 

of the foil is used as a measure of the 

C-potential. All error conditions such as 

contamination or surface oxidation of 

the foil which would lead to errors in 

other methods of measurement do not 

matter in GDOS. Despite of the high 

accuracy this method is far too complicated 

and too expensive to determine 

only the carbon content in foils with it. 

Combustion process: The combustion 

process for determining the carbon 

content in foil is widespread today. The 

foil is heated in a small pot with about 

1 g of tungsten granulate. In a highfrequency 

furnace the material burns 

under pure oxygen. With suitable filters 

all oxides except carbon dioxide are 

filtered out. Then, the CO 2 content is 

measured with an IR absorption meter. 

The CO 2 content determined in this way 

is a measure for the carbon content of 

the foil or accordingly the C-potential 

of the furnace atmosphere. In comparison 

with eddy current measuring and 

weighing of the foil, this method is very 

expensive and time consuming. In addition, 

the calibration effort in this process 

is considerably high and requires a high 

skill of the operator. 

Eddy current method: With this method 

the differences in the electromagnetic 

properties of the foil caused by the different 

carbon content are analyzed by an 

eddy current measurement. The advantage 

in comparison to the foil weight 

measurement is that you do not have to 

deal with the foil carefully because dirt 

and impurities do not affect the result. 

Compared to weight measurement the 

eddy current measurement, however, 

has significant disadvantages. The electromagnetic 

properties analyzed here 

are not only depending on the carbon 

content of the foil, but also on other 

parameters, such as lattice structure and 

particle size. These parameters depend 

again on how quickly and how much 

the foil cools down. It is very difficult 

to eliminate these error sources in practice. 

Another major drawback is that for 

calibration of the instrument a second 

measurement procedure, usually foil 

combustion or weight measurement 

must be available. If one of those procedures 

is already used, however, it is 

uneconomical to purchase an additional 

device that has no significant advantages. 

Gravimetric method: Weighing with 

a precision scale is certainly the easiest 

and cheapest method for determining 

the carbon content in pure iron foils. 

The weight of the foil before and after it 

is exposed to the furnace atmosphere is 

measured. From these two weight measurements 

and the carbon content of 

282 



Reports 

the foil before it was exposed to the furnace 

atmosphere, the weight percentage 

of carbon is calculated as follows: 

 

(4) 

m 0 is the weight of the foil before it is 

exposed to the furnace atmosphere, m 

the weight of the foil after it is exposed 

to the furnace atmosphere and % C 0 

the basic carbon content before the foil 

is exposed to the furnace atmosphere. 

The weight fraction of carbon calculated 

with formula (4) corresponds to the 

C-potential of the furnace atmosphere 

according to DIN 17014. When the 

gravimetric method is used it has to be 

ensured that errors due to impurities in 

the form of soot, grease or fingerprints 

are avoided. In addition all forms of oxidation 

during removal of the foil have to 

be prevented, as oxide layers lead to a 

distortion of the result. 

Direct measurement of C-potential 

with foil tester type FPG 1.0 

The foil tester type FPG 1.0 (Fig. 6) is 

a precision scale for gravimetric determination 

of carbon content in thin iron 

foils. The weight is measured with a tension 

strip bedded moving coil mechanism. 

The C-potential can be measured 

with an accuracy of ± 0.01 % C. 

To ensure high measurement accuracy 

over a longer period of time the foil tester 

needs to be calibrated with a 95 mg 

test weight every time when it is turned 

on. The foils used for measurement have 

a weight of about 97 mg. This allows 

measurements at the calibration point 

which leads to high accuracy. Furthermore 

each measurement cycle performs 

seven measurements. The maximum 

and the minimum measured values are 

ignored and the average value is calculated 

out of the five remaining measurements. 

As already mentioned it is very important 

for an accurate weight measurement 

that the foil is free of contaminants such 

as grease or fingerprints. For that reason 

each foil tester contains miscellaneous 

accessories (Fig. 7), which are required 

to prepare the foils. The foil has to be 

wrapped around the attached wooden 

stick and afterwards inserted into a plastic 

bottle filled with acetone for cleaning. 

For measuring it has to be removed 

with anti-magnetic tweezers and dried 

Fig. 8: Software “T300 View” 

with a heat gun or hair dryer. The foil 

should not be touched with the hands 

thereafter. 

A special feature of the device is the 

easy manual operation with the terminals 

T200 or T300. The display of the 

operation terminals show each step in 

plain text and thus a correct handling 

of the device is ensured. With the 

operating terminal T300 and the corresponding 

PC software „T300 View“ 

(Fig. 8) usernames and names for the 

foil samples can be added and managed. 

With an USB flash drive all data 

can be transferred to a PC and analyzed 

and archived with the software. 

Foil sample and two-point 

correction 

The direct determination of the 

C-potential with a foil tester is often 

used to correct the C-potential, which is 

calculated with an O 2 -probe or L-probe. 

Most C-potential controllers allow an 

offset or in other words a correction of 

the C-potential in one operating point. 

This correction is adequate for processes 

with a constant C-potential and a constant 

temperature. For carburizing processes 

where temperature and C-potential 

are changed such corrections are not 

sufficient. 

Fig. 9: C-Potential controller Carbomat-M: a) Menu for C-potential correction with foil test; 

b) Menu with values for two point correction 


Reports 


The inaccuracy of O 2 -probe measurements 

is usually caused by fine hairline 

cracks in the ceramic of the probe. The 

extent of the cracks depends on the 

temperature. Therefore the measurement 

errors with the probe are different 

at various temperatures. If the C-potential 

is corrected at a high temperature, e. 

g. at 920 °C and a C-potential of 1.2 % 

C the measuring results with the probe 

and thus also the control near to these 

values are very accurate. If, however, 

the temperature and the C-potential are 

lowered the value becomes inaccurate 

because of the different behaviour of 

the probe and the correction made. 

With the C-potential controllers Carbomat-M 

(Fig. 9) and Carbo-M it is easy 

to achieve a correction in two points 

with the foil test. If the temperatures 

at which the corrections with the foil 

sample are made differ by more than 

30 °C the controllers handle these values 

as corrections in two different points. Otherwise 

the values of the first correction 

are overwritten with the values of the 

second correction. It is recommended to 

perform the foil sample at a carburizing 

temperature of about 920 °C and 

1.2 % C and at a hardening temperature 

of about 880 °C and 0.80 % C. The 

intermediate values are then automatically 

interpolated. This results in a very 

accurate C-potential measurement and 

control in the entire working range. 

Conclusion 

For quality assurance reference measurements 

are essential. In the process 

of gas carburizing the temperature and 

the C-potential are the key parameters 

that have to be monitored and reviewed 

regularly. The reference measurement 

of temperature is carried out in practice 

by an in-situ verification of the thermocouples, 

which means in the plant on 

site. For the C-potential there are several 

methods suitable as reference measurement. 

The presented method in the first part 

of the article, the gas analysis by NDIR 

sensors, is furthermore an additional 

tool for solving of various problems. The 

reference measurement with a second 

O 2 -probe or L-probe provides the advantage 

that with appropriate controllers 

the process can be controlled without 

any interruption with the second probe 

automatically if the first probe fails. The 

mirror dew point measurement instrument 

is not only suitable for C-potential 

reference measurement. With this 

device also the dew point of an endogas 

generator can be determined which 

can be used as reference measurement 

for the dew point control system of the 

generator. 

Among the methods used for direct 

determination of the C-potential in particular 

the gravimetric method has to be 

emphasized. The weight measurement 

with a foil scale is easy to perform and 

very economical. For these reasons the 

weight measurement is preferred in 

practice compared to the other direct 

methods. 

Literature 

[1] Džo Mikulović, Dragan Živanović, Florian 

Ehmeier: Carbon controlling with 

O 2 -probe and L-probe. HEAT PROCES- 

SING (7), issue 3, 2009, p. 231-236 

[2] Džo Mikulović, Dragan Živanović, Florian 

Ehmeier: Reference measurements in gas 

carburizingatmospheres: part 1. HEAT 

PROCESSING (8), issue 3, 2010, p. 237- 

244. 

