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塑膠產品設計PlasticPartDesign就傳統射出成形而言，實用的最小壁厚在0.75到1.00mm之間。如果要採用更薄的壁厚，卻又缺乏實際的經驗，可以借助CAE作科學的決定。Forconventionalinjectionmolding,apracticalminimumwallthicknessisintherangeof0.75to1.00mm.Whenthinnerwallsarerequiredbutactualexperienceisabsent,theminimumpossiblethicknesscanbescientificallydeterminedbyCAE.壁厚WallThickness壁厚不均是注塑成形中最大的麻煩製造者。這對薄壁零件尤然。這些麻煩包括了遲滯現象、短射、凹陷、發赤、噴流、翹曲及長冷卻時間等；目前都可用CAE以直接或間接的方式預測。Non-uniformwallthicknessisthebiggesttroublemakerinplasticinjectionmolding.Thisisespeciallytruetothin-wallpart.Thetroubles,includinghesitation,shortshot,sinkmark,blush,jetting,warpageandlongcoolingtimeetc.,canbepredicted,directlyorindirectly,byusingCAE.壁厚不均Non-uniformWallThickness設計高收縮率材料成型品時，設計者應將壁厚變化限制在10%。就低收縮率材料而言，許容壁厚變化可到25%。Whiledesigninginjectionmoldedpartsinhighmoldshrinkagefactormaterials,thedesignershouldtrytolimitwallthicknessvariationto10%.Theallowablewallthicknessvariationforthelowmoldshrinkagefactormaterialscanbeupto25%.壁厚不均Non-uniformWallThickness壁厚設計WallThicknessDesign差[Poor]較好[Better]最好[Best]掏空設計(1)CoringOutDesign(1)改進設計[Improved]原設計[Original]差[Poor]改進[Improved]掏空設計(2)CoringOutDesign(2)外側凸轂OutsideBossA'A'A(DIA)BB=AB=2A(max.)SectionA'-A'熔接線70100熔接線空洞或/和凹陷的形成Voidor/andSinkMarkForming空洞(Void)凹陷(SinkMark)肋厚和內圓角半徑的影響TheEffectofRibThickness&FilletRadius突出件和公稱厚壁相交處的內圓角半徑太大，會致使凹陷、空洞、殘餘應力和長的冷卻時間。該內圓角半徑太小，會致使應力集中。一個好的折中方案是採用公稱壁厚的25%，作為內圓角半徑。Alargefilletradiuscausessinkmark,void,residualstressandlongcoolingtime.Asmallfilletradiuscausesstressconcentration.Agoodcompromiseistousearadius,whichis25%ofthenominalwall(NW),atthejunctionoftheNWandaprojection.內圓角半徑FilletRadius肋的底部厚度BottomThicknessofRibW0.5W2.5WW1.2WD1.5WD(A)(B)肋的設計(一)RibDesign(1)t=wallthichnessB=0.5tC=3tAAD=2BE=0.13mm(radius)F=1.5-2deg假如需要更大的強度,可增加肋的數目Ifmorestrengthisrequired,addadditionalribs.FBDECt肋的設計(二)RibDesign(2)角板設計(三)GussetDesign(3)與側壁相連之凸轂(熱塑性塑膠)BossatWall(Thermoplastics)A=凸轂附著處壁厚wallthicknessB=凸轂外環直徑dia.ofbossoverradiiC=0.5AD=2BE=1~2degF=0.13mm(radius)G=DH=0.8AI=A/4J=2BK=0.3~1JL=0.5ALHA'A'KEIGJDAFCBSectionA'-A'遠離側壁之凸轂(熱塑性塑膠)BossAwayFromWall(Thermoplastics)A=凸轂附著處壁厚wallthicknessB=凸轂外環直徑(含底部修整圓弧半徑)dia.ofbossoverradiiC=0.5AD=2BE=1-2degF=0.13mm(radius)G=0.95DH=0.3Gmin.toGmax.I=0.5AHEFDFGCBAIWallThickness,RibConventional0.080to0.125in(2.0to3.2mm)owallwallribmmrthtt21375.046.0Thinwall:0.050to0.080in0.050in(1.2to2.0mm)(1.2mm)oowallwallwallwallribtmmrthttt121*6.0375.046.0owallwallwallribtrthtt1*6.0*4WallThickness,BossesConventional0.080to0.