复合材料注塑成型中英文对照外文翻译文献.docx
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复合材料注塑成型中英文对照外文翻译文献
复合材料注塑成型中英文对照外文翻译文献
(文档含英文原文和中文翻译)
Anexperimentalstudyofthewater-assistedinjectionmoldingofglassfiberfilledpoly-butylene-terephthalate(PBT)composites
Abstract:
Thepurposeofthisreportwastoexperimentallystudythewater-assistedinjectionmoldingprocessofpoly-butylene-terephthalate(PBT)composites.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedvirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,andmechanicalpropertytestswereperformedontheseparts.X-raydiffraction(XRD)wasalsousedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.Itwasfoundthatthemeltfillpressure,melttemperature,andshortshotsizewerethedominantparametersaffectingwaterpenetrationbehavior.Materialatthemold-sideexhibitedahigherdegreeofcrystallinitythanthatatthewater-side.Partsmoldedbygasalsoshowedahigherdegreeofcrystallinitythanthosemoldedbywater.Furthermore,theglassfibersnearthesurfaceofmoldedpartswerefoundtobeorientedmostlyintheflowdirection,butorientedsubstantiallymoreperpendiculartotheflowdirectionwithincreasingdistancefromtheskinsurface.
Keywords:
Waterassistedinjectionmolding;Glassfiberreinforcedpoly-butylene-terephthalate(PBT)composites;Processingparameters;B.Mechanicalproperties;Crystallinity;A.Polymermatrixcomposites;
1.Introduction
Water-assistedinjectionmoldingtechnology[1]hasproveditselfabreakthroughinthemanufactureofplasticpartsduetoitslightweight,fastercycletime,andrelativelylowerresincostperpart.Inthewater-assistedinjectionmoldingprocess,themoldcavityispartiallyfilledwiththepolymermeltfollowedbytheinjectionofwaterintothecoreofthepolymermelt.Aschematicdiagramofthewater-assistedinjectionmoldingprocessisillustratedinFig.1.Water-assistedinjectionmoldingcanproducepartsincorporatingboththickandthinsectionswithlessshrink-ageandwarpageandwithabettersurfacefinish,butwithashortercycletime.Thewater-assistedinjectionmoldingprocesscanalsoenablegreaterfreedomofdesign,materialsavings,weightreduction,andcostsavingsintermsoftoolingandpresscapacityrequirements[2–4].Typicalapplicationsincluderodsandtubes,andlargesheet-likestructuralpartswithabuilt-inwaterchannelnetwork.Ontheotherhand,despitetheadvantagesassociatedwiththeprocess,themoldingwindowandprocesscontrolaremorecriticalanddifficultsinceadditionalprocessingparametersareinvolved.Watermayalsocorrodethesteelmold,andsomematerialsincludingthermoplasticcompositesaredifficulttomoldsuccessfully.Theremovalofwateraftermoldingisalsoachallengeforthisnoveltechnology.Table1liststheadvantagesandlimitationsofwater-assistedinjectionmoldingtechnology.
Fig.1.Schematicdiagramofwater-assistedinjectionmoldingprocess.
Waterassistedinjectionmoldinghasadvantagesoveritsbetterknowncompetitorprocess,gasassistedinjectionmolding[5],becauseitincorporatesashortercycletimetosuccessfullymoldapartduetothehighercoolingcapacityofwaterduringthemoldingprocess.Theincompressibility,
lowcost,andeaseofrecyclingthewatermakesitanidealmediumfortheprocess.Sincewaterdoesnotdissolveanddiffuseintothepolymermeltsduringthemoldingprocess,theinternalfoamingphenomenon[6]thatusuallyoccursingas-assistedinjectionmoldedpartscanbeeliminated.Inaddition,waterassistedinjectionmoldingprovidesabettercapabilityofmoldinglargerpartswithasmallresidualwallthickness.Table2listsacomparisonofwaterandgasassistedinjectionmolding.Withincreasingdemandsformaterialswithimprovedperformance,whichmaybecharacterizedbythecriteriaoflowerweight,higherstrength,andafasterandcheaperproductioncycletime,theengineeringofplasticsisaprocessthatcannotbeignored.Theseplasticsincludethermoplasticandthermosetpolymers.Ingeneral,thermoplasticpolymershaveanadvantageoverthermosetpolymersinpopularmaterialsinstructuralapplications.Poly-butylene-terephthalate(PBT)isoneofthemostfrequentlyusedengineeringthermoplasticmaterials,whichisformedbypolymerizing1.4butyleneglycolandDMTtogether.Fiber-reinforcedcompositematerialshavebeenadaptedtoimprovethemechanicalpropertiesofneatplasticmaterials.Today,shortglassfiberreinforcedPBTiswidelyusedinelectronic,communicationandautomobileapplications.Therefore,theinvestigationoftheprocessingoffiber-reinforcedPBTisbecomingincreasinglyimportant[7–10].Thisreportwasmadetoexperimentallystudythewaterassistedinjectionmoldingprocessofpoly-butylene-terephthalate(PBT)materials.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedavirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,whichincludedmelttemperature,moldtemperature,meltfillingspeed,short-shotsize,waterpressure,watertemperature,waterholdandwaterinjectiondelaytime.Mechanicalpropertytestswerealsoperformedonthesemoldedparts,andXRDwasusedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.