[3] Arthur Bloch: Gesammelte Gründe, 

warum alles schiefgeht, was schief gehen 

kann!. Wilhelm Goldmann Verlag, 1985 

[4] Dietrich Sonntag: Important new Values 

of the Physical Constants of 1986, 

Vapour Pressure Formulations based 

on ITS-90, and Psychrometer Formulae. 

Z. Meteorol. 40 (1990), 5, S. 340-344 

[5] H. Klümper-Westkamp, P. Mayr, W. 

Reimche, K. L. Feiste, M. Bernhard und 

F.-W. Bach: Bestimmung des Kohlenstoffgehaltes 

in Aufkohlungsfolien. HTM 

57 (2002) 5, S. 364-372 

[6] Karsten Lothar Feiste, Karl-Michael Winter: 

C-Detect – Ein alternatives Verfahren 

zur Kohlenstoffbestimmung in Reineisenfolien 

zum Abgleich von Aufkohlungsatmosphären. 

GASWÄRME International 

(56) Nr. 5/2007, S. 359-362 

[7] Mac Roggatz, Norbert Engler: Praxisnahe 

C-Pegelüberprüfung der Ofenatmosphäre 

mittels Eisenfolien. GAS- 

WÄRME International (56) Nr. 5/2007, 

S. 366-369 

Dr. Džo Mikulovic´ 

MESA Electronic GmbH 

Geretsried (Germany) 

Tel.: +49 (0) 8171-76930 

dmikulovic@ 

mesa-international.de 

Dr. Dragan Živanović 


Niš (Serbien) 

Tel.: +49 (0) 8031/ 

900576760 

dzivanovic@ 

mesa-international.com 

Dipl.-Ing. (FH) 

Florian Ehmeier 


Geretsried (Germany) 

Tel.: +49 (0) 8171 / 76930 

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Subscription: Martina Grimm 

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284 



Basics 

Physical basics and industrial 

applications of heating processes 

Edition 16: High frequency heating 

Physical and technical basics as well as modern and innovative industrial 

applications of heating processes will be presented periodically here in 

the HEAT PROCESSING. The follow up continues in this issue with high 

frequency heating, a very fast, energy efficient and economical heating 

process, which is applied in particular for drying applications in many 

industrial branches. 

Physical and technical basics 

High frequency heating or so-called 

radio frequency (RF) heating is a form 

of dielectric heating, which is based on 

the physical principle of generating heat 

in polarisable materials with non or low 

electrical conductivity by the action of a 

high-frequency electric field [1,2]. 

The electric field is penetrating the 

material and due to the influence of the 

alternating field the orientation of existing 

electrical dipoles is changing continuously. 

This effect, so-called orientation 

polarization, takes place in materials 

with asymmetric molecular structure, 

like water molecules (Fig. 1). Due to 

the intermolecular friction the high frequency 

electrical energy is transformed 

to heat, which is generated in the material 

itself. But also free movable ions or 

atoms present in the material can be 

influenced by an alternating electrical 

field. This effect, so called ion and electron 

polarization or space charge polarization, 

leads to heat generation as well. 

As a result of the different molecular 

structures, not all materials are equally 

suited for the dielectric heating. The 

generated heat density in the material 

is amongst others proportional to the 

dielectric losses of the material and the 

frequency of the alternating field. Therefore 

the use of high frequencies results 

in a fast, effective heating. Heating in 

the electromagnetic radiation field using 

frequencies in the range of Giga-Hertz, 

e.g. 2.45 GHz, is called microwave heating 

[3]. The frequency range of radio 

frequency heating is between 0.3 and 

approximately 500 MHz, where the 

RF-heating takes place in the electrical 

field of a capacitor. Inside this frequency 

spectrum only some frequencies are 

allowed to use. The so called ISM (Industrial-Scientific-Medical) 

operating frequencies, 

which are almost solely used 

are 13.56 MHz ±0.05 %, 27.12 MHz 

±0.06 %, and 40.68 MHz ±0.05 %. 

The main prerequisite to apply successfully 

the RF-heating is, that the material 

to be heated has a sufficient high 

dielectric loss factor (e´r tand) greater 

than 0.02 (Table 1). In case of smaller 

factors, higher frequency is needed and 

therefore microwave heating is more 

effective. Due to its permanent polar 

molecule structure water has a comparably 

high dielectric loss factor of about 

0.36 for the frequency of 10 MHz. 

Therefore the RF-drying of containing 

water products is predestinated. 

Well appropriate to RF-heating are per 

example also rubber products and some 

plastics, but the dielectric loss factor is 

very different for plastic materials. For 

example PVC can be heated very good 

using the RF-heating, but PE and in particular 

PTFE (Teflon) are nearly transparent 

for the high frequency field without 

any absorption of energy. 

Technologies and installations 

Electrode systems, which are connected 

with a high frequency generator, are 

used in the RF-heating to transfer the 

energy into the product to be heated. 

The geometry of the electrodes should 

be adapted to the shape of the piece to 

be heated in order to realize the desired 

heat distribution. The most simple configuration 

of the electrodes is a plate 

Fig. 1: Polarization mechanism: a.) orientation polarization, b.) ion polarization, c.) electron 

polarization [2] 


Basics 


Table 1: Dielectric properties of typical materials to be heated by dielectric heating 

capacitor, where the product to be 

heated is between the plates as shown 

in Fig. 2. The electrodes can have also 

direct contact with the material in order 

to realize the necessary contact pressure, 

e.g. in case of gluing of wood plates or 

panels. A distance between the electrodes 

and the product to be heated is 

required, e.g. for continuously running 

processes. In this case the product can 

be transported with the help of a conveyor 

belt through the capacitor field. 

The continuously heating of flat products 

is possible using one side or double 

side stray field electrodes. The heating 

installations have an electromagnetic 

screening in order to avoid electromagnetic 

stray fields in the immediate vicinity. 

For the energy supply of RF-heating tube 

generators are normally used. The high 

frequency energy is guided via matching 

and control units to the product to 

be heated. The main advantages of tube 

generators are the realizable high power 

of about several hundred kilowatt, the 

sufficient high voltage at the outlet 

of the generator and the operational 

robustness of the tube. The generator 

efficiency of about 55 % to 65 % is a 

Fig. 2: Principle of high frequency heating [1] 

disadvantage of tube generators. High 

frequency generators on the basis of 

semiconductors are in further development 

and today they are still limited due 

to relatively small power. 

Process advantages and 

applications 

In comparison to the indirect heating 

methods, like e.g. convective heating, 

the RF-heating has numerous process 

advantages. If the electrodes are 

adequate designed the product will be 

heated in entire volume. This leads to 

approximately homogeneous temperature 

distribution in case of homogeneous 

material properties. This advantage has 

an important effect in case of products 

with low heat conductivity. Because 

water is heated around 100 times faster 

than typical nature or synthetic fibres, 

the drying of those containing water 

products, due to the selective heating 

of the moist zones of the material, takes 

place from the inner side to the surface 

without any overheating of the product 

itself. This results in a gentle heating 

with a high rate of drying and small specific 

energy demand in comparison with 

convective drying. The selective heating 

of containing water products leads to a 

self controlling effect during the drying 

process, because the energy absorption 

in already dried areas is very small and 

no overheating takes place. 

Because of the large electromagnetic 

wave length of about 11 m in the free 

space and a frequency of 27.12 MHz, 

the RF-heating is very suitable for the 

treatment of large-scale material strips 

und big volume products. Today the 

following fields of application are well 

established: 

• Drying and gluing of wood and cellulose 

products 

• Drying of textile and glass fibre as 

well as paper strips 

• Pre-heating and welding of plastics 

• Unfreezing and conservation of raw 

material and food. 

In case of wood drying during the process 

the temperature gradient from the 

core to the surface of the wood results 

in very short process times in comparison 

to the convection drying. The RF-heating 

is applied successfully for the drying 

of sawn wood, where mainly constant 

profiles thicker than 60 mm are dried 

continuously with a high throughput. In 

case of a throughput speed up to 4 m/s 

RF power up to 25 kW is applied. The 

drying process starting from a moisture 

content of 50 % and ending with a 

moisture content of 8 % has a process 

time of about 2 to 4 h. 

