Process Selection Manufacturing Processes
Process SelectionManufacturing processes Processes and their attributes Screening by attributes Selecting shape-forming processes Shaping Selecting joining processes Joining Selecting surface-treatment processes Surface treatment Case study demos The text book classified manufacturing processes into three broadcategories Each has many sub-categories, which may then be further subdividedinto individual processes Many processes are used in combination with others Manufacturing process selection involves identifying which willwork best for a particular applicationMore info: “Materials Selection in Mechanical Design”, Chapters 7 and 8ME 474-674 Winter 2008ME 474-674 Winter 2008Slides 7 -1Examples of processesData organization: the PROCESS tableShapingBlow mouldingSand castingSlides 7 ldingInjectionCompositeRTMPowderBlowRapid lassEach family hasattributes that differ.Difficult on-- pecificgeneral----generalgeneralProcess recordsFusion weldingInduction hardeningME 474-674 Winter 2008ME 474-674 Winter 2008Slides 7 -3Shape classificationSlides 7 -4Structured data for injection molding*Injection molding (Thermoplastics)Some processes can make only simple shapes, others, complex shapes. INJECTIONMOULDING of thermoplastics is the equivalent of pressure die casting of metals. Molten polymeris injected under high pressure into a cold steel mould. The polymer solidifies under pressure and the molding isthen ejected.ShapeCircular PrismNon-circular PrismSolid 3-DHollow 3-DEconomic AttributesTrueTrueTrueTrueEconomic batch sizeRelative tooling costRelative equipment costPhysical attributesMass rangeRoughnessSection thicknessTolerance0.010.2 0.4 0.1 -251.66.31Process characteristicsDiscretePrototypingzWire drawing, extrusion,rolling, shape rolling:prismatic shapesz Stamping, folding,spinning, deep drawing:sheet shapesME 474-674 Winter 2008zInjection molding is used .Slides 7 -5Cost modelingRelative cost indexfx links to materialsTrueFalseTypical usesCasting, molding,powder methods:3-D shapeskgµmmmmm1e 004 - 1e 006highhigh*Using the CES EduPack Level 2 DBKey physical factors in choosinga shaping process(economics always important)ME 474-674 Winter 2008Slides 7 -61
Unstructured data for injection molding*The process. Most small, complex plastic parts you pick up –children’s toys, CD cases, telephones – are injection moulded.Injection moulding of thermoplastics is the equivalent of pressuredie casting of metals. Molten polymer is injected under highpressure into a cold steel mould. The polymer solidifies underpressure and the moulding is then ejected.Various types of injection moulding machines exist, but the mostcommon in use today is the reciprocating screw machine, shownschematically here. Polymer granules are fed into a spiral presslike a heated meat-mincer where they mix and soften to a puttylike goo that can be forced through one or more feed-channels(“sprues”) into the die.Finding information with CESFileEditViewSelectToolsG ranular P olym erM ouldToolbarNozzleBrowseSelectSearchPrintSearch webCylinderTable:Table: ProcessUniverseProcessUniverseH eaterS crewSubset:Subset: EduEdu LevelLevel 22Find what?SLSRTMWhich table?ProcessesN o .8 -C M Y K-5 /0 1ProcessUniverse Designguidelines. Injection moulding is the best way to mass-produce small, precise, plastic parts with complex shapes.The surface finish is good; texture and pattern can be moulded in, and fine detail reproduces well. The only finishing operationis the removal of the sprue. Theeconomics. Capital cost are medium to high; tooling costs are high, making injection moulding economic only for largebatch-sizes (typically 5000 to 1 million). Production rate can be high particularly for small mouldings. Multi-cavity moulds areoften used. The process is used almost exclusively for large volume production. Prototype mouldings can be made usingcheaper single cavity moulds of cheaper materials. Quality can be high but may be traded off against production rate. Processmay also be used with thermosets and rubbers. Joining Shaping Surface treatment Typicaluses. The applications, of great variety, include: housings, containers, covers, knobs, tool handles, plumbingfittings, lenses, etc. Theenvironment. Thermoplastic sprues can be recycled. Extraction may be required for volatile fumes. Significant dustexposures may occur in the formulation of the resins. Thermostatic controller malfunctions can be extremely hazardous.