Svetsaren nr 3. 2000 - Esab

A WELDING REVIEW PUBLISHED BY ESAB VOL. 55 NO.3 2000Automotive &Transport

A welding review published by ESAB AB, Sweden No. 3, 2000Articles in Svetsaren may be reproduced without permission but withan acknowledgement to ESAB.PublisherBertil PekkariEditorLennart LundbergEditorial committeeKlas Weman, Lars-Göran Eriksson, Johnny Sundin, Johan Elvander, Sten Wallin,Bob Bitzky, Stan Ferree, Ben Altemühl, Manfred Funccius, Dave MeyerAddressESAB AB, Box 8004, SE-402 77 Göteborg, SwedenInternet addresshttp://www.esab.comE-mail: info@esab.sePrinted in Sweden by Geson Skandiatryckeriet, KungsbackaAutomotive and transport.Photo: Ingmar Jernberg, Bildbyråni Göteborg.Contents Vol. 54 No. 3 20003Welding LPG tankers the ESAB wayA complete package of ESAB consumablescontributes to the successful fabrication ofLPG tanks at the Gdynia Yard in Poland.20ESAB pulsed gas-shielded metal arcbrazing of surface-coated sheetsGMA-brazing with ESAB Aristo 2000 andOK Autrod 19.30 gives the best quality andexcellent mechanical quality values.8FILARC PZ6015R – The robot friendlycored wire (III)Focus on ESAB’s aim to work closely withclients on mechanisation projects to sharpentheir competitive edge.24The use of rutile cored wires for weldinghigh strength steel in crane fabricationOK Tubrod 15.09 rutile cored wire helpsimprove the allover welding productivity atDutch crane fabricator Huisman-Itrec.12ESAB’s submerged arc solution forefficient trailer beam fabricationReplacing old double headed single wireSAW installation with a new submergedarc welding system helps Metal Design andFabrication, MDF, to meet increasingdemand for their products.28The new ESAB EcoMig welding wireadopted by Fai Komatsu Industries forwelding its earth-moving equipmentAn ecological product like ESAB EcoMighelps FKI, as one of the first metalmechanicalcompanies in Italy, with theapplication for ISO 14000.14Newly-developed consumable makesthin-plate welding more effectiveThe new metal-cored wire OK Tubrod14.11 can cut cycle times and help streamliningthe robot welding of thin plate.33Welding hydraulic cylinders usingOK Tubrod 14.11 and the MAG andMAG-tandem processHigh welding speeds with MAG weldingand increased productivity with the MAGtandem method using OK Tubrod 14.11metal-cored wire.17Stubends & SpatterShort news2 • Svetsaren nr 3 • 2000

Welding LPG tankers the ESAB wayby Ben Altemühl, editor of Svetsaren, interviewing Stocznia Gdynia production managementESAB is supplying the Gdynia Yard with a complete consumables packagefor welding gas tanks in NV 2-4 low-temperature steel.AcknowledgementWe would like to thank the Gdynia production managementfor allowing us to visit the yard and for providingus with the information on which to base this article.We would especially like to thank Mr. Zenon Szymanski(EWE*) and Mr. Marek Piechulski (EWE), thewelding engineers, for their co-operation and support.We also compliment our colleagues at ESAB Poland onthe marketing success achieved at the Gdynia yard.(*European Welding Engineer)Stocznia GdyniaVisiting this immense shipyard, located in the Baltic portof Gdynia, and witnessing the enormous activity, the titleof the national anthem automatically springs to mind,“Jeszcze Polska nie zgine,≥a”– “Still Poland is not lost”.The history of the Gdynia shipyard, founded in 1922,is associated in many ways with the 20th century miseryand uprising of the Polish nation as a whole. It was establsihedin the roaring twenties with ship repairs andwas as hard hit as Poland itself by the Great Depressionthat was soon to follow, smothering any attempt to transformitself into a fully-fledged new building yard. Itwould take a series of bankruptcies and re-starts undernew ownership before, at the end of the thirties, the firstGdynia-designed ships slid off the slipway.The rapid growth of the Gdynia shipyard was dramaticallyhampered by the outbreak of World War II. StoczniaGdynia was placed under the management of DeutscheWerke Kiel AG and was once again transformed into abusy repair yard and submarine building centre.In 1943 and 1944, allied bombing destroyed theshipyard almost completely. After Gdynia’s liberationby the Soviet and Polish Armies in 1945, the yard renderedall kinds of services, before it reached its presentform. Its portfolio of orders included chimney pipes fora portable stove and the repair of cars (among themthose powered by wood gas).The shipyard went on to become the largest repairbase for the Polish fleet when merchant and naval vesselsstarted coming back to Poland from their war-timewandering, along with the German ships given to Polandas war reparation and the English and AmericanSvetsaren nr 3 • 2000 • 3

Figure 1. Blueprint of a DNV class 1A1 LPG tanker.ships received from military stores. In the fifties and sixties,the majority of the ships that were built were deliveredto USSR owners. Soon after, a new era dawnedwhen the series production of B-523 type cargo shipswas started, fulfilling the special requirements of Norwegianowners. From that time, Stocznia Gdynia hadaccess to its own design department and more andmore orders were also received from western countries.From the mid-sixties, Gdynia has broken records designingand delivering up to 117,000 tonne deadweightOBO carriers, liquid gas carriers with prismatic tanks,bulk carriers and bulk tankers. In 1970, shipyard workersin Gdynia, just like their colleagues in Gdansk,undertook, on behalf of the whole nation, a rebellionagainst the government. A monument still serves as areminder of the victims who were killed and injured.In 1980, the powerful Solidarity movement wasborn in the neighbouring Lenin Shipyard in Gdansk,triggering martial law in 1981 but also political and socialchanges, which led to today’s market economy.Stocznia Gdynia is now one of the largest and mostprofitable European yards, exporting close to 100% of itsproducts to clients from all over the world. It is capableof building ships up to 400,000 dwt and consumes around150,000 tonnes of steel a year. It builds fishing trawlers,general cargo and multi-purpose container vessels, crudeand chemical tankers, OBO carriers, car carriers andlarge passenger ferries. The yard is ISO 9001 certifiedand has access to modern design and analysis tools suchas CAD/CAM, NAPA, Tribon and Foran systems.LPG carriersAt the time of our visit, the construction of the first oftwo 50,000 tonne deadweight DNV class 1A1 LPGtankers was nearing completion. These ships have fourtank sections with a total capacity of 78,500 m 3 , each ofwhich consists of two independent prismatic tanks (seeFigures 1 and 2). The tanks have a double hull and aresurrounded by a safety barrier. The red lines in Figure 2indicate the use of DNV class NV 2-4 low-temperaturesteel for the tanks and the safety barrier, whereas thegreen lines represent standard shipbuilding grades accordingto the Polish Bureau of Shipping (A32 andD32). The tanks are designed for a service temperatureof –50ºC at an overpressure of 0.275 bar. The CVN requirementfor the steel and the welds is 27J at –55ºC.Table 1 shows the chemical and mechanical requirementsfor DNV NV 2-4. Plates according to NV 2-4 specification are purchased from the Polish steel manufacturerHuta Czestochowa in three thickness categories;12, 20 and 28 mm.As can be seen from Figure 3, the carriers are constructedin sections according to modern shipbuildingpractice involving panel fabrication, the construction ofsub-sections, the assembly of grand sections and the finalconnection of grand sections in the dock. Platescoloured red represent DNV NV2-4 steel and the greenones indicate standard shipbuilding steel. The hull sectionsare welded together in the dock to form the hullof the ship. The tanks are completed at the yard beforebeing lowered into the hull. After this, the prefabricatedtop side including the deck is attached, together withthe processing installations (Figure 4).The welding of DNV NV 2-4 lowtemperaturesteelAlthough steels according to DNV class NV2-4 are developedfor low-temperature service, they contain onlya small amount of alloying elements and have a relativelylow carbon equivalent. In the thickness rangeused by the Gdynia Yard (12, 20 and 28 mm) to constructthe tanks, no preheating is required. However, toavoid the loss of HAZ impact toughness, there are limitationsto the heat input and the interpass temperature.From the point of view of the weld metal, extra careis required to avoid the loss of low-temperature impacttoughness. The consumables used by the Gdynia YardFigure 2. Crosssectionof an LPGtank consisting oftwo independentcompartments. Thered lines are DNVNV 2-4 class steeland the green linesare standard shipbuildingquality.4 • Svetsaren nr 3 • 2000

Figure 3. Exploded view of the tanker, showing constructionstages.for welding DNV NV 2-4 steel fall into two categories;basic for SAW and MMA and rutile Ti-B micro-alloyedfor FCAW.Basic consumables produce a low-oxygen ferriticweld metal, consisting mainly of large amounts of somewhatsoft grain boundary ferrite and acicular ferrite.The low-temperature toughness depends on the qualityof the soft grain boundary ferrite in the microstructureand is further improved by 2.5% Ni-alloying. The microstructureand toughness can be spoilt in two ways.When the heat input is too low, bainite or martensitemay appear as a result of the overly rapid cooling of theweld. When it is too high, the ferrite becomes coarse.For rutile, Ti-B micro-alloyed flux-cored wires, lowtemperaturetoughness is based on the presence oflarge amounts of fine acicular ferrite. In line with basicconsumables, the micro-structure is spoilt when bainiteor martensite is introduced when the heat input is toolow (see Figure 5). With high heat inputs, however,Figure 4. LPG carrier about half way through the productionprocess. On the left-hand side, the top side of the carrierhas been attached. On the right, the tanks (covered withinsulation material) are still visible.Figure 5. CCT diagram of CMn-Ti-B weld metal.grain boundary ferrite appears at the expense of acicularferrite, with an even more detrimental effect on thetoughness.When it comes to the welding of DNV NV 2-4, thismeans that the heat input has to be within a certainrange to be assured of the correct weld microstructure.ESAB recommends a heat input range of 1 to 2.5kJ/mmfor the consumables described under the next heading“welding consumables”. The welding techniques thatare used to build up the joint differ from normal shipbuildingpractice and are more in the direction of weldingfor offshore fabrication. Although preheating is notrequired for DNV NV 2-4 (as with many offshore steelgrades), the interpass temperature must be limited. Fullweaving, a very common shipbuilding technique, shouldbe avoided as much as possible because it can take theheat input beyond critical levels. The split-weave orstringer bead technique, both offshore fabricationmethods, may be less productive, but it ensures the correctweld microstructure with corresponding good lowtemperatureimpact values.ESAB has been involved in many LPG projects asa supplier of welding consumables and equipment. Inmany cases, the company has provided the welder withtraining and assistance in setting up suitable weldingprocedures. It has often proved necessary to instructwelders in the right techniques to obtain the desiredlow-temperature weld metal impact toughness. Specialsupport was given to Gdynia to get it started with thecored-wire welding of the LPG tanks of the carrierscurrently under construction.Welding consumablesTo construct the tankers, an innumerable number ofpanels have to be fabricated, to be connected to subsectionsand grand sections and finally to arrive at the%C %Si %Mn %S %P %N CE (C+Mn/10)

