




已閱讀5頁,還剩5頁未讀, 繼續免費閱讀
版權說明:本文檔由用戶提供并上傳,收益歸屬內容提供方,若內容存在侵權,請進行舉報或認領
文檔簡介
form7NovemberFig.1.Water-assistedinjectionmoldingcanproducepartsincorporatingboththickandthinsectionswithlessshrink-involved.Watermayalsocorrodethesteelmold,andsomematerialsincludingthermoplasticcompositesarediculttomoldsuccessfully.Theremovalofwateraftermoldingisalsoachallengeforthisnoveltechnology.Table1liststheadvantagesandlimitationsofwater-assistedinjectionmoldingtechnology.*Correspondingauthor.Address:259,Wen-Hwa1stRoad,Kwei-San,Tao-Yuan333,Taiwan.E-mailaddress:.tw(S.-J.Liu).CompositesScienceandTechnologyCOMPOSITES1.IntroductionWater-assistedinjectionmoldingtechnology1hasproveditselfabreakthroughinthemanufactureofplasticpartsduetoitslightweight,fastercycletime,andrelativelylowerresincostperpart.Inthewater-assistedinjectionmoldingprocess,themoldcavityispartiallyfilledwiththepolymermeltfollowedbytheinjectionofwaterintothecoreofthepolymermelt.Aschematicdiagramofthewater-assistedinjectionmoldingprocessisillustratedinageandwarpageandwithabettersurfacefinish,butwithashortercycletime.Thewater-assistedinjectionmoldingprocesscanalsoenablegreaterfreedomofdesign,materialsavings,weightreduction,andcostsavingsintermsoftool-ingandpresscapacityrequirements24.Typicalapplica-tionsincluderodsandtubes,andlargesheet-likestructuralpartswithabuilt-inwaterchannelnetwork.Ontheotherhand,despitetheadvantagesassociatedwiththeprocess,themoldingwindowandprocesscontrolaremorecriticalanddicultsinceadditionalprocessingparametersareAbstractThepurposeofthisreportwastoexperimentallystudythewater-assistedinjectionmoldingprocessofpoly-butylene-terephthalate(PBT)composites.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsys-tem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedvirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,andmechanicalpropertytestswereperformedontheseparts.X-raydiraction(XRD)wasalsousedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.Itwasfoundthatthemeltfillpressure,melttemperature,andshortshotsizewerethedominantparametersaectingwaterpenetrationbehavior.Materialatthemold-sideexhibitedahigherdegreeofcrystallinitythanthatatthewater-side.Partsmoldedbygasalsoshowedahigherdegreeofcrystallinitythanthosemoldedbywater.Furthermore,theglassfibersnearthesurfaceofmoldedpartswerefoundtobeori-entedmostlyintheflowdirection,butorientedsubstantiallymoreperpendiculartotheflowdirectionwithincreasingdistancefromtheskinsurface.C2112006ElsevierLtd.Allrightsreserved.Keywords:Waterassistedinjectionmolding;Glassfiberreinforcedpoly-butylene-terephthalate(PBT)composites;Processingparameters;B.Mechanicalproperties;Crystallinity;A.Polymermatrixcomposites;ProcessingAnexperimentalstudyofthewater-assistedglassfiberfilledpoly-butylene-terephthalateShih-JungLiu*,Ming-JenPolymerRheologyandProcessingLab,DepartmentofMechanicalReceived12September2005;receivedinrevisedAvailableonline0266-3538/$-seefrontmatterC2112006ElsevierLtd.Allrightsreserved.doi:10.1016/pscitech.2006.09.016injectionmoldingof(PBT)compositesLin,Yi-ChuanWuEngineering,ChangGungUniversity,Tao-Yuan333,Taiwan29June2006;accepted11S/locate/compscitech67(2007)14151424SCIENCEANDTECHNOLOGYTable2Acomparisonofwaterandgas-assistedinjectionmoldingWaterGas1.CycletimeShortLong2.MediumcostLowHigh3.InternalfoamingNoYes4.ResidualwallthicknessSmallLarge5.OutsidesurfaceroughnessLowHigh6.OutsidesurfaceglossHighLow1416S.