*Using the CES EduPack Level 2 DBME 474-674 Winter 2008ME 474-674 Winter 2008Slides 7 -7Process SelectionSlides 7 -8Selection by series of screening stages Like materials selection, process selection also has the same 4 basic steps Once a material is selected, it becomes one of the constraints in . Selection dataHybridMetalPolymerEduEdu LevelLevel 2:2: ProcessesProcesses-- shapingshapingFerrousNon-ferrousShapeStep 1 Translation: express design requirements as constraints & objectives2. Selection StagesGraphStep 2 Screening: eliminate processes that cannot do the jobLimitCircular prismaticNon-circular prismaticFlat sheetetcTreePhysical attributesStep 3 Ranking: find the processes that do the job most cheaplyMass rangeToleranceRoughnessResultsX out of 60 passStep 4 Supporting information: explore pedigrees of top-ranked candidates0.20.3 kg0.5 mm100 μmProcess 1Process 3Process 4Process 5ME 474-674 Winter 2008 .Slides 7 -9Example of the Translation stepB1 B B2Batch size BProcess 2Because there are thousands of variants of processes,supporting information plays a particularly important roleME 474-674 Winter 2008Slides 7 -10Spark-plug insulator: translationExample: Casing for a capacitance pressure sensor for use as a traffic sensorInsulatorTranslation of design requirementsThe sensor lies across the road, coveredby a rubber mat. Vehicle pressure deflectstop face, changing capacitance between topface and copper conducting strip.Body shellFunctionConstraintsObjectivesFree variableInsulatorFunction Material class Shape classMass3-D, hollow0.05 kgDesign requirements Section3 - 5 mmMake 2,000,000 insulatorsfrom alumina with given Tolerance 0.5 mmRoughness Batch size 100 μm 2,000,000CentralelectrodeCasing for road-pressure sensorMaterial: Al alloyShape: non-circular prismaticMinimum section: 2 0.025 mmMinimize cost shape dimensions tolerance and surface roughnessConstraints Free variableAluminaChoice of processChoice of processME 474-674 Winter 2008Slides 7 -11ME 474-674 Winter 2008Slides 7 -122
Rank on Processes based on batch sizeSpark-plug insulator: screening1BodyshellSelect Level 2: Shaping sW-carbide1e8Powder injection moldingPressing and sintering1e7DesiredBatch SizePhysical attributes Material class Shape class MassSection0.05 kg3 – 5 mm Tolerance 0.5 mm RoughnessBatch size 100 μm 2,000,000 00 μ m0.04Mass range3-D, hollowRange of sect. thickness33Economic attributesEconomic batch size2e6Economic batch size , 3 DME 474-674 Winter 2008100ME 474-674 Winter 2008Slides 7 -13The selection: two shaping processesData organization: joining ningProcessesSolderWeldingGasFastenersArcShapinge -beam .SurfacetreatmentPowder injection moldingPowder pressing and sinteringJointgeometryME 474-674 Winter 2008Slides 7 -14 Lap Butt Sleeve Scarf ocumentationRelativeDocumentationRelativecostcost ionME 474-674 Winter 2008Slides 7 -15A joining record*Slides 7 -16Selection of Joining ProcessesGas Tungsten Arc (TIG)Tungsten inert-gas (TIG) welding, the third of the Big Three (the othersare MMA and MIG) is the cleanest and most precise, but also the mostexpensive. In one regard it is very like MIG welding: an arc is struckbetween a non-consumable tungsten electrode and the work piece,shielded by inert gas (argon, helium, carbon dioxide) to protect themolten metal from contamination. But, in this case, the tungstenelectrode is not consumed because of its extremely high meltingtemperature. Filler material is supplied separately as wire or rod. TIGwelding works well with thin sheet and can be used manually, but iseasily automated.Joining -- the most important criteria are:zThe material(s) to be joinedzThe geometry of the jointApply these first,then add other constraintsJoint ialsFerrous metalsTrueEconomic AttributesPhysical AttributesComponent sizeWatertight/airtightDemountableSection thicknessnon-restrictedTrueFalse0.7 - 8 mmRelative tooling costRelative equipment costLabor intensitylowmediumlow links to materialsTypical usesTIG welding is used .Documentation*Using the CES EduPack Level 1 DBKey physical factors inchoosing a joining processME 474-674 Winter 2008Slides 7 -17ME 474-674 Winter 2008Slides 7 -183