dock assembly of grand sections. Various welding processesare applied. Wherever possible, mechanisedwelding is used for increased welding productivity, butmanual welding is obviously indispensable for fit-upwork and the connection of sub- and grand sections, aswell as in dock assembly. Three welding processes prevail;MMA, SAW and FCAW. For the LPG tanks inDNV NV 2-4 steel and the hybrid connections betweenthe tanks and the normal ship quality steel hull, theESAB consumables listed in Table 2 are used.OK 73.68 is a basic, 2.5Ni-alloyed LMA electrodewith a recovery of 120%. It provides good impacttoughness, even in the vertical-up position.FILARC PZ6116S is a rutile, all-positional coredwire with Ti-B micro-alloying (+1.5%Ni) for use in CO 2shielding gas.OK Flux 10.62 is a high basic agglomerated flux(basicity index 3.4), suitable for single and multi-runwelding in both butt and fillet welds. It has excellentslag detachability and smooth side-wall blending. Incombination with OK Autrod 12.32 (DIN: S3), it producesgood CVN impact properties down to –60ºC.The typical all-weld metal chemical compositionand mechanical properties are shown in Table 3.Fabrication weldingTwo main SAW applications can be found in the fabricationof panels. Figure 6 shows the attachment of profilesusing double-sided tandem welding with the SAWFigure 9.FCAW underCO 2 gasprotectionwithPZ6116S.Figure 10.OutdoorFCAW withPZ6116S.Figure 11. LPGtank underconstruction.Figure 6. DoublesidedSAW weldingwith OK Autrod12.32/OK Flux 10.62.Figure 7. Single-sidedSAW welding withOK Autrod 12.32/OKFlux 10.62.Figure 8. MMA weldingwith OK 73.68.combination OK Autrod 12.32/OK Flux 10.62. Figure 7shows the same wire/flux combination used with a tractorfor shorter weld lengths.Another important SAW application is the connectionof plates to panel walls with butt welds usingdouble-sided welding. Figure 12 gives a characteristicwelding procedure specification. Note the maximuminterpass temperature of 150ºC, which is stipulated forall welding of DNV NV 2-4.MMA is applied to a limited extent only, mainly forfit-up work in the construction of the sub- and grandsections of the LPG tanks. Figure 8 shows MMA weldingwith OK 73.68, a very versatile consumable for thiskind of work.FCAW is being used increasingly to replace MMAin order to produce increased welding productivity, especiallyin positional welding. It provides a fine sprayarc at all applicable welding currents, making it easy tocontrol the heat input in vertical-up welding and thewelding of root passes on ceramic backing strips, for example.It is used indoors for manual fit-up work (Figure9), as well as outside in the fabrication of sub-sections(Figure 10) and the connection of tank segments tocomplete tanks, where it is used for the main vertical assemblywelds. The use of CO 2 shielding gas makes thewire more suitable for work outside in windy conditionsthan types using Ar-based mixed gas. Figure 13 shows a6 • Svetsaren nr 3 • 2000

For MMA OK 73.68 EN 499: E 46 6 2Ni B 32 H5 AWS A5.5: E8018-C1For FCAW PZ6116S EN 785: T 46 6 1.5Ni P C 1 H5 AWS A5.29: E81T1-K2 JFor SAWOK Flux 10.62/OK Autrod 12.32EN 756: S 46 6 FB S3SiTable 2. ESAB welding consumables for DNV NV 2-4.%C %Mn %Si %Ni Rm Re A5 CVN/–60ºC(MPa) (MPa) (%) (J)OK 73.68 0.05 1.0 0.35 2.4 610 520 26 105PZ6116S 0.05 1.3 0.4 1.5 615 550 25 75OK Autrod 12.32/OK Flux 10.62 0.07 1.4 0.3 – 580 475 28 90Table 3. All-weld metal chemical composition and mechanical properties of ESAB consumables for DNV NV 2-4.welding procedure specification for welding DNV NV2-4 in the PF position.ConclusionESAB is supplying the Gdynia Yard with a completepackage of consumables for welding LPG tanks inDNV NV 2-4 low-temperature steel. The package includesconsumables for MMA, SAW and FCAW.ESAB’s assistance with educating the welders and theestablishment of welding procedures, in particular forFCAW, has contributed to the successful fabrication ofthe tanks.Figure 12. Figure 13.Svetsaren nr 3 • 2000 • 7

FILARC PZ6105RThe robot-friendly cored wireby Tapio Huhtala, ESAB B.V., the NetherlandsIn Svetsaren 98/3 and 00/1, we introduced PZ6105R, ESAB’s metalcoredwire for robotic welding, and described its use for the fabrication ofexcavator frames in medium to thick steel, as well as the fabrication ofthin-plate automotive components.This article focuses on ESAB’s aim to work closely with clients on differentprojects involving mechanisation in our desire to sharpen their competitiveedge. Some additional applications will be presented in the field of thinplatewelding, including new applications from the automotive industry.The markets nowadays are becoming increasingly largeand transparent. This tendency offers commercial potentialto individual fabricators, but at the same time itcan entail a threat. Established companies are experiencingincreasing competition from newcomers in theirbranch of industry operating at international level. Inorder to remain competitive, they have to re-assesstheir business and change their market approach. Theyfrequently conclude that a new growth strategy is impededby what are known as limiting factors whichaffect the way they run their company.These limiting factors may be encountered in thesupply of raw materials, the availability of labour, productioncapacity, warehouse capacity, financing, marketdemand and the delivery of finished products to endusers. A bottleneck in one or more of these links in theproduction and marketing chain may account for thedifference between success and failure for the wholecompany.A shortage of skilled labour, for example, is a problemmany fabricators are coping with in today’s boomingeconomy. Being successful calls for a creative approachwhen it comes to recruiting new staff, reeducatingone’s own personnel, mechanisation, or evenoutsourcing work to specialist firms.The same goes for stocks. The market demand mayjustify a higher stock level, but at the same time companiesare trying to minimise the amount of money investedin stocks. Creative solutions are found in modernstock management systems such as EOQ (EconomicOrder Quantity), JIT (Just In Time) and MRP (MaterialsRequirement Planning).In the area of financing, renting or leasing can beconsidered when traditional financing instruments representa limiting factor.Welding, a necessary production step for many fabricators,can also constitute a bottleneck in the productionchain. This bottleneck can be concentrated at the weldingstation itself, but it is very often a combination offabrication steps associated with welding, such as highrepair and scrap rates.Co-operation with fabricatorsESAB makes its knowledge of welded fabricationavailable to the automotive industry by participatingin projects that aim to increase the competitiveness ofindividual fabricators in this field. In the assessmentof the welding situation and the implementation ofmore productive solutions, always in close cooperationwith the fabricator, different types of problememerge.One that is more or less standard is the lack of timeon the part of the fabricator who is often caught up in avery tight production schedule. Further down the line,there may be preoccupations about running tests onproduction lines at the risk of causing unacceptabledowntime. Very often, the availability of a skilled robotprogrammer is a problem that stands in the way of effectivetesting on the customer’s site.ESAB has recognised these problems and has developedits own test facilities to minimise on-site testingas far as possible and thereby the impact on thefabricator’s normal production set-up. When on-sitetesting becomes necessary, the type that has the least effectis chosen, for example, by utilising the weekends orother times when regular production is stopped.This working process is explained in more detailbelow.8 • Svetsaren nr 3 • 2000

Working processPhase 1In every case, the projects begin with a thorough evaluationof the production situation by skilled people fromESAB working together with the fabricator. Subjectssuch as needs, requirements, determination of bottlenecks,limitations related to welding equipment andtorch positions, discussions about present problems andso on are covered.When there is agreement that there are significantbenefits to be gained, the project proceeds into phasetwo.This consists of welding trials at one of our weldingapplication laboratories on samples supplied by the clients.Phase 2At the present time, ESAB has two locations (Utrechtin the Netherlands and Göteborg in Sweden) wheremore advanced tests including robot welding can becarried out. During the tests, the fabricator’s situation iscopied as closely as possible. If, for example, the freedomis given to test other gases, this is done to seewhether any additional benefits can be obtained. Quitefrequently, clients have a central gas network supplyinga specific shielding gas, so a change of shielding gas isthen out of the question.After the welding trials, the resultsare carefully evaluated and reported back to theclients. Assistance with cost calculations can also beprovided in cases where sufficient information has beenreceived.When the results of the welding trials show forsome reason that no additional benefits will be gainedby implementing the findings, the project is terminated.When the outcome is positive, it is up to the fabricatorto decide if and when he wants to move into phasethree, on-site testing. The major benefit provided byESAB by working in this way is, quite naturally, a minimumimpact on the company’s own production. Theonly risk the fabricator takes is the cost of the samplessent to the welding application laboratories.obtained, are made. The time span of the on-site testingvaries. Sometimes a short on-site test is followed by along-term one. After a careful evaluation of the datathat are obtained, it is up to the company to decidewhether or not to transfer its process.Some examples are given below of projects carriedout using this approach. As many fabricators, especiallyin the automotive industry, are not keen on publishinginformation about their production, we refrain frommentioning the names of the companies involved.Moreover, all the data presented here are values obtainedafter phase two in the different projects, i.e. aftertests at our welding application laboratory in Utrecht.Application 1Welding a safety component for trucksThe problem definition:• Lack of fusion caused by the torch being directedmore towards the inner ring. The reason for thistorch position is to avoid melting the outside edge ofthe sample• The spatter level is too high, resulting in an undesirableamount of post-weld grinding• The productivity of the welding station is too low, i.e.it is a bottleneck in the production processFigure 1 shows a cross-section of a safety componentfor trucks. The parent material is equal to St 37.2with an outer diameter of 100mm and a thickness of4.5mm. These parts have been welded with SG2-typesolid wire, diameter 1.2mm, using the pulse techniqueand a welding speed of 14.5 mm/s.Like all the other tests described below, the applicationresearch was performed with an ABB IRB 1400welding robot and an ESAB Aristorob 500 powersource. Suitable parameters for welding the circularweld were found at 398A/6V/10m/min. at 25mm stickoutlength. The travel speed obtained was 1.3m/min. Agas mixture of 90Ar/10CO 2 was used as gas protection.Phase 3During phase three, welding trials are performed onsite under ESAB’s guidance using the company’s ownequipment and new evaluations, based on the valuesFigure 2. Safety componentwelded with PZ6105RFigure 3. Etched crosssectionFigure 1. Safety componentFigure 4. Scaffolding componentSvetsaren nr 3 • 2000 • 9