At the production of chipboards and 

fibreboards for the furniture and building 

construction industry the conventional 

used contact heating with oil or 

electric heated press plates can be substituted 

by pre-heating in the capacitor 

field and subsequent pressing. In this 

way the press capacity and the production 

time of the wood plates will 

be reduced considerable. The energy 

demand is depending on the thickness 

of wood plates between 150 up to 

200 kWh/m 3 of the chipboards, where 

high frequency power of up to 300 kW 

is applied. 

Also in the textile and leather industry 

the RF-heating with installed power 

between 25 and 300 kW is used for 

drying purposes. Especially in case of 

big volume products, like yarn coils and 

Fig. 3: RF-drying of yarn coils 

(Source Siemens AG) [2] 

286 



Basics 

bags of wool as well as washed and 

coloured dyed yarn coils, the principle 

physical based advantages of the dielectric 

heating in comparison to convective 

drying are significant (Fig. 3). In comparison 

to conventional drying in hot 

air heated drying chambers significant 

saving of energy costs, higher product 

quality and smaller floor space can be 

realized using high frequency installations. 

During the production of paper the 

homogeneous distribution of the moisture 

within the entire paper web is a significant 

quality criterion for the follow 

up production processes. These high 

level requirements on the moisture profile 

and the reached final moisture level 

can be reached successfully applying RFheating 

due to the selective drying and 

the small thermal inertia. The drying is 

carried out in RF-continuously running 

installations with width up to 12 m and 

through put velocities of the paper web 

up to 1.000 m/min. Depending on the 

grammage of the paper and on the drying 

rate, e.g. from 15 to 9 % content of 

moisture, installed power up to 900 kW 

is used. The RF-drying results in a homogeneous 

shrinking and therefore excellent 

flatness of the paper webs. This 

results in small rejections and improved 

printing quality of the paper. 

Up to now the big potential of application 

possibilities of the RF-heating is 

not completely used. Due to increasing 

requirements on the quality of the products 

as well as the permanent progress 

in economical and ecological improvements 

of the processes also in future 

new innovative fields of application of 

the RF-heating will be realized. 

Literature 

[1] Starck, A. v.; Mühlbauer, A.; Kramer, C.: 

Handbook of Thermoprocessing Technologies. 

Vulkan-Verlag, Essen 2005 

[2] Pfeiffer, H.: Pocket Manual of Heat 

Processing. Vulkan-Verlag, Essen, 2008 

[3] Baake, E.: Principles of Heating Processes. 

Edition 6: Microwave Heating. HEAT 

PROCESSING, Vol. 5, Issue 3, 2007, 

pp. 255-257 

K 


Egbert Baake 

Institute of Electrotechnology 

Leibniz University 

of Hannover (Germany) 

Tel.: +49 (0)511 / 762 3248 

baake@etp.uni-hannover.de 

KNOWLEDGE for the FUTURE 

Handbook of Burner Technology for Industrial Furnaces 

The demands made on the energy-efficiency and pollutant emissions of industrial furnaces are rising 

continuously and have high priority in view of the latest increases in energy prices and of the discussion 

of climate change for which CO2 emissions are at least partly responsible. Great importance is now 

attached to increasing energy-efficiency in a large range of industrial sectors, including the steel industry 

and companies operating heat-treatment installations. This work is intended to provide support for those 

persons responsible for the clean and efficient heating of industrial furnaces. 

The book discusses the present-day state of technological development in a practically orientated manner. The 

reader is provided with a detailed view of all relevant principles, terms and processes in industrial combustion 

technology, and thus with important aids for his or her daily work. This compact-format book, with its plethora 

of information, is an indispensable 

reference source for all persons who 

are professionally involved in any way 

at all with the heating and combustionsystems 

of industrial furnaces. 

Order now by fax: +49 / 201 / 820 02-34 or send in a letter 

Selected topics: 

Combustion theory, Fluid mechanics, 

Heat transfer, Combustion technology, 

Computer simulation, Pollutant 

reduction, Heat exchangers, Industrial 

burners (types and applications), 

Standards and legal requirements, 

Thermodynamic tables and terms, etc. 

Vulkan-Verlag 

www.vulkan-verlag.de 

Yes, please send me 

___ Cop. Handbook of Burner Technologiy 

for Industrial Furnaces 

Editors: A. Milani, J. Wünning 

2009, 218 pages, hardcover, 

€ 90.00, ISBN 978-3-8027-2950-8 

Vulkan Verlag GmbH 

Versandbuchhandlung 

Postfach 10 39 62 

45039 Essen 

Germany 


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Editors: Ambrogio Milani, Joachim Wünning 

2009, 218 pages, hardcover, € 90.00 

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Please note: According to German law this request may be withdrawn within 14 

days after order date in writing at Vulkan Verlag GmbH, Versandbuchhandlung, 

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✘ 

Date, Signature

HK 2011 

PRODUCTS AND SERVICES 

New Thgro-AX series with a range of new 

parameters 

Just in time for the 50 th anniversary 

of their power controllers, 

AEG PS has launched 

a new generation of thyristor 

power controllers that features 

a range of new parameters 

and sets new standards 

on the market. 

The new Thyro-AX series 

supports voltages of 24V to 

600V while offering a unique 

product range from 16A up 

to 1,500A, available as one, 

two and three-phase units. 

The connection technology 

of FlexConnect allows power 

controllers to be connected 

from either the top and/or 

the bottom. A premiere is celebrated 

by the full-graphics 

touch display, which is used 

for the first time in a power 

controller by a manufacturer 

and allows extremely intuitive 

handling. Thereby new 

opportunities are offered 

with regard to visualization 

and parameter settings. Set 

points and actual values as 

well as operating modes etc. 

are displayed in plaintext with 

operating modes also being 

indicated via changing backlights. 

In addition Ethernet as 

well as USB 2.0 interface 

are now included as a 

standard interface by 

which the power controller 

can be parameterized 

even when 

being disconnected. As 

an alternative browserbased 

option, parameter 

setting / visualization 

can also be made 

via an integrated web 

server. In the case of 

enabled communication 

and in combination 

with master control systems 

in the process and 

automation environment, 

traditional fieldbus 

protocols are available, 

e.g. DeviceNet, Modbus 

RTU, Profibus and CANOpen, 

as well as optional bus modules 

for TCP/IP based communication 

such as Profinet, 

Modbus TCP and Ethernet IP. 

Another characteristic feature 

of the new generation 

is its use of intelligent and 

advanced technologies for 

network interference reduction 

and mains load optimization 

to help reduce costs, 

energy consumption and CO 2 

emissions during operation. 

AEG Power Solutions GmbH 

www.aegps.com 

Foyer / Booth 10 

the machine tools in 

the manufacturing 

line can be achieved. 

To realize a OPF-heat 

treatment, a new process 

and equipment 

technology was developed, 

which is based 

on low pressure carburizing 

at high temperatures 

(HT-LPC) 

and subsequent high 

pressure gas quenching 

(HPGQ) which 

offers a dramatic 

reduction of process 

time. This is achieved 

by loading the gear 

components in a single-layer 

mode onto 

the workpiece carrier 

followed by a rapid 

radiation-heating up 

to carburizing temperature. 

After this 

high temperature carburizing 

takes place at temperatures 

up to 1,050 °C to achieve a 

good carbon absorption and 

an accelerated diffusion. This 

is followed by low distortion 

hardening in a dry gas 

flow as final process step. To 

achieve a typical case depth 

of 0.65 mm the process time 

is 40 min as compared to typically 

180 min which results 

in a process time reduction 

of more than 75 %. By the 

use of micro-alloyed case 

hardening steels, undesired 

grain growth during the high 

temperature process can be 

avoided. 

For the optimal application of 

the new process technology 

the SyncroTherm ® -module 

was developed. This module 

including peripherals has 

compact dimensions and can 

be integrated in the gear manufacturing 

line in-between 

the soft- and hardmachining. 

By loading the workpiece carrier 

with 20 gears, each with 

a diameter of 115 mm and a 

typical case hardening depth 

of 0.65 mm the cycle time is 

about 20 s. A prototype of 

this equipment is installed 

in ALD´s technical center in 

Hanau ready to heat treat 

customers parts. 

