注塑成型指南毕业课程设计外文文献翻译Word格式.docx

注塑成型指南毕业课程设计外文文献翻译Word格式.docx

《注塑成型指南毕业课程设计外文文献翻译Word格式.docx》由会员分享，可在线阅读，更多相关《注塑成型指南毕业课程设计外文文献翻译Word格式.docx（68页珍藏版）》请在冰点文库上搜索。

styrenicTPEcompounds（measuredat390°

F（200°

C））.

Toobtaininformationregardingtheviscosityofanindividualgrade,refertotheProductTechnicalDataSheet,availableatorcontactyourGLSrepresentative.

PARTDESIGN

GeneralPartDesignConcepts

WhendesigningaTPEpart,thereareafewgeneralrulestofollow:

•Thepartwallthicknessshouldbeasuniformaspossible.Transitionsfromthicktothinareasshouldbegradualtopreventflowproblems,backfills,andgastraps.

•Thicksectionsshouldbecoredouttominimizeshrinkageandreducepartweight（andcycletime）.

•Radius/filletallsharpcornerstopromoteflowandminimizeno-fillareas.

•Deepunventableblindpocketsorribsshouldbeavoided.

•Avoidthinwallsthatcannotbeblownoffthecoresbyair-assistejection.

•Longdrawswithminimumdraftmayaffecteaseofejection.

FlowLengthandWallThickness

Themaximumachievableflowlengthisdependentonthespecificmaterialselected,thethicknessofthepart,andprocessingconditions.Generally,GLScompoundswillflowmuchfurtherinthinnerwallsthanothertypesofTPEs.Theflowtothicknessratioshouldbe200maximum;

howeverthisisdependentonthematerialandthepartdesign.HighflowGLSTPEcompounds（suchasVersalloy）havebeenusedsuccessfullytofillflowratiosupto400.

Themeasurementofspiralflowoffersacomparativeanalysisofamaterial’sabilitytofillapart.Thespiralflowtestisperformedbyinjectingamaterialintoaspiralmold（similartoaribbonformedintoaspiral）.Thedistancethematerialflowsismeasuredininches.Inthiscase,thespiralflowtestwasconductedusingtwodifferentinjectionspeeds（3in/secand5in/sec）.ThetypicalspiralflowlengthsforthevariousGLSproductfamiliesaresummarizedinTable1.Withspecificcompounds,flowlengthsofupto40inches（at5in/secinjectionspeed）arepossible.

Table1.TypicalSpiralFlowLengthsforGLSCompounds*

Series

Flowlength,in

3in/sec

5in/sec

Dynaflex®

D

13-15

18-20

G

12-22

18-30

Versaflex®

9-16

13-26

*Spiralflowtestsperformedusing0.0625inthicknessand0.375inwidthchannelat400°

F.

Forspiralflowinformationaboutaspecificgradeoradditionaldetailsaboutthespiralflowtestprocedure,pleaserefertotheGLSCorporationTPETipsSheet#7,availableatorbycontactingyourGLSrepresentative.

Undercuts

TheflexibilityandelasticnatureofTPEsallowsfortheincorporationofundercutsintothepartdesign.Becauseoftheirexcellentrecoverycharacteristics,GLScompoundsarecapableofbeingstretchedanddeformed,allowingthemtobepulledfromdeepundercuts（Figure2）.Ifbothinternalandexternalundercutsarepresentonthesamepart,slidesorcoresplitsmaybenecessary.Partswithinternalundercuts（e.g.bulbshapedparts）maybeairejectedfromthecorebyuseofapoppetvalveinthecore.Minorpermanentelongation（3%-8%）duetodeformationmayoccurduringejection.

Figure2.AnexampleofTPEpartswithlargeundercuts.

GateandKnitLineLocations

Theproductengineershouldindicatetheareasofthepartthatarecosmeticandthosethatarefunctionalandincludethisinformationonthedrawing.Thiswillhelpthemolddesignertodeterminetheallowablegateandknitlinelocations.

Anisotropy

Thermoplasticmaterialsthathavedifferentpropertiesintheflowdirectionversusthecross-flowdirection（90º

perpendiculartotheflowdirection）arecharacterizedas“anisotropic”materials.Propertiesthatmaybeaffectedareshrinkageandtensileproperties.Anisotropyiscausedwhenthepolymerchainsorientinthedirectionofflow,whichleadstohigherphysicalpropertiesintheflowdirection.Wallthickness,injectionspeed,melttemperatureandmoldtemperatureareafewvariablesthataffectanisotropy.Dependingontheprocessingconditionsandmolddesign,mostGLSstyrenicTPEcompoundsexhibitadegreeofanisotropy.

Shrinkage

Duetotheiranisotropicnature,GLSstyrenicTPEcompoundsshrinkmoreintheflowdirectionthaninthecross-flowdirection.Generally,SEBScompoundshavehighershrinkageandaremoreanisotropicthanSBScompounds.TypicalshrinkagevaluesforSEBS-basedcompoundsare1.3%-2.5%,whereasthoseforSBSbasedcompoundsare0.3%-0.5%.SofterSEBScompounds（below30ShoreA）willshrinkmorethanharder6materials.Somegrades,suchasDynaflexG7700,G7800,andG7900Seriescontainfiller,whichreducestheirshrinkage.