Figures 5,6,7. Solid wire welds1,2,3Figures 8,9,10. Welds 1,2,3made with PZ6105R.Figure 11. Etchedcross-section A-Aof a scaffoldingcomponent weldedwith PZ6105R.The results showed a 38% increase in welding speedand the samples were free from spatter. The burn-inprofile and bead profile were good without any meltingof outer edges, suggesting significant potential for aproductivity increase as a result of a reduced scrap andrepair rate.Figure 2 shows the component after being weldedwith PZ6105R using the above-mentioned parameters.Figure 3 shows a cross-section of the weld. It can beseen that the weld is relatively flat with good penetration,without melting the outer edge, in a series of testsrepeatedly meeting all the quality objectives set by theclient.Application 2Welding scaffoldingThe problem definition:• Excessive spatter level necessitating post-weld cleaning• The productivity of the welding station is too low, i.e.it is a bottleneck in productionA non-automotive, yet interesting, application, involvingthe welding of 2.2mm thick tubes to produce scaffolding.The client uses robot welding together with1.0mm diameter solid wire under 80/20 Ar/CO 2 gasprotection, using conventional MIG power sources.Figure 4 shows a reference sample taken from theclient’s production. The numbers indicate the differenttypes of weld, whereas the letters show the locationsfrom which transverse cross-sections were taken fromsamples produced with PZ6105R. Figures 5 to 7 showthe solid-wire welds corresponding to the numbers 1 to3 in Figure 4.The same welds, now performed with PZ6105R usingthe same shielding gas, are shown in Figures 8 to 10.The welds are flatter and spatter is virtually absent. Atransverse cross-section taken from location A and representativeof the type of penetration obtained is shownin Figure 11.The results showed that the spatter could be almosteliminated. There is potential for increasing productivityby more than 40% and a corresponding cost reduction/sample of more than 20%.Figures 12a, b and c show the results of tests performedon another scaffolding component from thesame customer. The problem definition is the same asfor the previously mentioned component.Equally good results were obtained in terms ofspatter. The productivity increase and reduction in productioncosts were even larger than the abovementionedfigures.Figures 12a,12b,12c. Anothercomponent (12a) welded withsolid wire (12b) and withPZ6105R (12c).10 • Svetsaren nr 3 • 2000

Figures 13,14. Tow eyelet weldedwith solid wire and special fixture (14)for robotic tests with PZ6105R.Figure 15. Cross section of weld B infigure 14.Figure 16. Exhaust pipe hookApplication 3Welding tow eyelets and hooks for exhaustpipesProblem definition:• Productivity at the welding station is too low• The welding station is a bottleneck in the productionprocessThe third example deals with the welding of toweyelets with a plate thickness of 2mm (Figure 13). Thesteel bar which has to be attached has a diameter of12mm. Oil residue is frequently present on the 2mmplate.This work is currently done at a robot station with1.2mm diameter solid wire under 90Ar/7.5CO 2 /2.5O 2 ,using conventional MIG power sources. The welding isdone in the PB position at a travel speed of 0.8–1.0m/min.To perform the tests, a fixture was constructed forthe components (Figure 14). The letters indicate the locationsof the different welds. Figure 15 shows a transversecross-section of weld B. It is clear that the weldquality is good. Suitable parameters were found around290A/23V/8 m/min. at a travel speed of approximately1.62 m/min. for welds A to C (20mm stickout), accountingfor an increase in travel speed of around 70%.In combination with the above-mentioned application,another welding trial was conducted on hooks forexhaust pipe systems (Figure 16). This component isproduced at another robot station. It was not as urgentfor the customer to increase productivity at this stationas it was in the previous application. These tests wereconducted for future needs. The welding was done inthe PB and PG positions. Currently, solid wire 1.2mmis used under 90Ar/7.5CO 2 /2.5O 2 shielding gas. Thewelding speed for the major long weld deposited in thePG position is 1.2 m/min.Welding speeds in the range of 1.4–2.0.m/min wereachieved. The higher welding speed is valid for the longweld deposited in the PG position.SummaryThe competition within industry is increasing, forcingcompanies to re-assess their business situation. Identifyinglimiting factors has become increasingly important.There are some problems that companies have todeal with when working with process improvements.They include lack of time, limited access to robots andprogrammers and the risk of lost production associatedwith running on-site tests during normal productiontime. ESAB has recognised these problems and workstogether with a number of clients in a flexible manner,offering minimised risk levels and increasing the probabilityof success for clients.For more information, please contact your localESAB organisation.About the authorTapio Huhtala is a product manager for unalloyed coredwires at ESAB B.V. in Utrecht in the Netherlands. Hejoined ESAB in 1993 and worked as a research metallurgistin Goteborg until 1998.Svetsaren nr 3 • 2000 • 11

ESAB’s submerged arc solution forefficient trailer beam fabricationby Shaun Studholme and Derek Harvey – ESAB UK Ltd.Metal Design and Fabrication, MDF,a trailer beam fabricator located inAntrim, Northern Ireland has obtained amajor increase in manufacturing outputby installing a custom made ESAB twinwire submerged arc welding systemusing OK Tubrod 14.00S metal coredwire with OK 10.71 agglomerated flux.Figure 1. MDF’s custom made ESAB twin wire submergedarc welding system. At the request of MDF, part of thephotograph has been blurred.MDFMDF is a successful fabricator of trailer beams supplyingframes to the major truck manufacturers in the UKas well as several countries on the European mainlandand are expanding rapidly.To enable them to meet the increasing demand fortheir products, they decided to invest in a new submergedarc welding system for the fabrication of theirmainstream beams (figure 1), replacing their old doubleheaded single wire SAW installation using solid wire.ESAB were awarded the contract after having presenteda solution that provided increased welding productivityas well as flexibility for the various designs ofbeams that MDF produce. Along with the installationof the new system, MDF reorganised their workshoplayout to optimise the efficient supply of beam componentsto the welding station. Having used the new weldingunit for over a year, MDF claim that it is 3 to 4 timesmore productive than before, depending on the type oftrailer beam.Double headed twin-arc SAW installationThe manipulator type MBVA 550 is mounted on a compacttrack, which requires a minimum amount of floorspace. It is sited so that the unit can travel along thelength of two side-by-side welding fixtures, welding oneassembly while the second unit jig is being unloadedand re-loaded. The column is fitted with 180 degree rotationto allow for positioning the boom over the fixtures.The carriage carries a special OPC flux recoveryunit, and a TPC 75 pressure tank for delivering flux tothe two A6 welding heads, which deliver twin wires viabent D20 contact tubes. The arrangement allows forwelding web widths from 70mm to 800mm. A VEC motorgiving a tacho feedback into a PEG 1 control unitprovides accurate carriage travel along the track that islong enough to cover the fixture and parking areas.The welding heads are positioned and guided alongthe length of the beam by GMD guidance units, whichcontrol the vertical slides, and complete horizontal carriageallowing for motorised movement along the fulllength of the boom.Welding voltage and current are pre-set and continuallymonitored by two PEG 1 control units, giving constantstable conditions.For safety and optimum use of space, the weldingand control cables are housed in a cable chain that is fittedwithin the rail assembly. The cables run the full12 • Svetsaren nr 3 • 2000

OK Tubrod 14.00S (with OK Flux 10.71)OK Flux 10.71AWS A5.17-89: F7A2-EC1EN 765: S A AB 1 67 AC H5Table 1. Wire and flux classifications.length of the track, between the carriage and floor sitedLAE welding power sources.Apart from the welding parameters, all controls arefitted on a remote control unit, which can be hand-heldby the operator while positioning and welding thebeams.Welding consumablesIncluded in ESAB’s proposal was the use of the coredwire/flux combination OK Tubrod 14.00S-Ø2.4mm/OK Flux 10.71, equipping MDF’s SAW installation withthis proven consumable package for high speed filletwelding.OK Tubrod 14.00S is a metal cored wire providinga deposition rate that is up to 20% higher than a solidwire of the same diameter, depending on the weldingapplication. It has been designed for use with OK Flux10.71, an agglomerated, aluminate-basic flux that isslightly Si and Mn alloying. Table. 1 gives the wire andflux classifications.The combination is used when high integrity weldedjoints are required in mild and medium tensile steels,providing an excellent bead appearance in single andmulti-layer butt and fillet welds with good impacttoughness down to –20ºC. It is suited for both singlewire and twin wire applications. The slag detachabilityis good, also in narrow joints.The MDF application consists of the simultaneouswelding of two fillet welds with twin arc heads in the PBposition (see photo). The flat strip varies in thicknessfrom 4–8mm, whereas the vertical plates have a thicknessbetween 8–20mm.One advantage reported by MDF is that thewire/flux combination gives a round, but relatively flatbead penetration. Even when welding 8mm sheet, noburn-through problems occur, as encountered regularlywith the old station using solid wire.A second benefit is that the various beams, regardlessthe material thickness, can be welded at the sameparameter setting of 580A/29V and 130cm/min. travelspeed. This avoids the time consuming resetting of parameterswhich adversely effects the production efficiency.A third advantage reported is the better slag detachability,saving time in the manual removal of slag.Further, MDF are very satisfied with the appearanceof the welds especially the blending of the toes.The latter is crucial for trucks, since the dynamic loadthey are subjected to can lead to the formation of fatiguecracks when welds do not smoothly blend with theplate material.Coupled with the greatly increased productivitythese benefits have helped to ensure that MDF remainsat the leading edge of trailer beam manufacture.Figure 2. SAW with OK Tubrod 14.00S/OK Flux 10.71.Note that the slag is self releasing.Figure 3. The self-released slag is easily removed.Figure 4. Bead appearance. The standing fillet weld is flatwith a smooth blending of the toes.About the authorsShaun Studholme, Product Manager, Cored Wires inESAB Group (UK) Ltd. He is responsible for cored wiremarketing and is based at Waltham Cross, UK.Derek Harvey joined ESAB in 1983 as a Service Engineer,and became a member of the arc-equipment technicaldepartment, based at Waltham Cross some yearslater. In 1993 he was appointed Sales Manager for Weldingautomation Equipment and has responsibility for thesale of automatic SAW, MIG/MAG, and mechanised TIGequipment.Svetsaren nr 3 • 2000 • 13

Newly-developed consumablemakes thin-plate welding moreeffectiveby Lars-Erik Stridh, ESAB AB, GöteborgAs a result of increasingly fierce competition from low-cost countries,rapid changes are taking place within the welding industry in Europe.A large part of the heavy welding industry is moving its productioneastwards, to countries with low labour costs, leaving behind itindustries with skilled and mechanised welding. Europe has a numberof major automotive producers with many suppliers, most ofwhom have introduced robotic welding into their production process.The consumables these robots use for welding are generallysolid wire with a diameter of 1.0mm. The shieldinggas is often a mixed gas with a third component tominimise spatter. Continuous developments are takingplace within automotive production when it comes tosystems for joining sheet metal. These systems includebonding, resistance welding, MIG soldering, laser weldingand closing-head rivets. Arc welding still maintainsa powerful position in present-day automotive productionand, depending on the brand, there are betweenone and two kilograms of weld metal in every vehicle.Robotic welding increases at a relatively constantrate every year. The number of arc welding robots risesby around 10% every year in Europe. In the automotiveindustry, these robots are usually included in advancedcells containing several robots that work togetherin a production chain. In the fiercely competitive situationthat currently exists, it is vital for the automotiveindustry and its suppliers to make this production processas efficient as it can possibly be.BackgroundThe requirements that are set for welding for differentcomponents for the automotive industry are naturallyrigorous.After all, the vehicles that are involved are goingto transport people and attempts are constantly beingmade to find lighter materials to reduce the weight.This is done to economise on natural resources and cutfuel consumption, but, at the same time, the safety standardsfor passengers are being constantly stepped up.The plate thicknesses are small and homogeneous wireInterior from the robot cell in Göteborg where a frontsuspension part is test welded with OK Tubrod 14.11Ø 1.4 mm.is generally used. One of the problem areas is penetration.The measurement precision of the sheet-metalcomponents which are going to be welded together varies.This means that the joints are slightly different andtheir position varies somewhat.This is a problem, as thearc from a 1mm homogeneous wire has a small diameter,making the penetration profile narrow and therebysensitive to joint tolerances. In practice, this meansthat welding defects such as incomplete penetration orperforation easily occur.14 • Svetsaren nr 3 • 2000

