Bulk Deformation Processes - "HablumminaAllah wa …

1 bulk Deformation ProcessesBachelor of Industrial Technology Management with HonoursSemester I Session 2013/2014 TOPIC OUTLINE WhatisBulkDeformation? ClassificationofBulkDeformationProcesses Typesofbulkdeformationprocesses Forging Extrusion Drawing , OUTCOMESWhat Is bulk Deformation ? Operationsthatinduceshapechangesonthemet alworkpiecebyplasticdeformationunderforc esappliedbyvarioustoolsanddies. Startingforms:cylindricalbarsandbillets, rectangularbilletsandslabs,andsimilarsha pes. Theseprocessesworkbystressingmetalsuffic ientlytocauseplasticflowintodesiredshape . Thecross-sectionofworkpiecechangeswithou tvolumechange. Is bulk Deformation ?Classification Of bulk Deformation ProcessesAdvantagesDisadvantagesBetter accuracyHigher forces and powerBetter surface finishLimitations to the amount of formingHigh strengthAdditional annealing for some material is requiredHardness of the partSome material are not capable of cold workingNo heating is requiredCold Working Metal forming performed at room temperatureClassification Of bulk Deformation ProcessesAdvantagesDisadvantagesLower forces and powerSome investment in furnaces is neededMorecomplex part shapesNo annealing is requiredWarm Working Metal forming performed at temperature above the room temperature but below the recrystallization condition Classification Of bulk Deformation ProcessesAdvantagesDisadvantagesBig amount of forming is possibleLower accuracy and

2 Surface finishLower forces and power are requiredHigher production costForming of materials with low ductility Shorter tool lifeNo hardening work -no additional annealing is requiredHot Working Involves Deformation of pre-heated material at temperature above the recrystallization temperature Types Of bulk Deformation ProcessesForging Thediameterofawireorbarisreducedbypullin gitthroughadieopening(bardrawing)oraseri esofdieopenings(wiredrawing).Rolling Of bulk Deformation Processes Forging Processinwhichtheworkiscompressedbetween twodies/mould Somefinishingoperationsarenecessary Diesandequipmentcostsarehigh Involvesmoderatetohighlaborcosts Requiremoderatetohighoperatorskills Threetypesofforging:1. Open-dieforging2. Impression-dieforging3. Flash-lessforgingForgingOpen-dieforging Knownasupsetting,itinvolvescompressionof aworkbetweentwoflatdiesorplatens.

3 And inexpensive range of part strength for small to simple to hold close to final shape production forging of a multi diameter Workpiecetakestheshapeofdiecavitywhilebe ingforgedbetweentwoshapeddies. Carriedoutatelevatedtemperaturesforenhan cedductilityofthemetalsandtolowertheforc es. (from bottom to top) in the formation of a crankshaft by hot impression-die forgingClosed-die/Flashlessforging Workmaterialiscompletelysurroundedbythed iecavityduringcompressionandnoflashisfor med. volume must equal the space in the die cavity to a very close Workisforcedtoflowthroughadieopeningtopr oduceadesiredcross-sectionalshape. Usedtoproducelongpartsofholloworsoliduni formcross-sections. Productsthencuttothedesiredlengths. Aluminium,copper,steel,magnesiumandplast icsaremostsuitableforextrusion.

4 Moderatetohighdieandequipmentcost. Lowtomoderatelaborcostsandoperatorskill. Dependingontheductilityofthematerialused , , , , Carriedoutatelevatedtemperaturesin2 Diewearcanbeexcessiveandcoolingofthehotb illetinthechambercanbeaproblem,whichresu ltsinhighlynon-uniformdeformation. Toreducecoolingofthebilletandtoprolongdi elife, Metalsworkedpossesstheplasticitynecessar y(highdegreeofductility)forsuccessfulfor mingwithoutheatingthem. Donetoimprovethephysicalpropertiesofamet alandtoproduceafinishedpart. Itisfast, Billetisplacedinthecontainerandaramtowar dsthediepushesit. Metalslidesalongthewallsofthecontaineran disforcedtoflowthroughdieopening. Attheendoftheextrudingoperation,asmallpi eceofmetal,calledbutt-endscrap, Dieismountedontheendofahollowramandenter sthecontainer. Theouterendofcontainerbeingclosedbyaclos ureplate.

5 Astheramtravels, Productionoflongrod,wireandtubingwithrou ndorvariouscross-sectionthanextrusionsby pullingthematerialthroughadieopening. Similartoextrusionexceptworkispulledthro ughdieindrawing(itispushedthroughinextru sion).Drawing Practice: Usuallyperformedascoldworking Mostfrequentlyusedforroundcross-sections Products: Wire:electricalwire;wirestockforfences,c oathangersandshoppingcarts Rodstock:nails,screws,rivets,andsprings Barstock:metalbarsformachining,forgingan dotherprocessesWireDrawingvsBarDrawing Differenceisthestocksize: Bardrawing-largediameterbarandrodstock ( )arepossibleDrawingRolling Processofreducingthethicknessorchangingt hecross-sectionofawork-piecebycompressiv eforcesexertedbyapairofrotatingrolls. Products:plates&sheets-platesareusedfors tructuralapplicationslikebridges,shipsan dnuclearvesselswhilesheets(generally6mmo rlessinthickness)areusedforautomotive,be veragecans,office& Thepreheatedat1200 squarecross-sectionof150 40 40/40mmormoreisrolledfromabloom types of Workisdeformedbyagradualreductionintoaco ntouredcrosssection(I-beams,L-beams,U-ch annels,rails,round,squarebarsandrods,etc .)

6 Gearrollingissimilartothreadrollingwitht hreegears(tools)thatformthegearprofileon thework.