MANUFACTURING ENGINEERING

Manufacturing Engineering DefinedTechnical staff function concerned with planning themanufacturing processes for the economicproduction of high quality products•Principal role - to engineer the transition of theproduct from design specification to manufacture of aphysical product•Overall goal - to optimize manufacturing within aparticular organization©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Manufacturing Engineering Activities1. Process planning Deciding most appropriate processes and theirsequence Determining tooling requirements Selecting equipment Estimating costs2. Problem solving and continuous improvement - staffsupport to operating departments3. Design for manufacturability - serve asmanufacturability advisors to product designers©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Traditional Process Planning•Traditionally, process planning is accomplished bymanufacturing engineers who are knowledgeable inthe particular processes used in the factory and areable to read engineering drawings•Based on their knowledge, skill, and experience, theydevelop the processing steps in the most logicalsequence required to make each part•Some details are often delegated to specialists, suchas tool designers; but manufacturing engineering isresponsible©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Decisions and Details inProcess Planning•Processes and sequence - the process plan shouldbriefly describe all processing steps used on the workunit in the order in which they are performed•Equipment selection - try to develop process plansthat utilize existing plant equipmentOtherwise, the part must be purchased, or newequipment must be installed in the plant•Tools, dies, molds, fixtures, and gages - design isusually delegated to the tool design department, andfabrication is accomplished by the tool room©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

More Decisions and Details inProcess Planning•Methods - include hand and body motions, workplacelayout, small tools, hoists for lifting heavy parts, etc.Methods must be specified for manual operations(e.g., assembly) and manual portions of machinecycles (e.g., loading and unloading a productionmachine)•Estimating production costs - often accomplished bycost estimators with help from the process planner•Cutting tools and cutting conditions for machiningoperations©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Process Planning for Parts•The processes needed to manufacture a given partare determined largely by the material out of whichthe part is made and the part design itselfThe material is selected by the product designerbased on functional requirementsOnce the material has been selected, the choiceof possible processes is narrowed considerably©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Typical Processing Sequence• A typical processing sequence to fabricate a discretepart consists of:1. A basic process2. One or more secondary processes3. Operations to enhance physical properties4. Finishing operations©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Figure 41.2 - Typical sequence of processes required in part fabrication©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Basic and Secondary Operations•Basic process - establishes initial geometry ofworkpartExamples: metal casting, forging, sheet metalrolling•In most cases, the starting geometry must bemodified or refined by a series of secondaryprocesses, which transform the basic shape into thefinal geometryExamples: machining, stamping©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Operations to Enhance Propertiesand Finishing Operations•Operations to enhance properties - heat treatmentoperationsTreatments to strengthen metal componentsIn many cases, parts do not require these propertyenhancing steps•Finishing operations - the final operations in thesequenceUsually provide a coating on the work surfaceExamples: electroplating, painting©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Examples of Typical Process SequencesBasic processSecondaryProcess(es)PropertyenhancingFinishingoperationsSand castingMachiningHeat treatingPaintingRolling sheetBlanking,bending(none)ElectroplatingForgingMachining(none)PaintingExtrusion (Al)Cut to length(none)AnodizeCasting of glassPress, blowingAnnealingChem. etch©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Process Planning and the Basic Process•Process planning usually begins after the basicprocess has provided initial part shapeExample: machined parts begin as bar stock orcastings or forgings, and the basic processes areoften external to the fabricating plantExample: stampings begin as sheet metal coils orstrips purchased from the mill•These are the raw materials supplied from externalsuppliers for the secondary processes andsubsequent operations to be performed in the factory©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