It is also important that the transition between theparent metal and the weld run is uniform and smooth.In other words, the fatigue strength must be high. Thischaracteristic is becoming increasingly important asmore and more high strength steel is being used instructures to save weight by reducing plate thicknessProductivity and cycle times in the robot cell arevery important when it comes to keeping costs down.As a result, attempts are made to increase the weldingspeed whenever possible. This leads to another importantfactor – the hardness of the weld metal and theHAZ (heat affected zone). The heat that develops inthe arc from a homogeneous wire is relatively low andthis results in rapid cooling and the risk that the hardnesswill be too high and the weld joint will therefore bebrittle.New approachESAB’s process know-how and collaboration with differentsuppliers to the automotive industry and with theautomotive industry directly, in combination with thesecustomers’ production expertise, has resulted in a newconcept for welding thin plate, which can now be usedsuccessfully within the automotive industry.When it comes to welding thin plate, most peopleassume that they should use solid wire with a small diameter.Few of them consider using a metal-cored wirewith a larger diameter. However, this is exactly wheredevelopments have led – namely to robot welding usinga metal-cored wire with a diameter of 1.4mm.The product is called OK Tubrod 14.11. It is a weldingwire that has been developed to suit robot welding.It is therefore easy to feed, as it must not cause feed disruptions.The arc is stable and produces a minimum ofspatter and one very important characteristic is that it ispossible to weld with high currents and relatively lowarc voltage with no reduction in arc stability. This hasbeen made possible by target-oriented developmentwork.Customer applicationsThe following example illustrates the advantages. Asupplier to the automotive industry welds many differentsmall components. The company uses 1.0mm solidwire and, to obtain the widest possible penetration, ituses pure carbon dioxide as the shielding gas. Six robotswork together in a robot cell. A centrally-located weldingtable is filled with six identical components and itthen rotates one-sixth of a revolution after each weldingoperation. The six robots weld different parts of thecomponent simultaneously, which means that the weldingtimes are different and some robots have to wait afew seconds while the others finish welding.The waitingtimes are not that long – anything from four to ten seconds– but, in view of the fact that there are six weldingoperations in the total cycle, the total waiting time canbe a minute or two. The refilling time in the cell is shortand the cell welds continuously, so there can be as muchas an hour of non-productive time during the course ofExample of the very good penetration also at high weldingspeeds, in this case 27 mm/sec.A very common joint; overlap. Plate thickness is 1.5mmand welding speed in this case 32 mm/sec.a day. Over a month, this makes 20 hours. The productioncost in an uncomplicated robot cell with one robot,one positioner and one operator is around SEK 1,000an hour.The production cost in a complicated robot cellwith six robots is naturally much higher. So the cost ofthis ”waiting time” is very high.As this company is currently operating at maximumcapacity when it comes to what solid wire can achievewhile maintaining approved quality levels, tests wereconducted using OK Tubrod 14.11, 1.4mm. In thetests that were conducted using a robot at the ESABWelding Centre in Göteborg, it was found that thewelding speed could be increased from 18 mm/sec forsolid wire to 30 mm/sec for flux-cored wire. This meansthat the whole of the waiting time described abovecould be eliminated for some robots and that the totalcycle time could also be reduced by synchronising thewelding speed of the robots.The photographs show examples of the surface appearanceand penetration during these welding tests.Another example from another supplier who alsowelds components for the automotive industry is shownSvetsaren nr 3 • 2000 • 15

Part from car industryWeld length: 31 cm.Solid wire OK 14.11 DifferenceCycle time (s) 58.6 40 –31%Welding speed (m/min) 0.6 1.5 +150%Welding time (s) 31 12.4 –60%Robot motion time (s) 27.6 27.6Cycle time/unit (s) 58.6 40 –31%Reloading time (s) 10 10Number of units/h 52 72 +38%OK 14.11Solid wireWire consumed/unit (kg/unit) 0.014 0.014Wire price (£/kg) 4:36 0:77Wire cost (£/unit) 0:0612 0:0106Shielding gas consumed (m 3 /unit) 0.014 0.018Shielding gas price (£/m 3 ) 2:83 2:47Shielding gas cost (£/unit) 0:0400 0:0400Energy cost (£/unit) 0:0047 0:0047Robot + operator cost (£/h) 103:06 103:06Robot + operatos cost (£/unit) 1:43 1:68Total cost (£/unit) 1:55 1:73in the table. In this table, the cost is presented for theprevious method of welding with 1.0mm solid wire andis compared with the results for the same componentusing OK Tubrod 14.11, Ø1.4mm cored wire.AdvantagesThe reason why the use of this relatively thick, metalcoredwire, OK Tubrod 14.11, has been given such agood reception is quite naturally largely due to the opportunityto reduce the total cost by cutting the cycletimes as a result of the improvement in productivity. Inaddition, the welding quality is also enhanced. The rungeometry produces a smooth, fine transition to the parentmetal. As penetration is wider and more reliable,welding is now also more tolerant as far as gap variationsare concerned, thereby reducing the number ofwelding defects and the number of rejects. This representssavings that directly affect the profit margin.Whatis more, the amount of spatter from the wire is also lower,thereby reducing the number of stoppages to cleanfixtures. Furthermore, the cleaning of gas hoods whichthe robot performs at the cleaning station is reduced by50%, with the result that the cycle time is even furtherreduced.SummaryThere is excellent potential for streamlining the robotwelding of thin plate This applies particularly to theautomotive industry and its suppliers who demand highproductivity and high and reproducible quality. It is,however, important, when introducing a new consumablefor welding which can cut cycle times, that thewhole production chain is taken into account, in orderto avoid creating a bottleneck further down the chainand thereby losing the savings that are made in thewelding cell. By planning the welding operation carefullyand adapting the remainder of the productionchain, a great deal of money can be saved and the automotiveindustry in Europe can maintain its competitiveedge and keep jobs in Europe.About the authorsLars-Erik Stridh, EWE, graduated from Bergsskolan in1982. He worked three years as a welding engineer at arepair and maintenance company in Göteborg and afterthat 13 years as product manager for flux cored wires ata competitive company. Lars-Erik Stridh joined ESAB in1999, is based in Göteborg but works on ESAB’s totalmarket.16 • Svetsaren nr 3 • 2000

The new PEH Process Controllerhas been well received by thewelding market. So far, more then1000 units have been delivered.The PEH Process Controller isnot only taking care of the weldingparameters such as current, voltageand travel speed but optimises thebest welding performance for thewelding parameters, wire diameter,start, stop and the material to bewelded. The unit has a userfriendlymicro processor and a bigdisplay on which all the parametersare showed. The unit can alsocalculate the heat input and showit on its display before and duringwelding. It is possible to pre-set allparameters before welding andstore ten different welding parameterset.The PEH Process Controllerhas several menus; two for thewelder and two for set-up and installation.This process controller issuccessfully used for stationarywelding heads, tractors, column &booms and special customised solutions.Stubends& SpatterESAB supplies consumables and equipment foryet another LNG storage tank projectPEH Process Controller.Great success withthe new ProcessControl system fromESABPicture: Courtesy of CBkIThere is a growing interest in theuse of natural gas as a source ofenergy. Much of the gas resourcesin the world are, however, generallylocated far from the main consumptionareas. For this reason theneed for transportation and storageof gas is increasing in manyparts of the world.ESAB has an impressing trackreference in supplying weldingconsumables and equipment forlarge LNG tank constructions. Themajority of the large land basedtanks are constructed in 9%Nisteel and the gas is stored in a liquefiedcondition at temperaturesbelow –105°C.In May 2000 ESAB receivedan order for consumables andwelding equipment for the weldingof land based LNG tanks(140.000 m 3 each) for a gas terminalin Izmir, Turkey. (The contractoris EgeGaz and the project managementis made by CB&I.)The consumables including theelectrode OK 92.45 (AWS 5.9ENiCrMo-3) as well as the fluxand solid wire combination OKFlux 10.16/OK Autrod 19.82 (AWS5.9 ER NiCrMo-3) have been suppliedand a customer designedSAW equipment, Circotech, for the2G SAW welding inside the tank.Would you like more informationon these products, pleasecontact ESAB at e-mailconsumables@esab.se or fax+ 46 31 509 170.Svetsaren nr 3 • 2000 • 17

ESAB and GEISMAR co-operate successfully around Flash Butt Weldingof rail profiles and rail frogsESAB Welding Equipment AB,Automation & Engineering, hasestablished a partnership agreementwith GEISMAR Société desAnciens Établissements in France,relating to the delivery of flash buttwelding machines for welding railprofiles and rail frogs.GEISMAR has the know-how,resources and products in the fieldof joining of rails and frogs includingequipment and processes neededto complete this process. Withthe ESAB welding equipment theirspecial market organisation can nowsupport and supply the customerswith complete lines for rail joining.ESAB and GEISMAR receivedtheir first order as a result of this cooperationin 1998. The welding machinewas delivered to JR-West inOsaka, Japan in November of 1999and is now in full production.Another two new contracts fordelivery year 2000 have beensigned. The first one for BulgarianState Railways with delivery at theend of June and the second to LatvianState Railways with delivery inNovember.The parties are working closelytogether on new projects and thereare a number of even more promisingprojects coming up within thenear future.OK 92 05 improved SMAW electrode for welding pure nickelOK 92.05 is a basic type electrodefor joining pure nickel in wroughtand cast forms. It can be used tojoin dissimilar metals such as nickelto steel, nickel to copper, copper tosteel and to surface steel.OK 92.05 produces an austeniticweld metal and fulfils AWS/SFA 5.: ENi-1. A lab applicationwas carried out at the ESAB ProcessCentre in Gothenburg wherecopper was joined to steel. In thiscase, the copper was not pre-heatedbecause of its thickness, but, in caseswhere thicker or larger piecesare to be welded, pre-heating in excessof 300°C is normal for copper.A three-layer buffer area waswelded onto the copper. The bufferlayer was ground to obtain a total70° wide angle and the root runwas then performed with OK 92.05 2.5 mm. The joint was filled infour passes using 3.25 mm electrodes.The interpass temperaturewas kept at 150°C and the object3 buttering layers withOK 92.05was allowed to air-cool to roomtemperature.The current was 55 amps forthe root run and 115 amps DC+for the fill.Root face 2 mm.Root opening 2 to 3 mm.Thickness of workpiece 5 mm.Joint geometry 70°.18 • Svetsaren nr 3 • 2000