ALD Vacuum Technologies 

GmbH 

www.ald-vt.de 

Hall 9 / Booth 936 

Safe and efficient air cooling for endogas 

generators and quench oil tanks 

Heat treating module SyncroTherm ® allows fully 

integration of case hardening 

ALD Vacuum Technologies 

latest development is the 

heat treating module Syncro- 

Therm ® . This module allows 

the fully integration of case 

hardening of gear components 

and other parts into the 

One-Piece-Flow (OPF)-manufacturing. 

Thereby an optimum 

synchronization with 

Water cooling systems are 

considered the standard in 

wide areas of the heat treatment 

industry these days, 

however, there are some 

considerable disadvantages: 

not only are the running costs 

of the facilities increasing due 

to the rising water prices, but 

also the calcification of the 

pipes requires frequent attention 

and maintenance. Moreover, 

there is the danger of 

explosive evaporation of the 

water at high temperatures. 

Therefore, the Avion Europa 

GmbH & Co. KG, the exclusive 

distributor of the SBS 

288 



HK 2011 

corporation in Europe, 

presents two systems 

based on air cooling 

at the colloquium for 

heat treatment: Especially 

for endogasgenerators 

the End-O- 

Therm was developed, 

which ensures a high 

quality of the gas due 

to consistent cooling. 

The quench air cooler 

is applied at quench 

tanks with oil or polymeric-water 

solutions 

and provides for the 

required temperature 

control and for the 

homogeneity of the 

quenching material. 

In both systems the drop in 

temperature is achieved by 

one to two fans, the power 

and cooling capacity are 

adjusted to the specific need 

of the application. The coolers 

are designed in a very 

compact way and do not 

need any complex piping, 

which allows for a spacesaving 

integration into the 

manufacturing process. Since 

no water runs through the 

facility the use of expensive 

stainless steel tubing is not 

required. Moreover, it was 

made sure when designing 

the facility that the inner parts 

with the cooling unit are easily 

accessible in order to facilitate 

the cleaning process. The 

used ambient air is still clean 

after the cooling process and 

can simply be released into 

the environment. The heat 

contained in it could also be 

used for further purposes, for 

example, for space heating. 

Avion Europa GmbH & Co. KG 

www.avion-europa.de 


New self-recuperative burner for direct-fired 

furnace heating applications 

Eclipse, Inc. has introduced 

the TJSR v5 self-recuperative 

burner for direct-fired furnace 

heating applications. The 

advanced burner design combines 

a high velocity flame 

with fuel saving recuperation. 

A space saving integral eductor 

pulls the furnace exhaust 

through an internal ceramic 

recuperator. The recuperator 

preheats the incoming combustion 

air to very high levels, 

which improves furnace 

operating efficiency to reduce 

fuel usage by as much as 

50 % over typical ambient air 

burners. The TJSR v5 design 

eliminates the need for the 

hot air ductwork required by 

external recuperators, providing 

savings in hardware and 

installation. The internally 

insulated heat exchanger 

section and exhaust housing 

hold heat in the recu- 

HK 2011 Wiesbaden 

October 12–14, 2011 

Hall 1, Stand 132 

Thermal Processing Equipment 

for the Production of Bearings. 

Designed, Manufactured and Serviced 

by AFC-Holcroft. 

One of the most diverse product lines in the heat treat equipment industry: 

Pusher Furnaces, Continuous Belt Furnaces, Rotary Hearth Furnaces, 

Universal Batch Quench (UBQ) Furnaces – all designed and optimized 

for the production of bearings 

Customized solutions with full turnkey service including load/unload automation, 

press quenching, etc. 

Worldwide infrastructure in North America, Europe and Asia 

More than 90 years of experience and thousands of projects realized worldwide 

For further information please visit www.afc-holcroft.com 

AFC-Holcroft USA · Wixom, Michigan | AFC-Holcroft Europe · Boncourt, Switzerland | AFC-Holcroft Asia · Shanghai, China

HK 2011 


perative section, adding to 

the heat recovery efficiency. 

This also keeps external temperatures 

very low, providing 

better operator comfort and 

reduced thermal wear on 

associated equipment outside 

the furnace shell. The 

integrated gas and air orifices 

simplify burner piping, set-up 

and adjustment. There is no 

guesswork with input levels 

or burner capacit 

The new burner housing 

design is up to 40 % lighter, 

making furnace structural 

changes and installation simpler, 

with no fear of high 

stress mounting areas. Internal 

components are made 

of space age silicon 

carbide materials, 

built to deliver excellent 

heat transfer 

and extremely long 

burner life. Installation, 

operation, and 

maintenance are 

simplified and less 

costly. And the fuel 

savings are constant, 

with no degradation 

of the exchanger/ 

recuperator section, 

even after years of 

use. TJSR V5 can be 

fired on natural gas, propane 

or butane. The burner is available 

in three sizes, with a maximum 

capacity ranging from 

200,000 to 600,000 BTU/ 

hr. (60 to 175 kW). With the 

TJSR v5, you can light anywhere 

in the ignition range, 

with no pilot required. The 

TJSR v5 is capable of firing 

at High/Low/Off. On-ratio firing 

and excess air firing can 

also be accomplished. With 

the highest flame speed in 

the industry, TJSR v5 delivers 

a stable flame throughout its 

full input range. 

Eclipse, Inc. 

www.eclipsenet.com 


Widened range of corrosion inhibitors 

With the development of 

new corrosion inhibitors, 

BON Quenching Technology 

widened its product portfolio 

by the low-odor and very 

economical Dewatering Fluid 

SERVITOL 2404, the solvent 

free SERVITOL 4310 for the 

temporary and the SERVITOL 

4610 for the longtime protection 

against corrosion. Additional 

benefits offered by the 

said products are their minimum 

specific consumption 

and the fact that they meet 

the latest standards regarding 

health and safety of the 

workers and the protection of 

the environment. 

Development, manufacturing 

and sales comprise high 

performance quenching oils, 

polymer quenchants, corrosion 

inhibitors, cleaning 

agents and stop-off paints. 

Sales are accompanied by a 

free pre- and after-sales service 

including thorough consulting 

in order to optimize 

the heat treatment technology 

in question but also 

control and monitoring of 

the quenchants and cleaning 

media during use. 

BURGDORF GmbH & Co. KG 

www.burgdorf-kg.de 


Automatic gas burner control for one-stage 

burners with pilot burner or direct ignition 

Microprocessor-controlled 

automatic gas burner control 

for intermittent and continuous 

operation of one-stage 

atmospheric burners or 

fanned burners, in particular 

for industrial thermoprocessing 

equipment to EN 746-2. 

The program sequence and 

times can be customized by 

setting software parameters. 

Two independent flame 

detectors: ionization input, 

gate input. 

Extension module for Profibus/Modbus 

communication 

is available. Additional functions 

by extension modules 

are possible: Version MPA 

4111 (Plastic housing, IP 42) 

without display, MPA 4112 

(Plastic housing, IP 54) with 

integrated display, MPA 4122 

(Metal housing, IP 65, suitable 

for food industry (Regulation 

(EG) No. 1935/2004). Accessories 

are selectable: Flame 

detector, ignition transformers, 

parameterization and service 

box. 

Karl Dungs GmbH & Co. KG 

www.dungs.com 


Furnace technology for a number of different 

applications 

In principle, drum furnaces 

are indirectly heated. The process 

chamber of these plants 

consists of a heat-resistant 

metallic or ceramic tube. 

Energy is indirectly introduced 

in the product process 

from the outside through 

the tube wall. The indirect 

heating ensures separation 

between the atmosphere 

of the heating room and of 

the process chamber thus 

providing for an oxygen-free 

atmosphere for the product. 

Drum furnaces can optionally 

290 



HK 2011 

be heated using an electrical 

heating or a gas burner. 

ELINO has long-term experience 

and can offer various 

designs for the processes 

under ambient air atmosphere 

and for special gastight 

designs with process 

gases, e.g. argon, N 2 , H 2 , 

flammable gases or vapor. 

Rotary tube furnaces and 

rotary drum furnaces made 

by ELINO provides for a high 

technological standard and 

allow for very long lifetimes. 