The Route SheetThe document that specifies the details of the processplan•The route sheet is to the process planner what theengineering drawing is to the product designer•The route sheet should include all manufacturingoperations to be performed on the workpart, listed inthe order in which they are to be accomplished©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Figure 41.3 –Typical route sheet for specifying the process plan©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Process Planning for Assemblies•For single stations, the documentation contains a listof the assembly steps in the order in which they mustbe accomplished•For assembly line production, process planningconsists of line balancing - allocating work elementsto particular stations along the line•As with process planning for individual parts, anytools and fixtures needed to accomplish a givenassembly task must be decided, and the workplacelayout must be designed©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Make or Buy Decision•Inevitably, the question arises whether a given partshould be purchased from an outside vendor or madeinternallyIt should be noted that virtually all manufacturerspurchase their starting materials from suppliersVery few production operations are verticallyintegrated all the way from raw materials tofinished product©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Make or Buy Decision (continued)•Given that a company purchases some of its startingmaterials, it is reasonable to question whether thecompany should purchase the parts that wouldotherwise be made in its own factoryThe answer to the question is the make or buydecisionThe make versus buy question is probablyappropriate to ask for every component used bythe company©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Make or Buy ExampleThe quoted part price from a vendor = $8.00 per unit for1000 units. The same part made in the home factorywould cost $9.00. The cost breakdown on the makealternative is as follows:Unit material cost = $2.25 per unitDirect labor = $2.00 per unitLabor overhead at 150% = $3.00 per unitEquipment fixed cost = $1.75 per unitTotal = $9.00 per unitShould the component by bought or made in-house?©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Make or Buy Example - continued•Although the vendor's quote seems to favor the buydecision, consider the possible effect on the factory ifthe quote is acceptedEquipment fixed cost is an allocated cost basedon an investment that has already been madeIf the equipment is rendered idle by a decision tobuy the part, then the fixed cost of $1.75 continueseven if the equipment is not in useThe overhead cost of $3.00 consists of factoryfloor space, indirect labor, and other costs that willalso continue even if the part is bought©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Make or Buy Example - continued•By this reasoning, the decision to purchase mightcost the company as much as $8.00 + $1.75 + $3.00= $12.75 per unit if it results in idle time in the factoryon the machine that would have been used to makethe part•On the other hand, if the equipment can be used toproduce other components for which the internalprices are less than the corresponding externalquotes, then a buy decision makes good economicsense©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Computer-Aided Process Planning (CAPP)•During the last several decades, there has beenconsiderable interest in automating the processplanning function by computer systems•Shop people knowledgeable in manufacturingprocesses are gradually retiring•An alternative approach to process planning isneeded, and CAPP systems provide this alternative©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

CAPP Systems• Computer-aided process planning systems aredesigned around either of two approaches:1. Retrieval systems2. Generative systems©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Retrieval CAPP Systems•Also known as variant CAPP systems•Based on GT and parts classification and coding•A standard process plan is stored in computer filesfor each part code numberThe standard plans are based on current partroutings in use in the factory, or on an ideal planprepared for each familyFor each new part, the standard plan is edited ifmodifications are needed©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Figure 41.4 Operation of a retrieval type computer-aided processplanning system©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Retrieval CAPP Systems - continued•If the file does not contain a standard process planfor the given code number, the user may search thefile for a similar code numberBy editing the existing process plan, or startingfrom scratch, the user develops a new processplan, which becomes the standard plan for thenew part code•Final step is the process plan formatterThe formatter may call other application programs:determining cutting conditions, calculatingstandard times, or computing cost estimates©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Generative CAPP Systems•Rather than retrieving and editing existing plans froma data base, the process plan is created usingsystematic procedures that might be applied by ahuman planner•In a fully generative CAPP system, the processsequence is planned without human assistance andwithout predefined standard plans•Designing a generative CAPP system is a problem inexpert systems - computer programs capable ofsolving complex problems that normally require ahuman with years of education and experience©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Components of an Expert system fora Generative CAPP System•Knowledge base - the technical knowledge ofmanufacturing and logic used by process plannersmust be captured and coded in a computer program•Computer-compatible part description - thedescription must contain all the pertinent data neededto plan the process sequence•Inference engine - the algorithm that applies theplanning logic and process knowledge contained inthe knowledge base to a given part description©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Benefits of CAPP•Process rationalization and standardization –CAPPleads to more logical and consistent process plansthan when traditional process planning is used•Increased productivity of process planners•Reduced lead time to prepare process plans•Improved legibility over manually written route sheets•CAPP programs can be interfaced with otherapplication programs, such as cost estimating, workstandards, and others©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Problem Solving•Problems arise in manufacturing that requiretechnical staff support beyond what is normallyavailable in the line organization of the productiondepartmentsProviding this technical support is one of theresponsibilities of manufacturing engineeringThe problems are usually specific to the particulartechnologies of the processes performed in theoperating departments and engineering expertiseis often required to solve them©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Continuous ImprovementConstantly searching for and implementing ways toreduce cost, improve quality, and increaseproductivity in manufacturing•Called kaizen by the Japanese•Accomplished one project at a time•May involve a project team whose membershipincludes people from other departments such asproduct design, quality engineering, and productioncontrol©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Typical Continuous ImprovementProject Areas•Cost reduction•Quality improvement•Productivity improvement•Setup time reduction•Cycle time reduction•Manufacturing lead time reduction•Improvement of product design to increaseperformance and customer appeal©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Design Engineering and Manufacturability•Much of the process planning function is pre-emptedby decisions made in product designDecisions on material, part geometry, tolerances,and other design features limit the manufacturingprocesses that can be used•The manufacturing engineer must act as an advisorto the design engineer in matters of manufacturabilitybecause manufacturability matters, not only to theproduction departments but to the design engineer©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