New catalogue aboutSAW from ESABESAB has put together a 44-pagecatalogue about submerged arcwelding. In addition to product information,it also contains usefulinformation about the propertiesof different types of flux and theway these properties affect weldingresults. A Quick Selection Guideshows which flux and wire combinationscorrespond to different ENand AWS classifications, togetherwith an explanation of the waythese classifications should beinterpreted. There is a special sectiondealing with ESAB’s differentpackaging types, such as Big Barreland Big Bag, which offer bulk usersrational flux handling. The advantagesof the new Eurospool andthe Marathon Pac bulk pack arepresented in another chapter in thecatalogue.Other valuable informationprovided in this new catalogue includesthe way productivity andwelding results are affected by thepolarity of the welding current andwhether one, two or three wiresshould be used or the addition ofmetal powder or cold wire. Thecatalogue also explains how to performa welding cost estimate, usinga calculation template.The new SAW catalogue, whichis available in English, is recommendedfor everyone involved withsubmerged arc welding. It can beordered from ESAB’s Europeansales companies.World’s largest cutting machine to Meyerwerft inGermanyESAB-Hancock has received amajor order from the Jos. L. Meyerwerftshipyard in Germany. Tocombat the competition fromAsiatic yards, Meyerwerft is expandingits production capacity byinvesting somewhere in the orderof DEM 200 million. Among otherthings, these investments include atotally new panel line with themost modern cutting technology.Meyerwerft selected ESAB-Hancock for this order which isworth several million DEM. Itcomprises a 28 m wide TELEREXTXB 25000 panel machine, aWelding defectsand the subsequentrepairand warrantycosts can bedue to negligenceor alack ofknowledgewhen itcomes to thestorage and handling of consumables.ESAB is now publishinga revised version of its brochureentitled “Recommendations forthe storage, redrying and handlingof ESAB welding consumables”.This brochure provides instructionson the way stick electrodesand wires should be stored andNUMOREX 6500 trimming machineand the associated environmentalequipment.The automation level of thecutting unit and the specified precisionare the highest that are technicallyfeasible at the present time.The decisive factors when it cameto capturing this order wereESAB-Hancock’s technical system,combined with the high level of reliabilitydemonstrated by previouscutting equipment which ESAB-Hancock has supplied to this shipyard.Storage and handling of consumableshow they can be reconditioned afterincorrect storage. Suitableequipment for storing and drying,as well as different types of packagingwhich reduce the risk ofmoisture absorption, are also described.A special section is devoted tothe handling of flux for submergedarc welding, together with the specialrequirements imposed on thestorage and handling of aluminiumwires and flux-cored wire. This newversion of “Recommendations forthe storage, redrying and handlingof ESAB welding consumables” iscurrently only available in Englishand can be ordered from yournearest ESAB office.Svetsaren nr 3 • 2000 • 19

ESAB pulsed gas-shielded metalarc brazing of surface-coatedsheetsby Dipl.-Ing. Hendrik Rohde, Jochen Katic and Dipl.-Ing. Rolf Paschold, ESAB GmbH, Solingen1. Gas-shielded metal arc brazingBrazing is a process for joining metallic materials withthe aid of a melted filler (solder), the melting temperatureof which lies below that of the parent metal. Theparent metal is wetted, without being melted.In Gas-shielded Metal Arc (GMA) Brazing,copper-based alloys are often used as the filler, themelting temperature of which is below that of the steelto be joined. In an ideal situation, the parent metal isnot melted at the edges. Although the arc, which burnsunder a shielding gas atmosphere, is used to warm theparent metal and melt the filler, the process is muchmore like soldering. Suitable shielding gases for GMA-Brazing are inert gases like Argon but gas mixturesconsisting of Argon and small amounts of active gaseslike Oxygen are more common. Because of that theprocess is called GMA-Brazing including MIG- andMAG-Brazing.2. Area of applicationSheet steel and steel sections are more and more frequentlyprovided with protection from corrosion inthe form of an aluminium coating or layers of zinc, appliedeither electrolytically or by hot-galvanising. Typicalareas of application are vehicle bodywork, componentsused in ventilation, cooling and air-conditioningequipment, household equipment, fire-resistant doors,roof and facade components in the building industryetc. Of course, many of these components have to bejoined.Figure 1. Front and back of a GMA brazing seam on vehiclebody panels. A residual zinc coating is retained adjacent tothe seam and on the back.3. GMA-brazing is given corrosionprotectionWhen welding galvanised structures, the evaporation ofthe zinc close to the seam causes a zone which is proneto corrosion because of the lack of a protective layer.Wires of the type EN 440 – G2Sil are also used to reducethe tendency to produce pores, the weld metalfrom which offers no rust protection whatsoever. In thiscase the destroyed corrosion protection has to be restoredsubsequently at considerable expense, e.g. by regalvanising.In contrast, copper wires are used in GMA-Brazing, which produce a corrosion-resistant solder.Copper is characterised by high solubility for zinc. Anexample of this is provided by the various brass alloys.The melting range of the CuSi3-alloy OK Autrod 19.30is approximately 910–1025°C, the melting point of zincis 419°C. During brazing, the liquid zinc remaining onthe surface of the sheet metal is included in the solderalloy, as a consequence of which a brass solder is produced.This applies particularly to the transitionbetween the solder and zinc top layer adjacent to theseam. In the transverse micro-section illustrated (figure2) the bronze solder can be seen on the right side. Thelight yellow colouring indicates the low proportion of20 • Svetsaren nr 3 • 2000

-BrassSteel-Brass (light)Figure 2. Transition from copper braze to galvanized basematerial. The braze and the zinc coating mix to form brass.zinc. This mainly involves -brass. As the transitionfrom the solder to the remaining zinc layer is approached,the proportion of dark coloured areas increases.The concentration of zinc in the solder is higherhere, ß-brass is present. The fluid transition from theCuSi-solder via a mixed layer consisting of brass to thezinc produces a sealed corrosion protection layer. Thisalso applies to the back of the weld on which a residuallayer of zinc is retained, even with thin sheet. TheESAB pulsed GMA-Brazing process makes subsequentcorrosion protection superfluous, digital regulationof the parameters reduces the evaporation of zincnext to the seam and from the back of the sheet.4. Heat input and Zinc vapourThe boiling point of pure zinc is 907°C. Zinc begins toevaporate from this temperature onwards. As theamount of heat input into the galvanised sheet increases,a larger quantity of zinc evaporates. The zinc vapourcounteracts the transfer of droplets and deflects thedroplets. Targeted transfer of droplets into the moltenpool becomes impossible; the result is considerable formationof spatter and at the very least a seam with anunattractive appearance. Therefore, when GMA-Brazing the rule is: Only as much heat as necessary!5. Pulsed GMA-brazing using the ESABAristo 2000-SystemA few users of the GMA-Brazing process have beenworking to date without a pulsed arc, which is only advantageousin the PG-Position. In these cases, the processtakes place within the short arc mode. The shortcircuits associated with this between the wire electrodeand the parent metal lead to considerable spatter formationif the power source is not sufficiently well regulated.Theheat input can only be controlled to an unsatisfactoryextent. In addition, the welder or “brazer”must adhere to a very constant contact tube distance aseven slight deviations lead immediately to considerablechanges in the parameters and consequently impair theprocess and the result. Handling is difficult and thewelder has the result “in his hands” in a very real sense.The pulsed GMA-Brazing process with the ESABAristo 2000-System offers the best possible preconditionsfor a successful bond. As a consequence ofthe process, the flow of zinc vapour counteracts the arcpressure. This must be countered by using a slightlyforehand torch action and especially an extremely shortarc. This requirement makes very high demands on theequipment.The digital Aristo 2000 achieves very high currentrise rates with very steep pulse signal edges in order toenable small droplets to be transferred to the moltenpool in a targeted way with short pulse current times.The digital regulation system has to work extremelyquickly and precisely to achieve this – a requirementwhich the ESAB Aristo 2000-System fulfils exceptionallywell.Successful pulsed GMA-Brazing also makes highdemands on the wire feed unit because the process doesnot tolerate even slight changes in the rate at which thewire is fed.The regulated ESAB wire feed system keepsthe speed required at a constant level regardless of externaldisruptions.With the ESAB Aristo 2000-System, handlingpulsed GMA-Brazing is less “the driving force for theweld” because the tolerance is much greater in sofar asthe distance away of the contact tube is concerned. Theapplication of heat is reduced; where very thin bodyworksheet is concerned, there is less risk of the seamcollapsing.Taken as a whole, the ESAB technology providesa better result in sofar as quality assurance, corrosionprotection and the appearance of the seam areconcerned.The digital Aristo 2000 system used offers both theconvenience of a synergy setting and the possibility ofoptimising all the parameters relevant to the process individually.The values produced can be filed on a PC-Steel sheetFigure 3. Transverse sectionthrough GMA -brazing seamon a body panel (s = 0.8 mm).Location of section: undersideof panel. A residual zinc coatingis retained.Zink coatingSvetsaren nr 3 • 2000 • 21

Cuprous oxide Cu 2 OFigure 6. Dark-field image of the CuSi3 braze when usingan M13 protective gas. The few eutectic precipitationscontain only small fractions of Cu 2 O.Figure 4. ESAB Aristo 2000 – LUD 320.memory card and loaded into the system again whenrequired. If the arc power is to be adjustable continuouslyover a certain range, the user can program hisown characteristic curves for synergy without enteringinto the system. In this way, he can combine the individualityof his optimised setting with the convenience of asynergy. Using this PC-memory card, we can also findparameters for you at our premises, optimise and storethem. Then you simply load these data into your LUDand start.6. Wire for GMA-brazingA number of different copper wires can be used forGMA-Brazing. Normally, the 3% Si-alloy OK Autrod19.30 (DIN 1733: SG-CuSi3) is used:Wire Cu Si Mn Meltingrange °COK Autrod 19.30 Basis 3.0 1.0 910-1025Figure 5. Transverse section through ESBA GMA-brazedjoints on vehicle body panels (s = 0.8 mm) with differentgap widths. The braze flows deep into the gap.The wire diameter 1.0 mm is the main one used.Delivery is usually on 15 kg basket spools. For mechanizedand fully automated systems OK Autrod 19.30Ø1.0 mm is also available in the ESAB MARATHONPAC TM Octagonal.OK Autrod 19.30 is particularly suitable for GMA-Brazing. Hardly any spatter is produced when combinedwith the ESAB Aristo 2000-System. No pores orcracking of the solder was found in the brazing specimensinvestigated. No scales are formed and there isonly a very thin layer of slag on the surface. The ESABOK Autrod 19.30 provides very good wetting and gapbridging (figure 5). As a consequence of capillary action,the solder flows into the air gap of overlap jointswell. The relatively soft solder makes it easy to removethe weld reinforcement, in so far as this is at all necessaryto produce a flat seam. When removing it, the zinclayer alongside the seam is damaged far less than is thecase with hard weld metal.7. Shielding gases for GMA-brazingPure argon is frequently used in practice for GMA-Brazing. However, gases with a proportion of active gasare also suitable for GMA-Brazing, e.g. gases EN 439-M12 with CO 2 -proportions of 1–3%. More recent investigationsat ESAB have shown that the use of anM13 shielding gas complying with EN 439 (Ar+1% O 2 )is advantageous. The surface tension of the molten poolis reduced, as a consequence of which the flow and wettingcharacteristics are improved significantly. At thesame time the stability of the arc improves. No scalesare formed in the seam and it has an excellent appearance.However, the use of shielding gases containingproportions of active gas raises a number of questions.Copper forms copper oxide (Cu 2 O) when combinedwith dissolved oxygen. Cu 2 O is deposited at the particleboundaries which can tear open during cold forming. Ingeneral, a very brittle microstructure is produced. As aconsequence of the embrittling effect of the copper oxide,only well de-oxidised types of copper are deemed22 • Svetsaren nr 3 • 2000

