Injection-Molding-&-Advanced-Process-Control国外挤压机2

1-BasMInjectionMolding&AdvancedProcessControlInjectionMolding&AdvancedProcessControlSPEAutomotiveTPOGlobalConference20092-BasMPolymerBasics3-BasMMaterialselectionispartofthedesignprocessandcandirectlycausefailureAkeyelementinasuccessfulplasticpartprogramistheselectionoftheappropriatematerialfortheapplication.Theprocessofmaterialselectioniscomplicatedbythefactthatthereareliterallythousandsofpolymers,blends,alloys,andcompoundsavailable.Theselectionprocesscanbesimplifiedbycomprehending:TheperformancerequirementsofthepartHowmaterialsareclassifiedTestingmethods4-BasMTransferSystemSiloSiloEsterifier1°Esterifier2°HighPolymerizerLowPolymerizerPumpManifoldExtrusionPolymer:FromtheGreekPolymeaningmany,andMeros(mer),meaningpart(s)ChemicalComposition:ExamplePolyethylene:Crackcrudeoiltoethylenethenpolymerized(linkedtogether)toform500-1,000,000ethyleneunitsPOLYMERIZATIONPROCESSFeedstock:CrudeOilNaturalGasAgriculture5-BasMPolymer:FromtheGreekPolymeaningmany,andMeros(mer),meaningpart(s)ChemicalComposition:ExamplePolyethylene:Crackcrudeoiltoethylenethenpolymerized(linkedtogether)toform500-1,000,000ethyleneunitsKeyPoints:PolymerscanhavethesamecarbonbackbonebutdrasticallydifferentpropertiesPolymerswithOxygen(O),Nitrogen(N),Chlorine(CI),Bromine(Br),orFluorine(F)probablyhavetobedriedTimeandspacedonotallowustorevieweachpolymercompositionanditsproperties.AnexcellentsourceforbasicpolymerdescriptionscanbefoundinthefirstpagesoftheyearlyModernPlasticsEncyclopedia.6-BasMChainLengthsAtroomtemperatureC1=Methane,agasC6=Hexane,aliquidC17=KeroseneC50=WaxC500-1,000,000=PolyethyleneForstrengthLongmoleculesarepreferredForprocessabilityShortmoleculesarepreferredEasyflowLowviscosityTransmitspressuremorehydrostaticallyLongmoleculesDifficulttoflowHighviscosityViscositychangesdramaticallywithchangesinflowrateDynamic:flowrateduringfillingStatic:flowrateduringpackandholdLargestaticpressurelossesalongtheflowpathResinmanufacturingmustcompromise/balancechainlengthvs.strengthvs.flow.Mostpolymersthatfindcommercialuseasplasticsorrubbershavemolecularweightsbetween10,000and1,000,000.7-BasMMolecularWeight(Mw):MolecularWeight=(MolecularWeightofRepeatUnitxNumberofUnits)Inpractice,whenpolymersaremade,chainsorthenumberofunitslinkedtogethervariesWithinthesamepolymerfamilymolecularweightisameasureofmolecularlength:HighMolecularWeight=LongMolecules=StrongerLowMolecularWeight=ShortMolecules=Weaker8-BasMMolecularLengthPolymersaremixturesofvariouslengthmoleculesNotallchainsarethesamelengthMolecularweightdistribution9-BasMBatchtoBatchVariationsCauseChangesinViscosityEffectsofMolecularWeightGenerallyasmolecularweightincreases,physicalpropertiesincreaseattheexpenseofprocessingeaseShortchains-easyflowLongchains-difficulttoflow10-BasMPolymerchainsarestrongAramidefibers(flackjackets,tires)ChainscanbebrokenbyimproperprocessingToomuchheatToomuchtimeatelevatedtemperatures(dryingandmelt)ToomuchshearforcePresenceofachain-breakingchemical(e.g.,water)PolyesterPolycarbonateNylonProperdryingisessentialforthesematerialsPolymerChainDegradation11-BasMDegradationImproperprocessingcandegradepolymerchainsandprovidepoorpartperformanceChaindegradationwillprovidearegrindthatiseasierflowing(lowerviscosity)Shortermolecules=poorstrengthHowcanthisbedetected?12-BasMPolymersPlasticsPlastics=Polymer+AdditivesAdditives:Impactmodifiers(rubber)FillersNucleatingagentsFlameretardantsMoldreleaseagentsAntioxidantsWettingagentsPlasticizersFiberreinforcementsHeatstabilizersLubricantsAntistaticagentsColoringagentsSlipaids13-BasMAdditiveDegradation:AdditivechainsizeissmallrelativetothepolymerMaybecomevolatileduringprocessingwhichcanresultin:Accumulationinvents,moldsurfaces,etc.Changeinphysicalproperties(oftenanincrease)Stifferflow(higherviscosityplastic)ChangeinAdditiveContentisaPrimeDifferenceBetweenVirginandEarlyGenerationsofRegrind.Materialisgoingtovaryfolks–that'snoexcuse!14-BasMPolymerMorphologyTwofamiliesofthermoplasticsAmorphousSemi-crystallineRandomStructureBroadMeltingPointOftenSolventSensitivePoorFatigue/wearLowShrinkNoMolecularCuddlingMoreForgivingondimensionalControlOrderedStructureSharpMeltingPointSolventResistantExcellentFatigueWearHighShrinkHighMolecularCuddlingProblematicondimensionalControl15-BasMCoolingandCrystallinityExtremelyimportantforsemi-crystallinematerialsCrystalsarenon-existentabovemeltingtemperatureLowmoldtemp,fastercooling,smaller/lesscrystals,lessshrinkage,butmaynotbesuitableforapplicationHighmoldtemp,slowercooling,larger/morecrystals,moreshrinkageMoldandMelttemperaturesarecriticaltomaintaindimensionaltolerances16-APTDecoupledMoldingSMStrategies17-AFTrain1.JPGTrain2afillpackonly.jpgTrain2.jpgInjectionMoldingApproachesTraditionalMolding:TheoriginalmethodofmoldingFillandpackonfirststageUseonlyenoughfirststagepressuretopackthemoldDECOUPLEDMOLDINGSM:UseabundantfirststagepressureSeparatethefillingorvelocityphaseofmoldingfromthepackingorpressurizationphase18-AFTrain2afillpackonly.jpgDefini