Depending on the process 

conditions, heat treatments 

of up to 2,200 °C can be 

carried out. Product-specific 

various components can be 

integrated in the process 

chamber to allow for optimization 

of the thermal and 

chemical processes. On the 

basis of the single product 

transport, these plants meet 

the demands of many applications 

in the chemical and 

powder producing industry. 

ELINO provides a large number 

of plants for oxidizing 

and reducing atmosphere. 

Calcination, pre-reduction, 

and carburization of metal 

powder in the rotary drum 

furnace are delivered as complete 

systems, as desired. 

Pyrolysis, synthesis and gasification 

plants on the basis 

of ELINO drum furnaces are 

used in the field of alternative 

energies. On the basis 

of the process parameters 

determined in our pilot plant, 

ELINO can scale up the system 

for industrial plants. 

ELINO INDUSTRIE-OFENBAU 

GMBH 

www.elino.de 


Expanding of BIO/ZIO and BIC/ZIC burner 

ranges 

Elster Kromschröder has 

expanded its proven BIO/ZIO 

and BIC/ZIC burner ranges 

with the inclusion of insulation 

inside the housing for 

preheated combustion air. 

The new BIOW/ZIOW and 

BICW/ZICW burners can 

be used with hot air up to 

500 °C and make better use 

of their energy-saving potential, 

through increased preheating 

of the air. 

These new variants have a 

larger flanged air connection 

and are available for burner 

sizes 65 to 200. The timetested 

modular construction 

of the Kromschröder burners 

means that they can be 

adjusted in length to fit the 

furnace geometry. For the 

BICW and ZICW models, TSC 

ceramic tubes are available 

in all the usual dimensions. 

Thanks to the high outlet 

velocity, this combination is 

particularly suitable for intermittent 

operation. The BIOW/ 

ZIOW will be combined with a 

burner quarl which will allow 

a longer flame or a flat flame 

aligned against the furnace 

wall. Special versions are possible 

for applications at higher 

process temperatures. 

All burners feature direct spark 

ignition and are equipped 

with ionization flame control. 

Versions with integrated pilot 

ignition lances can also be 

supplied as an option and it 

is also possible to convert the 

burners for UV control using 

conversion kits. 

Elster GmbH, Kromschröder 

www.kromschroeder.com 


nanodac recorder with an optional dual 

programmer 

The nanodac device will soon 

be available with an optional 

dual programmer supporting 

up to 100 programs locally, 

each program supporting 25 

segments. This is a huge benefit 

with so many processes 

that often need to vary the 

set-point of the control process 

over a set period of time, 

by using a set-point program. 

New programmer functionality 

with crystal sharp display 

with easy to assess program 

status: 

• Using program names for 

easy identification 

• ‘Traffic Light’ status indication 

• Easy to read progress bars. 

Eurotherm Deutschland 

GmbH 

www.eurotherm.de 


New pyrometer provides higher accuracy in 

high-temperature environments 

The newest addition to Luma- 

Sense Technologies’ line of 

temperature-measurement 

devices is a digital-ratio, twocolor 

pyrometer that allows 

industrial manufacturers to 

improve product quality and 

yield by more-accurately measuring 

extreme temperatures 

in the harshest environments. 

The ISR 6 advanced is a noncontact 

pyrometer that gives 

operators greater control over 

their processes and is wellsuited 

for the steel and metals, 

silicon, glass and cement 

manufacturing industries. The 

sensor is applicable for temperature 

ranges between 600 

to 3,000 °C. This makes the 

device suitable for applications 

that require precise temperature 

measurement at very 

high temperatures such as 

induction heating, annealing, 

welding, forging, melting, 

sintering, or growing crystals. 

Other key features that make 

the ISR 6 Advanced one of 

the most accurate pyrometers 

of its kind include a small 

spot size down to 0.7 mm, 

a response time of less 

than 2 ms and a two-color 

method that uses adjacent 

wavelengths for temperature 

determination. In contrast to 

a conventional pyrometer, 


HK 2011 


HybridCarb system significantly 

raises efficiency, from 

2 % to up to 30 %. The gas 

amount used in the process 

is cut by a factor of ten. This 

means that yearly gas consumption 

per furnace can be 

reduced from about 65 t to 

about 7 t, resulting in yearly 

savings of up to € 25,000 per 

furnace. 

Ipsen International GmbH 

www.ipsen.de 


Protective gas chamber furnaces with vacuum 

the ISR 6 Advanced’s temperature 

measurement is largely 

independent of an object’s 

emissivity and is unaffected 

by dust and other contaminants 

in the field of view. 

It also improves production 

quality by reducing the risk 

of false test results with its 

ability to automatically detect 

low signals. If needed, the 

pyrometer can be switched to 

1-color mode and used like a 

conventional pyrometer. 

LumaSense Technologies Inc. 

www.lumasenseinc.com 


With gastight muffle for heat 

treatment processes under 

protective gas atmosphere up 

to 1,050 °C. Useful chamber 

25 to 480 l and according to 

customer specification. 

For soldering and annealing 

of workpieces, scalingfree 

treatment of sensitive steel 

• Inconel muffle for a maximum 

operating temperature 

up to 1,200 °C 

• 3-zone-control 

• gas feeding device, burning-off 

device and flame 

supervision 

• safety package 

• gas circulation 

HybridCarb cuts gas carburization process-gas 

costs by a factor of ten 

A carburization process using 

natural gas usually looks like 

a meeting of pyromaniacs: a 

blazing, flickering fire at both 

ends of the case-hardening 

furnace. The entire amount of 

natural gas, about 16 m 3 /h, 

remains in the oven for a 

short period of time only and 

then burns up in a controlled 

process. About 97 % of the 

gas burns off unused. 

Ipsen International GmbH has 

now developed a method 

to radically improve the efficiency 

of this process. Hybrid- 

Carb, Ipsen‘s new process 

gas converter, recycles almost 

all the gas from the oven 

through a processing chamber 

instead of just flaring it 

off. The gas mix is enriched 

using Ipsen’s patented hybrid 

process and fed back into the 

oven. 

The entire process can be 

easily controlled with the 

Ipsen system control set. The 

qualities, debinding and sintering 

of workpieces, oxidation 

or reduction of surfaces 

and many more applications, 

under protective gas atmosphere. 

A huge selection of 

options enables universal 

application: 

• rapid cooling 

• gas re-cooling 

• vacuum up to 10 -5 mbar at 

up to 1,000 °C. 

Linn High Therm GmbH 

www.linn.de 


New technology of Catalytic Gas Nitriding 

(CGN) 

For European extruders 

«Nakal» represents electric 

furnaces for thermo-chemical 

treatment, especially developed 

for nitriding of extrusion 

dies and die steels to improve 

quality, reduce costs and 

increase heat treating speed 

of these parts. 

The main advantage of nitriding 

furnaces is a new technology 

of Catalytic Gas Nitriding 

(CGN) which has a patent in 

Russia as well as in Germany, 

Canada and USA. 

CGN technology is a multipurpose, 

simple and proven 

in practice method of low 

temperature thermo-chemical 

treatment for machine and 

tools components, providing 

improved and stabilized oper- 

292 



HK 2011 

Universal batch quench chamber furnace 

available in three sizes 

ating abilities of treated parts 

as well as lower manufacturing 

costs. Nitriding process 

control is provided automatically 

by NPCS (Nitriding Process 

Control System) which 

doesn’t require humans to be 

involved in the process. The 

usage of CGN technology in 

nitriding furnaces allows to: 

• Minimum twice reduce the 

process time, 

• Improve new quality of the 

nitrided case, 

• Greatly increase treated 

parts service life. 

JSC Nakal 

www.nakal.ru 


AFC-Holcroft will be featuring 

their UBQ (Universal Batch 

Quench) chamber furnace. 

The UBQ comes in three standard 

sizes (gross load capacity 

of 500 kg, 1,600 kg or 

2,750 kg) - and custom sizes 

are also possible. 

The UBQ is one of the most 

versatile furnaces in the industry, 

able to perform metallurgical 

processes such as neutral 

hardening, carburizing, 

carbonitriding, normalizing, 

annealing and ferritic nitrocarburizing 

(FNC). AFC-Holcroft’s 

UBQ offers the option 

of an atmosphere cooling 

chamber, in addition to their 

integral oil quench systems. 