-J.Liuetal./CompositesScienceandTechnology67(2007)14151424Waterassistedinjectionmoldinghasadvantagesoveritsbetterknowncompetitorprocess,gasassistedinjectionmolding5,becauseitincorporatesashortercycletimetosuccessfullymoldapartduetothehighercoolingcapac-Fig.1.Schematicdiagramofwater-assistedinjectionmoldingprocess.ityofwaterduringthemoldingprocess.Theincompress-ibility,lowcost,andeaseofrecyclingthewatermakesitanidealmediumfortheprocess.Sincewaterdoesnotdis-solveanddiuseintothepolymermeltsduringthemoldingprocess,theinternalfoamingphenomenon6thatusuallyoccursingas-assistedinjectionmoldedpartscanbeelimi-nated.Inaddition,waterassistedinjectionmoldingpro-videsabettercapabilityofmoldinglargerpartswithasmallresidualwallthickness.Table2listsacomparisonofwaterandgasassistedinjectionmolding.Withincreasingdemandsformaterialswithimprovedperformance,whichmaybecharacterizedbythecriteriaoflowerweight,higherstrength,andafasterandcheaperproductioncycletime,theengineeringofplasticsisapro-cessthatcannotbeignored.Theseplasticsincludethermo-plasticandthermosetpolymers.Ingeneral,thermoplasticpolymershaveanadvantageoverthermosetpolymersinTable1Advantagesanddisadvantagesofwater-assistedinjectionmoldingAdvantagesDisadvanta1.Shortcycletime2.Lowassistingmediumcost(waterismuchcheaperandcanbeeasilyrecycled)3.Nointernalfoamingphenomenoninmoldedparts.termsofhigherimpactstrength,fractureresistanceandstrains-to-failure.Thismakesthermoplasticpolymersverypopularmaterialsinstructuralapplications.Poly-butylene-terephthalate(PBT)isoneofthemostfrequentlyusedengineeringthermoplasticmaterials,whichisformedbypolymerizing1.4butyleneglycolandDMTtogether.Fiber-reinforcedcompositematerialshavebeenadaptedtoimprovethemechanicalpropertiesofneatplas-ticmaterials.Today,shortglassfiberreinforcedPBTiswidelyusedinelectronic,communicationandautomobileapplications.Therefore,theinvestigationoftheprocessingoffiber-reinforcedPBTisbecomingincreasinglyimportant710.Thisreportwasmadetoexperimentallystudythewater-assistedinjectionmoldingprocessofpoly-butylene-tere-phthalate(PBT)materials.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedavirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavity7.FingeringGreaterLess8.AsymmetricalpenetrationMorestableUnstable9.MaterialcrystallinityLowHigh10.ParttransparencyHighLow11.Internalsurface(semi-crystallinematerials)SmoothLesssmooth12.Internalsurface(amorphousmaterials)RoughSmoothwitharibacrosscenterwasused.Variousprocessingvari-ableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,whichincludedmelttemperature,moldtemperature,meltfillingspeed,short-shotsize,waterpressure,watertemperature,waterholdandwaterinjectiondelaytime.Mechanicalpropertytestswerealsoperformedonthesemoldedparts,andXRDwasusedtoidentifythematerialandstructuralgesCorrosionofthesteelmoldduetowaterLargerorificesfortheinjectionpinrequired(easiertogetstuckbythepolymermelt)Somematerialsaremorediculttomold(especiallyamorphousthermoplastics)Removalofwateraftermoldingisrequiredparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.2.Experimentalprocedure2.1.MaterialsThematerialsusedincludedavirginPBT(Grade1111FB,Nan-YaPlastic,Taiwan)anda15%glassfiberfilledPBTcomposite(Grade1210G3,Nan-YaPlastic,Tai-wan).Table3liststhecharacteristicsofthecompositematerials.polymermelt.Table4liststheseprocessingvariablesaswellasthevaluesusedintheexperiments.2.4.GasinjectionunitInordertomakeacomparisonofwaterandgas-assistedinjectionmoldedparts,acommerciallyavailablegasinjec-tionunit(GasInjectionPPC-1000)wasusedforthegas-assistedinjectionmoldingexperiments.DetailsofthegasinjectionunitsetupcanbefoundintheRefs.1115.Theprocessingconditionsusedforgas-assistedinjectionmoldingwerethesameasthatofwater-assistedinjectionmolding(termsinboldinTable4),withtheexceptionofgastemperaturewhichwassetat25C176C.2.5.XRDInordertoanalyzethecrystalstructurewithinthewater-assistedinjection-moldedparts,wide-angleX-raydiraction(XRD)with2Ddetectoranalysesintransmis-sionmodewereperformedwithCuKaradiationat40kVand40mA.Morespecifically,themeasurementswereperformedonthemold-sideandwater-sidelayersofthewater-assistedinjection-moldedparts,withthe2hanglerangingfrom7C176to40C176.ThesamplesrequiredfortheseanalysesweretakenfromthecenterportionoftheseFig.2.Layoutanddimensionsofmoldcavity(unit:mm).S.