suitable for welding. More precise investigations wereundertaken at ESAB to establish whether using shieldinggases with an active gas content has a disadvantageouseffect on brazed seams. It became apparent duringthe latte that only extremely small proportions ofcopper oxide can be detected in the solder and thatthese are only present in a small number of zones containingeutectic separations. The silicon present in OKAutrod 19.30 has a deoxidising effect and keeps theCu 2 O-proportions very low.As small proportions of Cu 2 O are only present inrestricted areas and no marked particle boundary filmswere found anywhere, no embrittling effect is to be expected.Consequently, there are no objections to smallproportions of active gas in the shielding gas. This wasalso supported by the investigations undertaken onstrength.8. Strength of the brazed jointsPulsed GMA-brazed joints were produced on an overlapjoint in electro-galvanised sheet metal bodywork0.8 mm thick. OK Autrod 19.30 ∆1.0 under shielding gasM13 with 1% O 2 and the ESAB Aristo 2000-Systemwere used. Then flat tensile test specimens were takenand tested:of the process because the evaporation of the zinc isstronger, land before the torch and are reliably meltedagain.Molten poolGMA-Brazing can be done with the molten pool runningslightly ahead. This is a little strange to theMIG/MAG-welder at first because he usually has to ensurethe avoidance of bonding errors and reliable penetration.However, deep penetration is undesirable inGMA-Brazing; it is only necessary to ensure good wetting.10. ConclusionESAB provides all the pre-conditions for successfulpulsed GMA-Brazing. The Aristo 2000-System makesdigitally regulated power sources and wire feed devicesavailable which fulfil the high demands of the pulsedGMA-Brazing process in the best possible way. Combinedwith the wire electrode OK Autrod 19.30, brazedjoints are produced which demonstrate the best qualityand excellent mechanical quality values.Tensile strength N/mm 2354352350348346344342340353345352The position of the fracture in the tensile test specimenwas always in the unaffected parent metal! Thereforethe ESAB GMA-brazed joints fulfil the demandsmade of the joint completely.9. Suggestions for practical useThe optimum parameters are more difficult to set forGMA-Brazing than for MIG/MAG-welding. The thicknessand position of the zinc layer, in particular, play avery large part. Setting all the pulse parameters individuallyis indispensable for the best possible result.Torch positionIn GMA-Brazing, the torch position can have a considerableinfluence on the formation of the seam and theintroduction of heat into the parent metal, as inMIG/MAG-welding. Less heat is brought into the galvanisedparent material if the torch is in a forehand position.It causes a smaller quantity of zinc to evaporateand the degree to which droplet transfer impaired issignificantly lower. With the torch held in a forehandposition, the brazed seam is flatter and somewhat wider,but more importantly, there is less spatter. The unavoidableamounts of spatter, which occur at the startAbout the authorsHendrik Rohde graduated in 1991 as a mechanical andwelding engineer from the Technical University ofMagdeburg and joined ESAB Germany in the same year.In 1995, he became a European Welding Engineer. He isnow product manager for arc welding products withGMAW as the main field and he also specialises inmodifications for the use of welding machines withmechanised equipment.Jochen Katic is an EWS and works as a demo-welder formechanised welding processes. He joined ESAB GmbHSolingen in 1990. Mr. Katic is also a specialist in weldingwith flux-cored wires and he is often involved in researchand development projects for customer applications inautomatic and robotic welding.Rolf Paschold, product manager at ESAB GmbHSolingen (Germany), graduated in 1990 as a mechanicaland welding engineer. He joined ESAB in 1991 and is thesales support manager for welding consumables. MrPaschold has always shown a special interest in tailormadeprocess applications developed together with thecustomer.Svetsaren nr 3 • 2000 • 23

The use of rutile cored wires forwelding high strength steel incrane fabricationby Ben Altemühl, ESAB B.V., Utrecht, The NetherlandsHigh strength steels are increasingly applied in crane fabrication, withthe aim to obtain weight savings or a higher lifting capacity. Simultaneously,cored wire welding is becoming more popular. This has to dowith the high quality demands cranes are subjected to for securityreasons, but also with the higher welding productivity cored wires offer.On the European welding consumable market, theavailability of cored wires for high strength steel hasbeen limited to mainly metal-cored and basic types. Recently,however, ESAB has introduced two rutile typeswith a minimum yield strength of 620 and 700 MPaunder the product names OK Tubrod 15.07 and OK Tubrod15.09 respectively.The wires are characterised by high welding productivity,good mechanical properties, a very low weldmetal hydrogen content, and above all, excellent weldability.ESAB developed these wires at the request of severalEuropean crane fabricators, among which theDutch company Huisman-Itrec. They tested the OK Tubrod15.09 for welding Weldox 700 and have gained productionexperience in a number of projects.OK Tubrod 15.07 is still in its testing stage. At thismoment, it is being tested for the mechanised weldingof pipelines in X80.This article will introduce the new rutile coredwires for high strength steel, while describing the experiencesof Huisman-Itrec with the OK Tubrod 15.09.Huisman-ItrecHuisman-Itrec B.V. in Rotterdam, is the result of a mergerin 1981 between the crane fabricator Huisman andthe engineering bureau Itrec. Their most important activityis the construction of cranes and other liftingequipment for the offshore industry, the dock industry,civil works and shipbuilding. With design facilities forengineering, hydraulic and electric propulsion systems,and for software, the company delivers client specifiedinstallations. Huisman-Itrec specialise in systems thatare not available on the market as standard products.Examples are cranes for deep-water applications, andship motion compensation systems. Other productsbuilt by Huisman-Itrec are floating sheerlegs, self propelledheavy transporters, equipment for installingpipelines on the seabed, drilling equipment, and evenamusement park attractions. These products are deliveredto clients all over the world.The company constructs according to the requirementsof the leading approval societies in this branch ofindustry (e.g. Lloyds), and execute a high quality standard.When not building on site, products are testedwith in-house facilities, before delivery.AWS A5.29-98 EN 12535-00 ApprovalsOK Tubrod 15.07 E101T1-K7M H4 T 62 4 Mn2Ni P M 2 H5 –OK Tubrod 15.09 E111T1-GMH4 T 69 4 Z P M 2 H5 ABS*, LR*Table 1. AWS and ENclassifications and approvals.*= limited approval.24 • Svetsaren nr 3 • 2000

Figure 1.Vertically-up weldingof a crane beam inWeldox 700.Figure 2. Vertically-up welding of a crane beam in Weldox700.OK Tubrod 15.07 and 15.09Both types are all-positional rutile cored wires withAWS and EN classifications according to table 1. Thestrength properties are tuned for high strength steelwith a minimum yield strength of 620 and 700 MPa,with good CVN toughness at –40ºC. Table 2 gives theall-weld metal chemical composition and mechanicalproperties.The wires are developed for all-positional weldingunder 80%Ar/20%CO 2 shielding gas, falling within EN439 class M21. Vertical down welding, however, is notrecommended because of the high risk of cracking inthe first thin layer; especially in fabrications with a highrestraint.It concerns butt-closed cored wires with a filling degreeof approximately 18%. The slag is fast freezing tosupport the weld pool during positional welding. Thearc action is spray-arc at all welding currents, and theweldability is excellent. Another advantage is that, withthe same wire size, a uniform parameter setting can beused when components have to be welded in severalpositions.The high productivity, compared to solid wires andbasic cored wires, becomes apparent in positional welding(PC, PF and PE). Vertically-up welding with a depositionrate of 3kg/h, for instance, is attainable.The weld metal hydrogen content falls within ClassH5 of EN785 for the operating envelope of parametersand corresponding stick-out lengths, which is exceptionalfor rutile consumables. This is of great importancefor the welding of high strength steels. Normally,the weld metal has a higher Carbon Equivalent thanthe high strength parent metal, and therefore it willundergo the austenite-ferrite transition later. For thisreason, hydrogen in the weld metal will not be able todiffuse to the heat affected zone and remain in the weldmetal.Add this to the limited heat input, needed to givethe weld metal sufficient strength properties, and all ingredientsare present to cause hydrogen induced cracking.Low-hydrogen weld metal is therefore crucial forsuccessful crack-free welding. This is also reflected bythe preheating recommendations for Weldox 700,which are based on H5 class filler materials (Table 3).The wires are not recommended for constructionsthat are submitted to a stress relief treatment, whichwould result in partial loss of toughness properties. Inthese cases, the use of a basic cored wire is advised.Experiences with OK Tubrod 15.09 in cranefabricationThe introduction of OK Tubrod 15.09 at Huisman-Itrecis part of a general transition from solid to cored wirewelding, carried through over the past years by thewelding department with the aim to improve the alloverwelding productivity. An additional advantage, especiallywith rutile cored wires, is that also temporarywelders master the required skills relatively quickly,which enhances the flexibility required by production.At this moment, over 85% of all weld metal is depositedwith metal cored or rutile cored wires, whichbrought along a substantial increase in productivity.It concerns mainly manual welding, but the welding departmentis investigating the possibilities of light mechanisation.Allwelders are certified up to H-L045 (6G).%C %Si %Mn %Ni %Mo %P %SOK 15.07 0.04-0.07 0.30-0.50 1.45-1.75 2.30-2.70 – 27 at –50ºC)OK 15.09 >690 770-900 >16 >41Svetsaren nr 3 • 2000 • 25

Combined thickness (mm)t1+t2+t3= 10 20 30 40 50 60 70 80 90 100 110 120 130WELDOX 70075ºC100ºC 150ºCTable 3. Preheatingrecommendations forWeldox 700 based on amaximum heat input of1.7kJ/mm and lowhydrogenweld metal(EN 785 class H5).Correct heat input 1.2-1.4KJ/mm/Tp 80ºC/Ti 170ºCTensile test Rm (MPa) Re (MPa) A (%)848 825 15.6CVN at –40ºC (Av.3) WF FL FL+2mm FL+5mm WR FR FR+2mm54 54 161 161 33 39 122Hardness HV10 (Av.3) Weldox 700 WBZ Las WBZ Weldox 700Root 273 434 297 417 279Center weld 276 343 259 331 286Bend test Magnaflux UltrasonicOK no indications no indicationsHigh heat input 1.7-2.0 KJ/mm/Tp 80ºC/Ti 190ºCTensile test Rm (MPa) Re (MPa) A (%)841 780 15CVN at –40ºC (Av.3) WF FL FL+2mm FL+5mm WR FR FR+2mm54 102 168 123 31 30 135Hardness HV10 (Av.3) Weldox 700 WBZ Las WBZ Weldox 700Root 266 397 290 395 282Center weld 266 343 289 346 861Bend test Magnaflux UltrasonicOK no indications no indicationsTable 4. Mechanicalweld metal propertiesat a correct heat inputand a too high heatinput. V-joint/ platethickness 30mm,combined thickness60mm/ Weldox 700Heat no. 366631/position PF.WF = Weld Face,FL = Fusion Line,WR = Weld Root,FR = Fusion Line Root.Figure 3. Crane pedestal part.Huisman-Itrec increasingly applies Weldox 700high strength steel for the construction of lifting equipment.The components to be welded, such as cranebeams, masts and pedestal parts, are too large to beturned, making positional welding unavoidable. Untilrecently, the Weldox 700 was welded with a combinationof coated electrodes and solid wire, but also herethe company wanted to change over to 100% coredwire welding. That is why they requested ESAB to developsuch a wire, which received a positive reply, alsomotivated from an international context.After the development of the wire, Huisman-Itrecsubmitted the first test spools to a rough test to verifythe suitability for welding Weldox 700. It concerned aV-joint in thick plate, welded in PF position withoutpreheating and without controlling the interpass temperature.Thestrength properties of the joint were measuredby tensile tests with transverse and longitudinal test bars.Cross weld, a tensile strength of 769MPa was obtained,with the rupture in the parent metal. In the longitudinaldirection, the yield strength was too low (668MPa)whereas a tensile strength of 754MPa was satisfactory.Rm Re A5 CVN(MPa) (MPa) (%) –40ºC (J)Figure 4. Vertically-up welding of a pedestal part.Weldox 700 780-930 >700 >14 >27Heat nr. 366631 826 759 15 158(Av.3)26 • Svetsaren nr 3 • 2000