A full range of companion 

pieces offer maximum flexibility 

– accessories include stationary 

and scissor lift tables, 

tempering furnaces, spray/ 

dunk washers and transfer 

cars. AFC-Holcroft’s UBQ furnace 

has demonstrated an 

precise degree of accuracy 

and consistency. The UBQ furnace 

guarantees temperature 

uniformity of +/- 5 °C. However, 

recent tests with a 1,370 

x 1830 x 915 mm load at 

carburizing temperatures 

(900 °C range) have demonstrated 

uniformity within 

less than +/- 3 °C. Even more 

impressive are results of less 

than +/-4 °C at FNC temperatures 

(570 °C range). 

The metallurgical achievements 

realized by the UBQ 

have led to the development 

of the UBQA, designed specifically 

for austempering and 

martempering, using water 

or polymer quench. Using 

molten salt in an integral 

quench system, the UBQA is 

capable of neutral hardening, 

carburizing, carbonitriding, 


HK 2011 


carbo austempering, normalizing, 

annealing, austempering 

steel, and austempering 

ductile irons (ADI). The UBQA 

can through harden up to a 

6” thick cross section using 

the patented water injection 

system to provide the necessary 

quench severity. 

Another enhancement to the 

UBQ is AFC-Holcroft’s UBQI 

– developed for the growing 

IntensiQuench market. The 

UBQI utilizes a rapid and uniform 

cooling of steel parts to 

cause the formation of martensite 

through the whole 

part surface. The resulting 

hard shell of martensite is 

characterized by finer structure 

with improved mechanical 

properties, such as minimizing 

distortion and increasing 

overall strength. 

AFC-Holcroft 

www.afc-holcroft.com 


These systems are mostly 

equipped with mechanical 

rotary vane pumps and 

roots pumps for martensitic 

hardening of components 

of different steel qualities. 

The generated fine vacuum 

atmosphere realizes the typical 

bright surface aspect heat 

treatment result. Vacuum 

equipment used for brazing 

with nickel based filler metal 

in high vacuum atmosphere 

has usually installed an additional 

oil diffusion pump. 

In many specialized areas constantly 

increasing demands 

on materials and their wide 

range of specific heat treatment 

and joining processes 

have correspondingly higher, 

differentiated demands on 

the furnace technology. 

A basic requirement for the 

furnace atmosphere during 

annealing processes such as 

special alloys or titanium brazing 

of diamond materials in 

10 -6 mbar range is offered 

with all-metal vacuum chamber 

furnaces. The furnace 

heating chamber is insulated 

with multi layer molybdenum 

and stainless steel layers, 

instead of graphite material. 

Amongst others, dry running 

mechanical backing pumps 

as well as turbo molecular 

pumps or cryo-pumps are 

used for evacuation to the 

lowest required high-vacuum 

ranges. 

For many decades SCHMETZ 

GmbH offers tailor-made vacuum 

furnace configuration 

for vacuum thermal processes 

of small components to heavy 

weight production batches. 

Schmetz GmbH 

www.schmetz.de 


Heat treatment equipment designed for highest 

availability 

Vacuum furnaces with molybdenum hot zone 

The most common applications 

of a 1 chamber-type 

furnace are annealing, hardening, 

tempering and brazing 

of components of different 

types of steel materials. 

In general, water-cooled 

1 chamber-type furnaces 

with graphite felt insulated 

heating chamber accomplishment 

with rectangular or 

round versions are used for 

these or similar tasks. 

Schwartz GmbH supplies 

continuous and batch-type 

heat treatment furnaces 

operating in air or controlled 

atmospheres as required. 

Advanced heating systems 

ing is also gaining widespread 

acceptance in the automotive 

industry. 

Schwartz heat treatment 

furnaces satisfy customers’ 

meet exacting demands in 

terms of environmental protection 

and energy savings. 

Various types of Schwartz 

furnaces are used for following 

applications: Hardening, 

tempering, heat treatment, 

normalizing, soft and bright 

annealing. Hot form harden- 

needs to increase the strength 

of safety-critical components 

while at the same time saving 

weight and cost. In this field, 

Schwartz GmbH has established 

itself as a key partner 

to a number of renowned 

automotive manufacturers, 

evolving into the leading sup- 

294 



HK 2011 

plier of heat treatment equipment 

for hot form hardening 

applications. The range of 

furnaces currently in service 

comprises various options, 

i.e.: with and/or without part 

carriers; with gas, electric or 

hybrid heating system; with 

and/or without protective 

atmosphere. 

Schwartz GmbH 

www.schwartz-wba.de 


tive and cost-effective solution 

for businesses that work 

with many different metals, 

and have had, until now, to 

maintain multiple analyzers. 

Because the SPECTROLAB can 

be configured to analyze all 

ten common base materials, 

the instrument covers all daily 

instrument requirements, 

making a second instrument 

superfluous. 

Spectro Analytical Instruments 

GmbH 

www.spectro.com 


High-end spectrometer with hybrid optic offers 

precision in metal analysis 

SPECTRO Analytical Instruments 

unveiled the updated 

version of its SPECTROLAB 

metal analyzer. The latest 

version of the versatile metal 

analyzer incorporates a number 

of improvements, and, 

in several instances, achieves 

better detection limits than 

tion. With the complexity of 

spectra, this was long considered 

impossible, because 

the number and selection of 

lines was limited by the positioning 

of the PMT detectors. 

With the new SPECTROLAB 

analyzer, the entire spectrum 

from 120 to 780 nm now is 

Universal batch furnace for low pressure 

carburizing 

SECO/WARWICK is introducing 

a new line of equipment, 

the CaseMaster Evolution 

universal batch furnace for 

low pressure carburizing 

equipped with an oil or gas 

quench. These systems provide 

a technically advanced 

alternative to traditional 

integral quench furnace systems 

for many applications 

including: aviation, automotive, 

machine tool, bearings, 

commercial heat treating. 

This single system is 

capable of performing low 

pressure carburizing (LPC by 

FineCarb ® ), LPC with pretion 

software. The CaseMaster 

Evolution system offers 

many process advantages: 

no CO 2 emissions, vacuum 

10 -2 mbar, (10 -5 option), 

nominal temperature up to 

1,320 °C, ±5 °C in the heating 

chamber, optimal processing 

gas consumption, 

charge transport to the oil in 

less 20 s and many more. 

The SimCarb module is 

available to design and simulate 

carburizing processes 

prior to running trials. By modeling 

processes in advance, 

process parameters can be 

its predecessor version, e.g. 

trace analysis of pure copper 

and aluminum. 

Optimized excitation parameters 

and an innovative readout 

system enable permanent 

enhancements for lead analyzis 

with a focus on battery 

technology or in the analyzis 

of precious metals, for example. 

Even during automotive 

and aerospace materials testing, 

the new SPECTROLAB 

analyzer displays its unique 

strengths. The new SPEC- 

TROLAB analyzer is able to 

analyze aluminum, magnesium 

and titanium alloys with 

a single hardware configura- 

available to users. 

In redesigning the SPECTRO- 

LAB stationary metal analyzer, 

SPECTRO placed special 

emphasis on ease of operation 

and reduced operating costs. 

With those considerations in 

mind, SPECTRO placed components 

that could require 

maintenance in easily accessible 

locations. An extended 

diagnosis and log file system 

also assist users in monitoring 

the instrument’s status 

and in performing accurate 

trouble shooting, helping to 

lengthen maintenance intervals 

and shorten repair times. 

SPECTROLAB also is an attrac- 

nitriding (PreNitLPC ® ), bright 

hardening (oxidation in preheat 

chamber), annealing 

and tempering. PreNitLPC ® 

is a new technology that 

provides process integrity at 

higher temperatures, saving 

process costs by reducing the 

carburizing cycle. The LPC 

systems is supported with the 

proprietary SimVac simulachecked, 

saving process 

time and avoiding scrapped 

parts. The furnace operation 

will meet AMS 2750D, 

AMS 2759, BAC 5621, PN-EN 

98/37 and PN-EN 746-1 standards. 