-J.Liuetal./CompositesScienceand2.2.WaterinjectionunitAlabscalewaterinjectionunit,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit,wasusedforallexperiments3.Anori-fice-typewaterinjectionpinwithtwoorifices(0.3mmindiameter)onthesideswasusedtomoldtheparts.Duringtheexperiments,thecontrolcircuitofthewaterinjectionunitreceivedasignalfromthemoldingmachineandcon-trolledthetimeandpressureoftheinjectedwater.Beforeinjectionintothemoldcavity,thewaterwasstoredinatankwithatemperatureregulatorfor30mintosustainanisothermalwatertemperature.2.3.MoldingmachineandmoldsWater-assistedinjectionmoldingexperimentswerecon-ductedonan80-tonconventionalinjection-moldingmachinewithahighestinjectionrateof109cm3/s.Aplatecavitywithatrapezoidalwaterchannelacrossthecenterwasusedinthisstudy.Fig.2showsthedimensionsofthecavity.Thetemperatureofthemoldwasregulatedbyawater-circulatingmoldtemperaturecontrolunit.Variousprocessingvariableswereexaminedintermsoftheirinflu-enceonthelengthofwaterpenetrationinwaterchannelsofmoldedparts:melttemperature,moldtemperature,meltfillpressure,watertemperatureandpressure,waterinjec-tiondelaytimeandholdtime,andshortshotsizeoftheTable3CharacteristicsoftheglassfiberreinforcedPBTcompositePropertyASTMPBT15%G.F.PBTYieldstrength(kg/cm2)D-6386001000Bendingstress(kg/cm2)D-5709001500Hardness(R-scale)D-785119120Heatdistortiontemperature(C176C)(18.6kg/cm2)D-64860200Meltflowindex(MFI)D-12384025Impactstrength(Kg-cm/cm)D-25655Meltingtemperature(C176C)DSC224224Technology67(2007)141514241417moldedparts.ToobtainthedesiredthicknessfortheXRDsamples,theexcesswasremovedbypolishingthesamplesonarotatingwheelonarotatingwheel,firstwithwetsiliconcarbidepapers,thenwith300-gradesiliconcar-bidepaper,followedby600-and1200-gradepaperforabettersurfacesmoothness.2.6.MechanicalpropertiesTensilestrengthandbendingstrengthweremeasuredonatensiletester.Tensiletestswereperformedonspecimensobtainedfromthewater-assistedinjectionmoldedparts(seeFig.3)toevaluatetheeectofwatertemperatureon20mm10mm1mm.BendingtestswereperformedinamicrotensiletesteraccordingtotheASTMD256test.A200Nloadcellwasusedandthecrossheadspeedwas50mm/min.2.7.MicroscopicobservationThefiberorientationinmoldedspecimenswasobservedunderascanningelectronmicroscope(JeolModel5410).Specimensforobservationwerecutfrompartsmoldedbywater-assistedinjectionmoldingacrossthethicknessTable4TheprocessingvariablesaswellasthevaluesusedintheexperimentsABCDEFMeltpressure(Mpa)Melttemperature
溫馨提示
- 1. 本站所有資源如無特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請下載最新的WinRAR軟件解壓。
- 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請聯系上傳者。文件的所有權益歸上傳用戶所有。
- 3. 本站RAR壓縮包中若帶圖紙,網頁內容里面會有圖紙預覽,若沒有圖紙預覽就沒有圖紙。
- 4. 未經權益所有人同意不得將文件中的內容挪作商業或盈利用途。
- 5. 人人文庫網僅提供信息存儲空間,僅對用戶上傳內容的表現方式做保護處理,對用戶上傳分享的文檔內容本身不做任何修改或編輯,并不能對任何下載內容負責。
- 6. 下載文件中如有侵權或不適當內容,請與我們聯系,我們立即糾正。
- 7. 本站不保證下載資源的準確性、安全性和完整性, 同時也不承擔用戶因使用這些下載資源對自己和他人造成任何形式的傷害或損失。
最新文檔
- 社區教育中心委托管理及教學資源整合與開發協議
- 國際會議同傳翻譯培訓室租賃及翻譯人才引進協議
- 美團酒店商家數據監測與酒店行業合作拓展合同
- 股權激勵計劃中員工優先購買權合作協議
- 外資企業拉美市場運營專員職務聘用及保密合同
- 貨運合同運輸服務質量保證補充協議
- 生物醫藥企業股東除名與股權重組及激勵方案協議
- 校招英文測試題庫及答案
- 職業院校外聘教師教學成果評價與獎勵合同
- 影視作品群眾演員安全與責任合同
- 巴西詳細教案
- 基于PLC控制的物料分揀系統設計
- 上期開特下期出特公式
- 案件進度管理規定表--執行
- 人教部編版七年級歷史下冊教材插圖匯總
- 建筑工程竣工驗收報告山西
- 啟閉機房腳手架工程施工專項方案
- 變更監事模板
- 前部分拼音四聲調
- 標準工程量清單細目編號公路工程
- 股東大會律師見證的法律意見書范本
評論
0/150
提交評論