The CVN toughness (Av. 3) was 53J at–40ºC for the weld and 42J for the root(welded on ceramic strip).The results ofthe side bend tests were good. Subsequentultrasone and magnaflux testingproved that the weld was free of defectsand, more importantly, cracks.WPS’esOn the basis of these results, the weldingdepartment of Huisman-Itrec decidedto continue the investigation,aiming at the establishing of suitablewelding procedure specifications(WPS) for Weldox 700. In addition, thecompany wanted to obtain a Lloydsyard approval for a project with a CVNrequirement of 27J at –40ºC, awaitingthe general Lloyds approval ESABhad requested.Table 3 gives the preheat recommendationsfor Weldox 700, based on aweld metal hydrogen content of max.5ml/100g deposited weld metal and amaximum heat input of 1.7kJ/mm. Tounderstand the effect of the heat inputon the mechanical properties, testplates were welded (8003030mm)at a correct heat input (1.2-1.4kJ/mm)and at higher heat input (1.7–2.0kJ/mm). Table 4 summarises the results.The strength requirements of Weldox700 (Table 5) were met, as well asthe maximum hardness requirement of425HV10. The same is valid for theCVN toughness of the weld; even forthe root.On the basis of these results,Huisman-Itrec was granted the local approval theyneeded for OK Tubrod 15.09, valid for one specific productand one batch. Figure 5 shows a WPS for the positionPF that Huisman-Itrec developed subsequently.In a later stage, ESAB obtained the general Lloydsapproval; be it with a limitation. For this class of consumables,Lloyds has a CVN demand of 69J at –40ºC.For rutile consumables, this is too high, however.That iswhy the approval is limited to projects with CVN requirementsof 42J at –40ºC or lower, which is sufficientfor many applications.Fabrication experienceHuisman-Itrec applies OK Tubrod 15.09 for welding inPF position. For downhand work, they kept on using ametal-cored type. After successful use on a smaller project,OK Tubrod 15.09 was utilised for a bigger project,the fabrication of a series of cranes for Mammoet B.V.The figures 1 to 4 show the application of the wire.It is applied successfully for the vertically-up weldingof crane beams, pedestal parts and other crane components.The welders are very pleased with the new consumableand also temporary workers learn to use it withinan acceptable period of time. Essential for weldingWeldox 700 is that the low heat input, needed to obtainsufficient strength and toughness, can be maintainedwell, also in PF position. This is more difficult with solidwire, basic, or metal-cored wires, because these are weldedclose to the short arc mode. The success also becomesapparent from the 100% ultrasonic and magnaflux NDTthat was performed. The defect rate was below 0.5%.About the authorBen Altemühl, BSc, welding engineer, joined ESAB in1990 as sales promotion manager for FILARC WeldingIndustries in the Netherlands. Since 1999, he has beenresponsible for the sales promotion of all cored-wireproducts within ESAB Europe’s Business Area Consumables.Svetsaren nr 3 • 2000 • 27

The new ESAB EcoMig weldingwire adopted by Fai KomatsuIndustries for welding its earthmovingequipment.by Ferruccio Mariani, ESAB ItalyHigh performance, reliable quality and product ecology are the mainreasons for the choice of ESAB OK Autrod 12.50 Eco Mig wire. At FKI,Fai Komatsu Industries, highly-developed welding systems and processesare used for welding specialized products which are aimed primarily atdemanding markets in industrialized countries.Robotic cells with fully-automated loading and unloadingsystems, combined with the latest generation ofhigh-speed welding processes, all complying with environmentalrequirements.In just the same way that a formula 1 engine has tobe filled with a sophisticated fuel in order fully to developits power, FKI has adopted a welding wire whichcomplies with the demanding requirements imposed byits welding equipment and processes to provide outstandingperformance.ESAB OK Autrod 12.50 EcoMig in the octagonalMarathon Pac not only comes up to all the company’sexpectations, it also produces other additional advantages,as we will see in the following interview.FKIFKI S.p.A. in Este (Padua, Italy) is one of the four productionunits of the Komatsu Group in Europe and specializesin the so-called “utility range”.The company was set up in 1963 with the nameFAI, Fabbrica Attrezzature Industriali (IndustrialEquipment Factory).Its initial operations focused on equipping tractorswith some added components in order to make themmore versatile and suitable for many different operations.Thisis how the so-called “terna” was born, a namewhich recalls its three functions: the tractor itself, thefront shovel and the rear excavator. During the developmentof the building trade, changes in market de-28 • Svetsaren nr 3 • 2000

mand led the “terna” to become fully independentequipment, retaining only the functions of digging andloading but keeping its name at the same time.Over the years, other products were added to the“terna” and FAI continued to expand until about 12years ago, when it came in contact with Japanese Komatsuand set up a joint venture for the production of arange of mini-excavators, a product which had not yetbeen introduced in Europe. The relationship developedand was consolidated about four years ago with thebirth of FKI, FAI KOMATSU INDUSTRIES S.p.A., inwhich 100% of the shares are owned by Komatsu. Nowadays,FKI has almost 900 employees.“Turnover in 1999 was USD 260 million, this year itwill be about 325. During the last three years, we havemore than doubled our turnover,” says Claudio Gallana,production manager, with justifiable pride in his voice“This is thanks to synergies with the Komatsu Groupand particularly to favourable trends on the market.”FKI’s market operations focus on five productlines: firstly excavators, secondly the stiff “terna” seriesthat is expanding rapidly thanks to new markets, likethe USA, thirdly the line of articulated “ternas”, similarto the previous one but with central articulation that allowsthe machine to operate in narrow environmentsand more uncomfortable situations. They are followedby the line of so-called “skid steer loaders”, small loadingmachines. This is an important product for FKI andit is experiencing a particular period of market growth.Last but not least comes the line of compact excavators,also called midi-excavators.FKI constitutes the focal point of the utility divisionwhich is experiencing powerful expansion in the KomatsuGroup, as it is the only manufacturer of thisSvetsaren nr 3 • 2000 • 29

ange of products for the European market. Utility isthe series of relatively small machines which are used inthe building trades for repair and maintenance work,like roads, pavements and so on. The market is experiencingvery favourable trends, mainly in industrializedcountries where the major infrastructure, such as roads,bridges and viaducts, has already been constructed butwhere there is a great deal of work to be done in cities,or historical centres, or constructing new apartmentblocks, where machines of this kind play a key role. Inspite of the relatively high investment cost, they are amore efficient alternative in all the above-mentionedcountries where the labour costs are really high.We asked Mr. Gallana for some information aboutmarket position, objectives and strategies.“On a worldwide scale,” he replies, “when it comesto the global market and product dimensions, it would betrue to say that Komatsu and Caterpillar are always competingfor first place. Afterwards,” he continues smilingand looking at the ground “there are some others... Anyway,not all the players are comparable in terms of productrange and type. As far as our Italian production isconcerned, it has to be said that we have an importantpresence on the Italian market; in fact, for some productsit accounts for more than 30–35%. For instance, themini-excavator made its appearance on the Italian markettogether with us. We are now also supplying theAmerican market, mainly with two product lines: “ternas”and skid steer loaders.“At this very moment, one extremely important objectiveis to keep our market shares at a high level andthis isn’t so easy because the market is growing at a reallyfast rate, even faster when we add the further positivefeedback from group synergies.“One of the main difficulties in our area is findingskilled workers. I want to give you an example; it is stilleasy enough to find young technicians if you offer themthe chance to operate a welding robot, but, when youlook for a welder who is able to handle a welding torch,that’s much harder. That’s why we have pushed the acceleratoron robotic welding, also taking account of thehigher productivity and the profit produced by the lowercost of robotic technology nowadays. We definitely needto stay on the road to productivity. At the same time, wemust take care of the balance between our growth, whichis forecast to remain good over the next few years, andthe related costs, because the favourable trend on themarket cannot last for ever.”Importance of weldingAs far as production is concerned, the five product linesare produced on three assembly lines, so there is a productmix on some lines. The majority of components arewelded inside the factory – this particularly involves themain structures of the machine, while small or minorcomponents and sub-assemblies with less rigorous requirementsare supplied by outside subcontractors.Basically the production cycle is as follows: the componentsare pre-assembled using special equipment,which is very flexible, the result of Italo-Japanese jointdesign. They are then taken to the robotic cells wherethe welding operation is performed. Robotic welding accountsfor 80–90% of the total weld, but some weldingstill has to be done manually for many reasons, such asdifficult access to the welding position and so on. Sothere is a final phase in which the small percentage ofwelding that is left is completed manually.The welding operation employs about 10–15% ofthe total work force directly or indirectly. In terms ofwelding time in the production cycle, the situation is nothomogeneous, it varies because, for some machines, allthe components are welded inside the factory. In thiscase, welding takes 30–35% of the total cycle time. Forother types of machine, only the main components are30 • Svetsaren nr 3 • 2000