SECO/WARWICK 

www.secowarwick.com 



HK 2011 


Highly precise temperature and oxygen 

measurement technology 

For almost 30 years thermocontrol 

Körtvélyessy GmbH 

has been manufacturing 

highly precise and durable 

thermo elements and oxygen 

probes. The innovative design 

features enable the well 

known precision and reliability 

of the products. Some of 

the features are: 

ence air supplies for oxygen 

probes 

• the enabling of a temperature 

measurement in 

dynamic magnetic fields 

with a patented system of 

thermowires. 

With the company’s successful 

ISO 9001:2008 certifica- 

offers an optimal alternative 

to chromed components. Neither 

the coating process nor 

the subsequent disposal of 

components is harmful to the 

environment. 

The thermo-chemical IONIT 

OX process is a combination 

of gas nitrocarburizing, 

plasma activation, and oxidation. 

The layer structure consists 

primary of an iron-nitride 

tapped by an anti-corrosive 

iron-oxide Fe 3 O 4 and can be 

individually tailored. This combination 

provides high surface 

hardness up to 1100HV 

including lower friction, and 

increased tool lifetime compared 

to chromium coatings 

– especially of dynamically 

loaded components. These 

excellent properties allow 

even selecting cheaper materials 

driving additional costsavings. 

In this case the substitution 

of expensive materials 

is possible, for example of 

stainless steels. 

Sulzer Metaplas GmbH 

www.sulzermetco.com 


New ammonia sensor in gas analysis unit 

MGas 5.1 NH 3 

• the avoidance of drifteffects 

due to the use 

of different thermowire 

diameters in all thermocouples 

• the chance of in-situ calibration 

measurements of 

thermoelements via separate 

build-in empty tube 

• the enabling of flexible 

mounting positions of oxygen 

probes due to a fully 

ceramic design 

• no need of external refertion, 

the PARTS product line 

has been launched. It deals 

with manufacturing and 

sales of OEM-products, such 

as thermocouples in ceramic 

protection tubes, mineral 

insulated thermocouples and 

different plugs for the OEM 

and resale market. 

thermo-control Körtvélyessy 

GmbH 

www.thermo-control.com 


As a result of permanent 

improvement and optimization 

measures the company 

MESA Electronic GmbH presents 

the enhancement of the 

gas component ammonia in 

their new gas analysis unit 

MGas 5.1. The measurement 

principle of the newly developed 

NH 3 sensor is based on 

a tunable diode laser (TDSL), 

which measures and redeems 

the absorption of ammonia 

(NH 3 ) and water. The current 

measurement capacity covers 

the range of 0…20000 ppm 

ammonia. The measuring 

camber of the analyzer is 

Combi treatment IONIT OX for the hydraulic 

industry 

Hydraulic components are 

used versatile. Special requirements 

are corrosion protection 

in different atmospheres 

protection against contact 

corrosion with other metals. 

The patented plasma combi 

treatment IONIT OX from 

Sulzer Metaplas offers the 

perfect solution. The protective 

oxide layer generated in 

this process provides an excellent 

protection in aggressive 

medias, like oils, lubricants, 

bio fuels and saltwater. Additionally 

the passivity of the 

treated surface prevents contact 

corrosion with other metals 

– also with light and nonferrous 

alloys. This environmentally 

sustainable process 

heated up to 120 °C. The 

analyzer is often used in the 

carbo nitriding process. 

The gas analyzis unit MGas 

5.1 NH 3 will store all measurement 

data in an internal 

memory. The user is able to 

transfer the data via USB stick 

to the supplied software. 

Optional interfaces are available 

as in RS485, Modbus, 

Ethernet and other interfaces. 


www.mesa-international.de 


296 



HK 2011 

Advanced radiant tube technology 

Ever increasing demand in 

regard to metallurgical properties 

makes it necessary 

to heat-treat metal components. 

Many heat treatment 

processes – especially at high 

temperature – cannot take 

place in air but require a pro- 

The high energy-efficient 

combination of recirculation 

radiant tubes and self recuperative 

burners represent 

the state of the art for indirect 

heating systems. Based on 

many years of experience in 

manufacturing of high grade 

of high performance materials, 

as well as new manufacturing 

methods at UCON’s 

facility makes the products 

more efficient than before. 

Modern recirculation radiant 

tubes are available as single 

ended version (SE), P- or double-P 

version. Conventional 

U- or W- shapes are produced 

according to the same system. 

Further features of these radiant 

tubes are: A high resistance 

to mechanical impact 

which might occur during 

handling, installation or may 

be caused by parts falling 

down; tubes can be repaired, 

thus reducing the maintenance 

costs; small series or 

single-item production are 

available at short notice; typical 

applications are furnaces 

for steel heat treatment such 

as hardening furnaces, hot 

forming equipment, continuous 

annealing or galvanizing 

lines (CAL, CGL) as well as 

enameling furnaces. 

UCON Containersysteme KG 

www.ucon.de 


Gradient cooling 

tective atmosphere. In such a 

case, an indirect heating system 

is then mandatory. 

The standard heating equipment 

is usually composed of 

a burner and a radiant tube. 

wrought alloy process components, 

UCON have developed 

a new generation of 

radiant tubes. The enhanced 

mechanical strength provides 

for an extended application 

range. A new design, the use 

Both in our vacuum- and 

conveyer-belt furnaces this 

cooling is possible. The heat 

treated materials are best 

handled for certain applications. 

Even bainite is possible. 

Cooling gas mass flows from 

almost 0 up to the required 

maximum amounts per kg 

of heat treated material can 

be adjusted by the gradient. 

Heating, cooling, heating and 

cooling with nominal variables 

allow heat treatment 

programs, which were not 

possible in gas atmospheres 

up to now. 

WMU GmbH 

www.wmu-gmbh.de 



WIESBADEN 

12. – 14. Oct. 2011 



KNOWLEDGE 

for the 

FUTURE

Profile 

COMPANIES PROFILE 

ELINO INDUSTRIE-OFENBAU GMBH 

Company name/ ELINO INDUSTRIE-OFENBAU GMBH 

location: Düren (Germany) 

Board of 

management: 

History: 

Group: 

Dipl.-Ing. Dieter Schäufler 

Since 1933, ELINO INDUSTRIE-OFENBAU 

GMBH, as a competent plant construction 

firm, has been producing individual thermal 

treatment plants according to the customer’s 

specifications as well as standard plants of 

adapted sizes and performances. 

So, the traditional enterprise located in 

Düren, was decisively involved in the development 

of the powder metallurgy in Germany 

and its neighbouring countries and 

until today, it has been being one of the 

leading manufacturers of process plants for 

the hard-metal and refractory metal industry. 

In 2010, the ELINO INDUSTRIE-OFENBAU 

GMBH became a partner of the PLC Holding. 

Together with its subsidiaries WISTRA 

and ELMETHERM, we are now able to offer a 

wider product range delivered by a group of 

highly-specialized enterprises with a worldwide 

service and international production 

facilities. 

Number of staff: ELINO employs approx. 120 employees 

Product range: 

More than 4,000 delivered plants worldwide, 

customized high-tech systems, quality, 

reliability, flexibility, and innovative product 

development make ELINO INDUSTRIE-OFEN- 

BAU GMBH an ideal engineering partner for 

a wide variety of thermal treatment plants. 

The rotary furnace systems, developed in our 

house, are accepted worldwide and are used 

in various industrial branches, e.g. metallurgy, 

chemistry, nano-technology, disposal 

technology or recycling. The product range 

of the ELINO INDUSTRIE-OFENBAU GMBH 

includes industrial furnace plants with individual 

charging and straight-through-type 

furnaces with continuous feeding. ELINO 

Production: 

Competitive 

advantages: 

Certification: 

Worldwide service work, as well as modern- 

ization of existing plants are running by 

experienced and qualified staff. 

Expert advice and training on site round up 

the service. 

Service 

potentials: 

Internet address: www.elino.de 

Contact: 

INDUSTRIE-OFENBAU GMBH sets standards 

in the field of atmosphere control in continuous 

furnace plants. 

In complete thermal treatment systems, the 

furnaces are supplemented with plants for 

gas generation, gas treatment, and afterburning, 

as well as various feeding and 

transport systems. 

ELINO INDUSTRIE-OFENBAU GMBH manufactures 

furnace plants for treatment processes 

within temperature ranges of up to 

2,200 °C at continuous temperature; under 

highly pure, aggressive, toxic, vacuum or 

normal atmospheres; for product sizes in 

the nano range and up to several tonnes, 

and it ranges from laboratory furnaces to the 

complete production plant. 