TheshrinkagevaluesreportedbyGLSaredeterminedusinga0.125”thickplaque.Itshouldbenotedthatshrinkageisnotanexactnumber,butarangevalue.Thisrangecanbeaffectedbythepartwallthickness,melttemperature,moldtemperature,injectionspeed,hold/packpressuresandalsothetimebetweenmoldingandmeasuring.Asaresult,prototypingisstronglyrecommendedforpartswithclosetolerancestobetterquantifytherealisticshrinkageofaspecificgradeofmaterialinaspecificapplication.

Forshrinkagevaluesforspecificgrades,pleaserefertotheproductTechnicalDataSheet,availableatorbycontactingyourGLSrepresentative.

MOLDDESIGN

TypesofMolds

GLSSBCcompoundscanbemoldedintwo-andthree-platemolds.BothconventionalandhotrunnertooldesignshavebeenusedwithGLScompounds.Self-insulatinghotrunnertooldesignsarenotrecommendedduetothepotentialformaterialdegradationinthestagnationzones.Two-shotmoldsandinsertmoldscanalsobeused.Ifafamilymoldisrequired,thecavityvolumesshouldbesimilar,otherwiseoverpackingandflashingofthesmallercavitymayoccur.

SteelSelection

GLSstyrenicTPEsaregenerallynon-abrasiveandnon-corrosive.Theselectionoftoolsteelwilldependonthequantityandqualityofpartstobeproduced.Forhighvolumeproduction,theinitialexpenseofqualitytoolingisasoundinvestment.

Awidevarietyoftoolsteelsareavailableforinjectionmoldconstruction.Table2liststhepropertiesofcommontoolsteelsandthetypicalmoldcomponentsforwhichtheyareused.Softmetals,suchasaluminumandberylliumcopper,canbeusedforprototypepartsorshortproductionrunsupto10,000parts.

Table2.TypicalToolSteelforInjectionMoldConstruction

SteelType

SteelProperties

MoldComponent

P-20

Pre-hardened,machineswell,highcarbon,general-purposesteel.Disadvantage:

Mayrustifimproperlystored.

Moldbases,ejectorplates,andsomecavities（ifnickelorchromeplatedtopreventrust）.

H-13

Goodgeneralpurposetoolsteel.Canbepolishedorheat-treated.Bettercorrosionresistance.

Cavityplatesandcoreplates.

S-7

Goodhighhardness,improvedtoughness,general-purposetoolsteel.

Machineswell,shockresistant,polisheswell.Disadvantage:

Highercost.

Cavityplates,coreplatesandlaminates,aswellasthinwallsections.

A-2

Goodhightoughnesstoolsteel.Heat-treatsandpolisheswell.

Ejectorpins,ejectorsleeves,andejectorblades.

D-2

Veryhard,highwearcharacteristics,highvanadiumcontent,somewhatbrittle.Disadvantage:

Difficulttomachine.

Gateblocks,gibeplatestopreventgalling,gateblockstopreventwear.

420SS

Toughcorrosionresistantmaterial.

Heat-treatsandpolisheswell.

Disadvantage:

Highcost.

Cavityblocks,ejectorpins,sleeves,etc.

Somepartdesignsmaybenefitfromtheuseofhigherthermalconductivitymaterialssuchasberylliumcopper.Thismaterialislessdurablethansteelandmayhoborwearfasterthansteelifusedattheparting-line.Berylliumcoppercanbeusedforinserts,slidesorcorestoincreaseheattransferratesandreducecycletimes.Incaseswherethereisalongdrawcore,afountain-typebubblermaybebeneficial.

MoldSurfaceTreatment,FinishingandTexturing

MostGLSmaterialsreplicatethemoldsurfacefairlywell.Toproduceaglossysurface,apolishedmoldisrequiredandanunfilledgradeshouldbeused.Ahighlypolishedtoolandatransparentmaterialarerequiredtoproduceapartwithgoodclarity.Ifamattefinishsimilartothatofathermosetrubberisrequired,aroughermoldtextureshouldbeused（oraGLSproductsuchasGLSVersalloyTPValloys,whichnaturallyproduceamattesurface）.Ingeneral,anEDMsurfacewillproduceagoodtextureandmayimprovereleasefromthetoolduringpartejection.Mattesurfacescanalsohelptohideanyflowmarksorothersurfacedefects.Vaporhoning,sandorbeadblastingandchemicaletchingarealsousedtoproducetexturedsurfaceswithvaryingdegreesofglossandappearance.Toaidinrelease,thecavityorcoremaybecoatedwithareleasecoatingsuchasPTFEimpregnatednickelafterithasbeengivenasandblastorEDMfinish.

SprueandSpruePullerDesign

Thesprueshouldhavesufficientdraft,from1º

to3º

tominimizedragandspruesticking.Longerspruesmayrequiremoretaper（3°

-5°

）,a