How Design Affects Process Planning –Example•If the product engineer designs an aluminum sandcasting with features that can be achieved only bymachining,Then the process planner must specify sandcasting followed by the necessary machiningoperationsThe manufacturing engineer might advise thedesigner that a plastic molded part would besuperior©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Design for Manufacturingand Assembly (DFM/A)An approach to product design which systematicallyincludes considerations of manufacturability andassemblability in the design•DFM/A includes:Organizational changesDesign principles and guidelines©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Organizational Changes in DFM/A•To implement DFM/A, a company must makechanges in its organizational structure to providecloser interaction and better communication betweendesign and manufacturing personnelOften done by forming project teams consisting ofproduct designers, manufacturing engineers, andother specialties to design a productIn some companies, design engineers must spendsome career time in manufacturing to learn aboutthe problems encountered in making things©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

DFM/A Principles and Guidelines•DFM/A includes principles and guidelines thatindicate how to design a given product for maximummanufacturability•Many of these principles and guidelines are universalRules of thumb that can be applied to nearly anyproduct design situation•In addition, DFM/A includes principles that arespecific to given manufacturing process©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Benefits Typically Cited for DFM/A•Shorter time to bring the product to market•Smoother transition into production•Fewer components in the final product•Easier assembly•Lower costs of production•Higher product quality•Greater customer satisfaction©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Traditional Approach toLaunch a New ProductAn approach to product design that tends to separatedesign and manufacturing engineering•Product design develops the new design, sometimeswith small regard for the manufacturing capabilitiespossessed by the company•There is little interaction between design engineersand manufacturing engineers who might provideadvice on DFM/A©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Concurrent EngineeringAn approach to product design in which companiesattempt to reduce elapsed time required to bring aproduct to market by integrating design engineering,manufacturing engineering, and other functions•Also known as simultaneous engineering•Manufacturing engineering becomes involved early inthe product development cycle•In addition, other functions are also involved, such asfield service, quality engineering, manufacturingdepartments, vendors supplying critical components,and in some cases customers©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Concurrent Engineering (continued)•All of these functions can contribute to a productdesign that performs well functionally, and is alsomanufacturable, assembleable, inspectable, testable,serviceable, maintainable, free of defects, and safeAll viewpoints have been combined to design aproduct of high quality that will deliver customersatisfaction•Through early involvement of all interested parties,the total product development cycle time is reduced©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”

Figure 41.5 –Comparison of: (1) traditional product developmentcycle, (b) product development using concurrent engineering©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e”