ELINO INDUSTRIE-OFENBAU GMBH designs, 

engineers and manufactures equipment in 

their own company. 

An excellently equipped technical centre 

makes it possible to validate processes in a 

pre-industrial scale and with this, to define 

decisive parameters before the implementation 

of the desired processes in an industrial 

scale. A number of new production methods 

and products was only enabled by the technical 

centre of ELINO INDUSTRIE-OFENBAU 

GMBH in cooperation with the customer. 

The company is certificated to 

DIN EN ISO 9001; 

AEO DE AEOC 103 308. 

Petra Erdorf 

+49 (0)2421-6902-0 

info@elino.de 

298 


HEAT 

PROCESSING 

INTERNATIONAL MAGAZINE FOR INDUSTRIAL FURNACES · HEAT TREATMENT PLANTS · EQUIPMENT 

Business Directory 

I. Furnaces and plants for industrial 

heat treatment processes ............................................................................... 300 

II. Components, equipment, production 

and auxiliary materials .................................................................................... 309 

III. Consulting, design, service and 

engineering ....................................................................................................... 317 

IV. Trade associations, institutes, 

universities, organisations .............................................................................. 318 

V. Exhibition organizers, training and education .............................................. 319 

Contact: 

Mrs Bettina Schwarzer-Hahn 

Tel.: +49 (0)201 / 82002-24 

Fax: +49 (0)201 / 82002-40 

E-mail: b.schwarzer-hahn@vulkan-verlag.de 


Source: Aichelin Ges.m.b.H.

Bu s i n e s s Directory 

I. Furnaces and plants for industrial heat treatment processes 

Thermal production 

Melting, Pouring, Casting 

300 HEAT PROCESSING · (9) · ISSUE 3 · 2011



Heating 

Powder metallurgy 

HEAT PROCESSING · (9) · ISSUE 3 · 2011 

301



Heating 




Heat treatment 

More information available: 



303










305




Cooling and Quenching 




Cleaning and drying 

Surface treatment 

Joining 




307



Joining 

Recycling 

Energy efficiency 



II. Components, equipment, production and auxiliary materials 

Quenching equipment 

Fittings 

Burners 

Transport equipment 




309



Burners 




Burner applications 

Burner equipment 


311



Burner equipment 

Hardening accessories 

Resistance heating elements 

Inductors 




Gases 

Measuring and automation 


313



Measuring and automation 

Power supply 




Refractories 

Cleaning and drying 

equipment 




315



Refractories 


WIESBADEN 

12. – 14. Oct. 2011 



316 HEAT PROCESSING · (9) · ISSUE 3 · 2011 

KNOWLEDGE 

for the 

FUTURE


III. Consulting, design, service and engineering 




317


III. Consulting, design, service and engineering 

IV. Trade associations, institutes, universities, organisations 



V. Exhibition organizers, training and education 

Hotline 

Managing Editor: 

Editorial Office: 

Editor: 

Advertising Sales: 

Subscription: 

Dipl.-Ing. Stephan Schalm 

Annamaria Frömgen, M.A. 

Silvija Subasic, M.A. 

Bettina Schwarzer-Hahn 

Martina Grimm 

+49 201 82002-12 

+49 201 82002-91 

+49 201 82002-15 

+49 201 82002-24 

+49 931 41704-13 

s.schalm@vulkan-verlag.de 

a.froemgen@vulkan-verlag.de 

s.subasic@vulkan-verlag.de 

b.schwarzer-hahn@vulkan-verlag.de 

mgrimm@datam-services.de 


319

KNOWLEDGE for the FUTURE 

Handbook of Burner 

Technology for 

Industrial Furnaces 

The demands made on the energy-efficiency and pollutant emissions 

of industrial furnaces are rising continuously and have high 

priority in view of the latest increases in energy prices and of the 

discussion of climate change for which CO2 emissions are at least 

partly responsible. Great importance is now attached to increasing 

energy-efficiency in a large range of industrial sectors, including 

the steel industry and companies operating heat-treatment installations. 

This work is intended to provide support for those persons responsible 

for the clean and efficient heating of industrial furnaces. 

The book discusses the present-day state of technological development 

in a practically orientated manner. The reader is provided with a detailed 

view of all relevant principles, terms and processes in industrial 

combustion technology, and thus with important aids for his or her daily 

work. This compact-format book, with its plethora of information, is an 

indispensable reference source for all persons who are professionally 

involved in any way at all with the heating and combustion-systems of 

industrial furnaces. 

Selected topics: 

Combustion theory, Fluid mechanics, Heat transfer, Combustion technology, 

Computer simulation, Pollutant reduction, Heat exchangers, Industrial 

burners (types and applications), Standards and legal requirements, 

Thermodynamic tables and terms, etc. 



ISBN 978-3-8027-2950-8 

HEAT PROCESSING is published by Vulkan-Verlag GmbH, Huyssenallee 52-56, 45128 Essen, Germany 

Order now by fax: +49 (0)931 / 4170-492 or send in a letter 

Vulkan-Verlag 

www.vulkan-verlag.de 

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___ Cop. Handbook of Burner Technologiy for Industrial Furnaces 



ISBN 978-3-8027-2950-8 

Vulkan Verlag GmbH 

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First name, Surname of recipient (department or person) 


Country Postcode Town 

Phone 

E-Mail 


✘ 

Date, Signature 

Fax

Index of Advertisers 

Page 

AFC-Holcroft Europe, Boncourt, Switzerland ...................................................................................................... 289 

AICHELIN Ges.m.b.H., Mödling, Austria ................................................................................................ Back Cover 

ALD Vacuum Technologies GmbH, Hanau, Germany ......................................................................................... 229 

aluexpo 2011, Istanbul, Turkey ............................................................................................................................ 278 

ALUMINIUM INDIA 2011, Mumbai, India ............................................................................................................. 239 

FABTECH 2011, Chicago, IL, USA ...................................................................................................................... 241 

INDUCTOHEAT Europe GmbH, Reichenbach/Fils, Germany ............................................................................. 262 

JSC NAKAL Industrial Furnaces, Solnechnogorsk, Moscow Region, Russia ..................................................... 293 

LOI Thermprocess GmbH, Essen, Germany .......................................................................................... Front Cover 

Oerlikon Leybold Vacuum GmbH, Köln, Germany .............................................................................................. 225 

Process-Electronic GmbH, Heiningen, Germany ................................................................................................ 275 

M.E.SCHUPP Industriekeramik GmbH & Co. KG, Aachen, Germany ................................................................. 227 

SECO/WARWICK ThermAL S.A., Swiebodzin, Poland ....................................................................................... 231 

SMS Elotherm GmbH, Remscheid, Germany .............................................................................. Inside Front Cover 

UNI-GERÄTE GMBH, Weeze, Germany .............................................................................................................. 221 

Wire / Tube Southeast ASIA 2011, Bangkok, Thailand ....................................................................................... 235 

Business Directory ....................................................................................................................................... 299-319 

Volume 9 · Issue 3 · August 2011 

Official Publication 

CECOF – European Committee of Industrial Furnace and Heating Equipment Associations 

Editors 

H. Berger, AICHELIN Ges.m.b.H., Mödling 

Prof. Dr.-Ing. A. von Starck, Appointed Professor for Electric Heating at RWTH Aachen, 

Dr. H. Stumpp, Chairman of the Association for Thermal Process and Waste Treatment 

Technology within VDMA, President of the LOI Group and Chairman of the executive 

board LOI Thermprocess GmbH, Essen, Chairman of the Exhibitors Council for MESSE 

THERMPROCESS 2011 

Advisory Board 

Dr. H. Altena, Aichelin Ges.m.b.H., Prof. Dr.-Ing. E. Baake, Institute for Electrothermal 

Processes, Leibniz University of Hanover, Dr.-Ing. H.-G. Bittner, LOI Thermprocess GmbH, 

Prof. Y. Blinov, St. Petersburg State Electrotechnical University “Leti“, Russia, Mike Debier, 

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HEAT PROCESSING High frequency heating (Vorschau)

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