welded inside, while minor components are subcontractedto outside suppliers. Taking account of this variability,it would be true to say that an average of 60%of the structures are welded inside.Anyone used to visiting welding departments atmechanical industries would expect to find the wellknown“atmosphere” at FKI as well: arcs crackling andflashing, the emission of fumes in the environment,piles of welded and unwelded components close towelding stations, noise... well you could not possibly bemore mistaken! With the maximum respect for sacredthings, when you enter the welding hall at FKI, you feelas though you are entering a cathedral. This is the perfectdefinition: space and airiness, a sober atmosphere,cleanliness, a lack of noise and arcs flashing. What impressesthe visitor instead is the sight, inside the hall, oftwo rows of cubic constructions, each about ten metreswide, surrounded by rail tracks: they are the roboticcells. Inside, there are the welding robots with the relatedpositioning devices. Every cell is equipped with avery effective system of electrostatic filters which trapthe last molecule of particles and fumes developed bywelding. Electric arcs, radiation, heat, fumes and noiseare therefore restricted inside the cells. This is a 93-metre line made up of six - it will be eight by the end ofthe year – robotic cells, supplied by a trolley system forloading and unloading the components in a fully automatedand randomized manner.Each robot is programmed in such a way that it canrecognize every component and carry out the relatedwelding programme. In other words, the first assemblyon the waiting list goes to the first cell where the previouswelding programme has been completed. Thissystem allows maximum flexibility in the production cycleand high efficiency, cutting all the waiting timesfrom the different preparation times for the differentcomponents.The welding process is the high-speed T.I.M.E. process,which offers very high productivity in welding. Obviously,the requirements imposed on the welding wireare really demanding: over 400 amp current (the diametersize which is used everywhere is 1.20mm), over 20m/min wire speed, a 20-metre liner guiding the wirethrough the chain system of the three-axis cartesian robotgantry up to the welding head. Last but not least, aftersuch a long journey, the wire ends up with a verylong stick-out that has to be absolutely straight!“High quality together with consumable reliabilityare basic requirements,” Mr. Gallana stresses. “Weldingis a complex problem, especially robotic welding, becauseit is affected by plant-related phenomena as well asby the consistency of the consumables – the shielding gasand wire, particularly in such a complicated process aswe have.The first and most important requirement for usis the consistency. Another basic requirement is the service;this involves a continuous search for improvements,as well as the solution to specific problems. In otherwords, the ability to conduct new tests, find fast solutionsand react quickly – to be innovative. As far as I’m concerned,ESAB fulfils these requirements.”From OK Autrod 12.51 Marathon toOK Autrod 12.50 EcoMig in the octagonalMarathon PacWe contacted Giampaolo Bellucco, the person responsiblefor auxiliary materials. “Since we introduced robotization,the need to use large wire packaging has arisen,”he explains.“As a first step, we conducted some trials with 90 kgbobbins, but the real solution came when ESAB suppliedus with its OK Autrod 12.51 wire in the Marathondrums. Since the beginning, it has come off best comparedwith all its competitors. We started using it and wethen continued for years, but...good, better, best, never letit rest! Recently, we performed a number of rigorouslarge-scale tests on products and suppliers and this tookus a further step forward.”“Once more, ESAB emerged as the winner with itsnew ecological wire OK Autrod 12.50 EcoMig, which wehave now definitively adopted. All the other competitorsfailed miserably because the actual results did not comeup to the promises.”Silvano Crescente, the person responsible for FMSplant, joins in. “Since I started using this new wire, I haveencountered far fewer problems on this plant. This isvery sophisticated equipment, the wire mustn’t createproblems, we use the T.I.M.E process, the programmingis fairly complicated and it does not forgive mistakeswith the welding wire. Constant, regular feed is an essentialfactor. We have six robots, since the first test we startedwith all of them, I’m talking about 35–37 pieces a day,two hours of arc time per piece on average, you can reallysee if the wire can take the punishment. As a matter ofSvetsaren nr 3 • 2000 • 31

fact, the evaluation comes out completely in favour ofESAB OK Autrod 12.50 EcoMig compared with all thewires tested.“Every stoppage costs money,” continues Mr Crescente“because a package of unreliable wire results in aone-hour stop, including checks and replacement. A reliablewire like this generates nice savings!”“We haven’t yet quantified the accuracy,” Mr. Belluccoadds, “but we have noted a number of additional advantages:lower torch and liner cleaning frequency, lessspatter, longer service life for contact tips, generallyspeaking I have noted a sharp reduction in all the componentsthat are subject to wear, which means that lesstime needs to be spent on maintenance as well. Now Imust say something about fume reduction, that’s realevidence!”Environmental considerationsAt this point, we allow ourselves the luxury – metaphoricallyspeaking – of interrupting Mr. Bellucco forjust a short digression. FKI’s industrial complex is locatedin Este, at the foot of the Euganei Hills, a wellknownarea which has become rich and famous thanksto its thermal springs and waters, a place where the environmentcreates well-being and health. It could be acoincidence, but it is noticeable that, as far as we know,FKI is the first company, or at least one of the first, inthe metal-mechanical field in Italy to have applied forenvironmental certification according to ISO 14.000and the company will shortly be receiving it.“ISO 14.000,” explains Mr. Bellucco “ is the normthat governs the environmental impact of operationsfrom every angle. We have made a clear-cut, intentional,evaluated and planned choice in this area, even if I haveto admit that complying with this standard is far moredemanding compared with what we needed to do yearsago to obtain the quality certificate according to ISO9000. How to get rid of waste, how to control air pollution,the products and their handling, the contact of differentproducts with the employees and the impact of ourproducts on the environment and so on...it’s a really demandingtask.“For many years, we developed our control systemand managed our purification systems, but another stepforward now has to be made. It relates first and foremostto people’s cultural side. The working environment ispart of our life, I mean “our” in the widest sense of theword on a world scale. Everybody must be prepared torespect the standards that eventually generate commonwelfare. In this respect, our personnel are very positiveand co-operative. Last but not least, we must rememberthat a comfortable working environment is an incentivefor higher efficiency.“An excellent illustration was recently given here byESAB’s Autrod OK 12.50 EcoMig wire, when the weldersrealized that it developed far fewer fumes.We are naturallytaking advantage of this in robotic welding becauseit reduces the frequency with which the electrostaticfilters need to be cleaned, which has an obvious advantagewhen it comes to productivity, but robotic welding isdone inside the cells while the operators are outside sothat they are not in direct contact with the arc and fumes.However, we also have semi-automatic welding sites.There are about 30 of them at which minor componentsor sub-assemblies are welded. Even if there is a fumeextraction system, the fumes developed by welding arestill immediately visible and in direct contact with thewelder’s environment.”“In the past, in order to obtain higher productivity bymeans of higher duty cycles, we made many attempts tomove from 15 kg reels to higher weight packages likeOK Autrod 12.51 Marathon, in order to reduce the stoppagescaused by changing the reel every 15 kg. Of course,everybody knows that this kind of stoppage is welcomedby welders as it often gives them an opportunity to havea short break during work.”“Well, as soon as we asked the welders to test the newecological non-copper-coated OK Autrod 12.50 wire inthe octaconal Marathon Pac we were surprised to findthat they fell in love with it. They have not only acceptedit, they have even approved it through their trade unionrepresentatives. Nowadays, it is the only wire they want.They have realized that being at the forefront when aninnovation is introduced is useful for them and not justfor the company. All of this is mainly due to the sharpreduction in fumes.”“An ecological product like this makes our life easier,even when it comes to the acquisition of ISO 14.000.“By the way, the new octagonal Marathon Pac is alsoan advantage. When it is empty, the cardboard can beeasily squashed and stacked on pallets, you can pile upmany of them in a very small space and, finally, managingrejects is less demanding from a logistical point ofview.”ESAB’s roleWe ask Mr. Bellucco to formulate a final opinion ofESAB. “When it comes to the product itself, I think I’vealready said everything. When it comes to supplier quality,I would put it this way.“Each company’s name is associated with an image,but, when you analyse the facts in depth, the ‘real’ imagedoes not always correspond to the ‘virtual’ one. InESAB’s case, I must say that the image associated with itsname is synonymous with the actual, verified truth –reliability. At least as far as we are concerned.”“Not because there has never been a problem, butbecause, whenever problems have occurred, ESAB hasalways been able to accept and resolve them, giving usthe necessary support. I have had the chance to verify theservice, reliability and consistency. I find that ESAB is aproblem-solving supplier which is available and ready towork together. It makes me feel secure. It’s more thanenough!”Mr. Bellucco’s conclusion is very gratifying for acompany like ESAB that has always wanted to work togetheras a partner alongside its customers and to pursueobjectives of common interest.32 • Svetsaren nr 3 • 2000

Figure 3. Hydraulic cylinder for moving the bucket and jib.Figure 4.Cylinder base.Figure 5.Cylinder head.OK Tubrod 14.11 has already shown itself to be extremelyeffective when manufacturing hydraulic cylindersfor excavators and other road-construction machinery.U-welds, as illustrated in Figure 7, are weldedin four passes using OK Tubrod 14.11 1.4 mm. Thisinvolves the use of either conventional MAG techniques(Table 1) or the MAG tandem method(Table 2).In comparison with the MAG tandem method,which was used in the past with 21.0 mm solid wire,the welding speeds achieved in this case in productionconditions with OK Tubrod 14.11 1.4 mm were almostable to match those of classical MAG weldingwith a wire electrode. It was even possible to increaseproductivity because the quality of the welded jointswas significantly better and more reliable.To obtain a further increase in production, it is possibleto weld the intermediate layer of relatively largehydraulic cylinders using the MAG tandem method and2OK Tubrod 14.11 1.4 mm. The reliability of theprocess is so high, as a result of the high stability of thearc and the fine feeding characteristics of the flux-coredwire, that the second flux-cored wire (slave) can be appliedwithout interrupting the welding process. At thesame time, the welding speed is naturally increased inorder to prevent the formation of an uncontrollablylarge molten pool. The top pass again reverts to weldingwith just one electrode which oscillates to producethe best possible seam surface. The second flux-coredwire is switched off again during the process. No processdisruptions or disadvantageous effects on the qualityof the seam have so far been observed.Cylinder base Piston TubeCylinder headPistonshaftFigure 6.Figure 7.34 • Svetsaren nr 3 • 2000

As a matter of principle, the MAG tandem method offersan opportunity to improve the productivity ofMAG welding. However, if this process is used withsolid wire, a few typical weak points can be observed,such as a tendency towards undercutting, high contacttip wear, the need to reset the process parameters frequently,high thermal loads on the torch and so on.Experience to date indicates that at least the directlyprocess-related defects can be significantly reducedby using OK Tubrod 14.11.About the authorKlaus Blome obtained an MSc from the Technical UniversityRWTH of Aachen. He joined ESAB Germany in1990 as a product manager for welding consumables.Between 1992 and 1997, he was international productmanager for cored wires at Filarc Welding Industries inUtrecht. He returned to ESAB Germany in 1997. KlausBlome was recently appointed regional sales managerwest and key account manager as from January 2001.OK Tubrod 14.11 Welding current (A) Voltage (V) Welding speed1.4 mm / 82/18 Ar/CO 2 (cm/min)Root 350 / 360 30 / 31 60 / 622 intermediate passes 390 / 400 35 / 36 58 / 60Top layer 410 / 420 36 / 37 40 / 42(oscillating)OK Tubrod 14.11 Welding current (A) Voltage (V) Welding speed1.4 mm / 82/18 Ar/CO 2 (cm/min)Root (single wire) 350 / 360 30 / 31 45 / 50Intermediate pass Master 400 / 410 35 / 36 80 / 85(Tandem) Slave 310 / 320 33 / 34Top pass 410 / 420 36 / 37 60 / 62(oscillating)Table 1. U-seam onhydraulic cylinders(D = 210 mm, b = 20 mm).Conventional MAG weldingwith OK Tubrod 14.11Ø 1.4 mm.Table 2. U-seam onhydraulic cylinders(D = 210 mm, b = 20 mm).MAG tandem welding with2OK Tubrod 14.11Ø 1.4 mm.✂Order form Please register me as free subscriber to Svetsaren I have changed my address Please send me more information aboutSvetsaren 3. 2000Name (please print)Position in companyCompanyAddressCountryESAB AB, SVETSAREN, Box 8004, SE-402 77 Göteborg, SwedenSvetsaren nr 3 • 2000 • 35

ESAB AB, Box 8004, S-402 77 Göteborg, SwedenTel. +46 31 50 90 00. Fax. +46 31 50 93 90Internet: http://www.esab.com