Table1
Advantagesanddisadvantagesofwater-assistedinjectionmolding
Advantages
Disadvantages
1.Shortcycletime
1.Corrosionofthesteelmoldduetowater
2.Lowassistingmediumcost(waterismuchcheaperandcanbeeasilyrecycled)
2.Largerorificesfortheinjectionpinrequired(easiertogetstuckbythepolymermelt)
3.Nointernalfoamingphenomenoninmoldedparts
3.Somematerialsaremoredifficulttomold(especiallyamorphousthermoplastics)
4.Removalofwateraftermoldingisrequired
2.Experimentalprocedure
2.1.Materials
ThematerialsusedincludedavirginPBT(Grade1111FB,Nan-YaPlastic,Taiwan)anda15%glassfiberfilledPBTcomposite(Grade1210G3,Nan-YaPlastic,Taiwan).Table3liststhecharacteristicsofthecompositematerials.
2.2.Waterinjectionunit
Alabscalewaterinjectionunit,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit,wasusedforallexperiments[3].Anorifice-typewaterinjectionpinwithtwoorifices(0.3mmindiameter)onthesideswasusedtomoldtheparts.Duringtheexperiments,thecontrolcircuitofthewaterinjectionunitreceivedasignalfromthemoldingmachineandcontrolledthetimeandpressureoftheinjectedwater.Beforeinjectionintothemoldcavity,thewaterwasstoredinatankwithatemperatureregulatorfor30mintosustainanisothermalwatertemperature.
2.3.Moldingmachineandmolds
Water-assistedinjectionmoldingexperimentswereconductedonan80-tonconventionalinjection-moldingmachinewithahighestinjectionrateof109cm3/s.Aplatecavitywithatrapezoidalwaterchannelacrossthecenterwasusedinthisstudy.Fig.2showsthedimensionsof
thecavity.Thetemperatureofthemoldwasregulatedbyawater-circulatingmoldtemperaturecontrolunit.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinwaterchannelsofmoldedparts:
melttemperature,moldtemperature,melt
fillpressure,watertemperatureandpressure,waterinjectiondelaytimeandholdtime,andshortshotsizeofthepolymermelt.Table4liststheseprocessingvariablesaswellasthevaluesusedintheexperiments.
2.4.Gasinjectionunit
Inordertomakeacomparisonofwaterandgas-assistedinjectionmoldedparts,acommerciallyavailablegasinjectionunit(GasInjectionPPC-1000)wasusedforthegasassistedinjectionmoldingexperiments.DetailsofthegasinjectionunitsetupcanbefoundintheRefs.[11–15].Theprocessingconditionsusedforgas-assistedinjectionmoldingwerethesameasthatofwater-assistedinjectionmolding(termsinboldinTable4),withtheexceptionofgastemperaturewhichwassetat25_C.
2.5.XRD
Inordertoanalyzethecrystalstructurewithinthewater-assistedinjection-moldedparts,wide-angleX-raydiffraction(XRD)with2DdetectoranalysesintransmissionmodewereperformedwithCuKaradiationat40kVand40mA.Morespecifically,themeasurementswereperformedonthemold-sideandwater-sidelayersofthewater-assistedinjection-moldedparts,withthe2hanglerangingfrom7_to40_.Thesamplesrequiredfortheseanalysesweretakenfromthecenterportionofthesemoldedparts.ToobtainthedesiredthicknessfortheXRDsamples,theexcesswasremovedbypolishingthe
Table3
Characteristicsoftheglass–fiberreinforcedPBTcomposite
Property
ASTMPBT15%G.F.PBT
Yieldstrength(kg/cm2)
D-6386001000
Bendingstress(kg/cm2)
D-5709001500
Hardness(R-scale)
D-785119120
Heatdistortiontemperature(_C)
(18.6kg/cm2)