A surface-treatment record*Data organization: Surface treatmentKingdomFamilyClassMemberShapingHeat treatPaint/printSurfacetreatmentTake a medium or high carbon steel -- cheap, easily formed and machined -and flash its surface temperature up into the austenitic phase-region, fromwhich it is rapidly cooled from a gas or liquid jet, giving a martensitic surfacelayer. The result is a tough body with a hard, wear and fatigue resistant,surface skin. Both processes allow the surface of carbon steels to behardened with minimum distortion or oxidation. In induction hardening, a highfrequency (up to 50kHz) electromagnetic field induces eddy-currents in thesurface of the work-piece, locally heating it; the depth of hardening dependson the frequency. In flame hardening, heat is applied instead by hightemperature gas burners, followed, as before, by rapid tion and flame hardeningAttributesCoatElectroplateAnodizePowder coatPolishTexture mentationFunction of treatmentProcess recordsFatigue resistanceFriction controlWear resistanceHardnessEconomic AttributesRelative tooling costRelative equipment costLabor intensityPhysical AttributesFunction oftreatment Increased hardness Thermal insulation Wear resistance Electrical insulation Fatigue resistance Color Corrosion resistance Texture Oxidation resistanceCurved surface coverageCoating thicknessProcessing temperatureSurface hardnessDocumentationVery good300 - 3e 003 µm727 - 794K420 - 720Vickers links to materialsTypical usesInduction hardening is used . Decoration .ME 474-674 Winter 2008lowmediumlowSlides 7 -19Key physical factors in choosing asurface treatmentME 474-674 Winter 2008*Using the CES EduPack Level 2 DBSelection of Surface Treatment ProcessesSlides 7 -20The main points Processes can be organized into a tree structure containing records forstructured data and supporting informationSurface treatment -- the most important criteria are:zThe purpose of the treatmentzThe material to which it will be appliedApply these first,then add other constraints The structure allows easy searching for process data Select first on primary constraints Shaping:material, shape, and batch size Joining:material(s) and joint geometry Surface treatment: material and function of treatment Then add secondary constraints as needed.zME 474-674 Winter 2008Documentation in CES, and http://matdata.netME 474-674 Winter 2008Slides 7 -21The Process – Material matrix A given process can shape, or join, or finish some materials but notothers. Process – Material charts have a red dot to indicate that the pair arecompatible. Processes that cannot shape the material of choice are non-starters.ME 474-674 Winter 2008Slides 7 -22The Process – Material matrixFigure 7.16Slides 7 -23ME 474-674 Winter 2008Slides 7 -244
The Process – Shape matrixShape classificationSome processes can make only simple shapes, others, complex shapes. Shape is the most difficult attribute to characterize. Many processes involve rotation or translation of a tool or of the work-piece.These processes make parts that have axial symmetry, or translationalsymmetry. Turning creates axisymmetric (or circular) shapes; Extrusion, drawing and rolling make prismatic shapes, both circular andnon-circular. Sheet-forming processes make flat shapes (stamping) or dished shapes (deepdrawing, bending). Certain processes can make 3-dimensional shapes, and among these somecan make hollow shapes whereas others cannot. The process-shape matrix displays the links between the two. If the processcannot make the desired shape, it may be possible to combine it with asecondary process to give a process-chain that adds the additional features:casting followed by machining is an obvious example.ME 474-674 Winter 2008Figure 7.18zWire drawing, extrusion,rolling, shape rolling:prismatic shapesCasting, molding,powder methods:3-D shapesSlides 7 -26The Process – Mass - range chartFigure 7.17 The bar-chart on the next page shows the typical mass-range of componentsthat each processes can make. Large components can be built up by joining smaller ones. Therefore theranges associated with joining are also shown. In applying a constraint on mass, we seek single shaping-processes orshaping-joining combinations capable of making ia part and reject those thatcannot.ME 474-674 Winter 2008Slides 7 -27The Process – Mass - range chartSlides 7 -28The Process – Section thickness chartFigure 7.19 The bar-chart on the next page allows selection to meet constraints on sectionthickness. Surface tension and heat-flow limit the minimum section of gravity castshapes. ME 474-674 Winter 2008zME 474-674 Winter 2008Slides 7 -25The Process – Shape matrixME 474-674 Winter 2008z Stamping, folding,spinning, deep drawing:sheet shapesSlides 7 -29The range can be extended by applying a pressure or by pre-heating themold, but there remain definite lower limits for the section thickness. Limits on rolling and forging-pressures set a lower limit on thicknessachievable by deformation processing. Powder-forming methods are more limited in the section thicknesses they cancreate, but they may be the only ones available for ceramics and very hardmetals that cannot be shaped in other ways. The section thicknesses obtained by polymer-forming methods – injectionmolding, pressing, blow-molding, etc – depend on the viscosity of the polymer;fillers increase viscosity, further limiting the thinness of sections. Special techniques, which include electro-forming, plasma-spraying andvarious vapor – deposition methods, allow very slender shapes.ME 474-674 Winter 2008Slides 7 -305
The Process – Section thickness chartThe Process – Tolerance chart NoFigure 7.20process can shape a part exactly to a specified dimension. Some deviation Δx from a desired dimension x is permitted This is referred to as the tolerance, T, and is specified as mm, or asx 100 0.1mmor1x 50 00.05mmME 474-674 Winter 2008ME 474-674 Winter 2008Slides 7 -31The Process – Tolerance chartThe Process – Surface roughness chartFigure 7.21 The surface roughness R, is measured by the root-mean-squareamplitude of the irregularities on the surface. It is specified as ME 474-674 Winter 2008 R 100μm (the rough surface of a sand casting) or R 0.01μm (a highly polished surface).The bar chart on the next page allows selection to achieve a givensurface roughness.ME 474-674 Winter 2008Slides 7 -33The Process – Surface roughness chartSlides 7 -34The Process – Economic batch-size chart Process cost depends on a large number of independent variables. Theinfluence of many of the inputs to the cost of a process are captured bya single attribute: the economic batch size. A process with an economic batch size with the range B1 – B2 is onethat is found by experience to be competitive in cost when the outputlies in that range.Figure 7.22ME 474-674 Winter 2008Slides 7 -32Slides 7 -35ME 474-674 Winter 2008Slides 7 -366
The Process – Economic batch-size chartFigure 7.24ME 474-674 Winter 2008Slides 7 -377
Manufacturing processes The text book classified manufacturing processes into three broad categories Shaping Joining Surface treatment Each has many sub-categories, which may then be further subdivided into individual processes Many processes are used in combination with others Manufacturing p
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Selection Nr.: 0 O Price set to zero Selection Nr.: 5 O Fast up Fast Increase of price or column Selection Nr.: 6 O Fast down Fast Decrease of price or column Selection Nr.: # O Copy function Copy price on next column Selection Nr.: * O Slave selection Request for slave selection Password 4 -2-3-1-4 Entry by selection button 4 key 4
There are four chief manufacturing processes i.e. (1) welding, (2) casting, (3) machining and (4) forming. Selection of suitable manufacturing process for a product/component is determined by the following factors: i. Complexity of geometry of the component ii. Number of units to be produced iii.
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selection. 18. Is the selection that led to the development of wolves and coyotes an example of natural selection or artificial selection? Explain your choice. 19. Refer to Model 1. Is the selection leading to changes in the E. coli variants natural or artificial selection? Explain your choice. 20.
Next we detail the project selection process, discussing the various types of selection models commonly used, the database needed for selection, and the management of risk. 2.2 PROJECT SELECTION AND CRITERIA OF CHOICE Project selection is the process
1.Kalpakjian and Schmid, Manufacturing processes for engineering materials -Pearson India, 5th Edition 2014. Reference Books: 1. Mikell P. Groover, Fundamentals of Modern Manufacturing: Materials, Processes, and Systems John Wiley & Sons Inc., 4th Edition, 2008. 2. Degarmo, Black &Kohser, Materials and Processes in
evaluation of English Pronunciation and Phonetics for Communication (second edition) and English Phonology (second . textbook is English Phonology written and edited by Wang Wenzhen, which was first published by Shanghai Foreign Language Educational Press in 1999. It was modified and republished in 2008 and also came with a CD. 4 Polyglossia Volume 25, October 2013 2.4 Procedure and Data .