125in(2.0to3.2mm)IDODmmrthttowallwallboss221375.046.0Thinwall:0.050to0.080in0.050in(1.2to2.0mm)(1.2mm)IDODtmmrthtttoowallwallwallwallboss2121*6.0375.046.0IDODtrthttowallwallwallboss21*6.0*4WallThickness,GussetsConventional0.080to0.125in(2.0to3.2mm)owallwallgussetmmrthtt21375.046.0Thinwall:0.050to0.080in0.050in(1.2to2.0mm)(1.2mm)oowallwallwallwallgussettmmrthttt121*6.0375.046.0owallwallwallgussettrthtt1*6.0*4突出件在和公稱厚壁相交處的建議厚度：以高縮水率的結晶性塑膠而言，可採用公稱壁厚的50%。以低縮水率的非結晶性塑膠而言，可採用公稱壁厚的75%。Therecommendedthicknessatthejunctionofaprojectionandthenominalwall(NW)is50%oftheNWthicknessforhigh-mold-shrinkage,crystallinematerials.Thelower-mold-shrinkage-factor,amorphousplasticscanhavethicknessesofupto75%ofthepart’sNWthickness.突出件壁厚ThicknessoftheProjection有些情形，在美觀的考慮下，是不容許些微凹陷的。設計者應當考慮將建議厚度減少10%。Inthosecaseswhereaestheticconsiderationsprecludeevenaslightsinkmark,adesignershouldconsiderreducingtherecommendedribthicknessbyanadditional10percent.突出件壁厚ThicknessoftheProjection從成型容易的觀點來看，突出件的高度以產品公稱壁厚的2.5到3倍為宜。Fromaneaseofmoldingperspective,theheightofprojectionsshouldbelimitedto2.5to3timesthepartnominalwallthickness.突出件高度HeightoftheProjection強固的、脆的、剝蝕性的、黏的塑件要有大的脫模角和光滑的拋光。軟的、延展性的、和光滑的塑件則可有小的脫模角。Largedraftanglesandasmoothpolisharerequiredforpartsmoldedinstrong,brittle,abrasive,andstickymaterials.Smallerdraftanglescanbeusedonsoft,ductile,andslipperymaterials.突出件脫模角DraftAngleoftheProjection以成本和可製造性的觀點，理想的脫模角是消費者可以接受的前題下，最大的角度。就多數情況而言，每邊1°應已足夠，但2°或5°可以更好。模穴應順著開模方向打光。Theidealdraftangle,fromacostandmanufacturabilityperspective,isthelargestanglethatwillnotdistractfromtheconsumer’sacceptanceoftheproduct.Inmostcases,1°persidewillbeadequate,but2°or5°persidewouldbebetter.Thecavitiesthatformprojectionsshouldbedraw-polished.突出件脫模角DraftAngleoftheProjection距離應大於產品公稱壁厚的2倍。使得模具鋼材具備足夠的強度以抵抗彎曲，並且提供足夠的吸熱器，以免產生凹陷和成型應力。Thisdistanceshouldbeatleast2timesthepart’snominalwallthickness,sothemoldsteelprovideenoughstrengthtoresistbendingandenoughheatsinktoavoidsinkmarkandmoldedinstress.突出件和側壁/突出件的距離TheDistancebetweenProjectionandSideWall/ProjectionAAAAA-AA-ALongRibAirTrapEIMr1Where1/r:樑的曲率curvatureofthebeamM:彎曲力矩bendingmomentE:彈性模數modulusofelasticityI:斷面積對中立軸的慣性矩momentofinertiaofthecross-sectionalareawithrespecttotheneutralaxisEI:撓曲剛性flexuralrigidity撓曲剛性FlexuralRigidityIWLyEIWLCmax3max3Wmax樑BeamLWhere:最大偏移maximumdeflectionW:負荷loadL:樑長lengthofbeamE:彈性模數modulusofelasticityI:斷面積對中立軸的慣性矩momentofinertiaofthecross-sectionalareawithrespecttotheneutralaxisEI:撓曲剛性flexuralrigidity:最大應力maximumstress:中立軸到到其斷面離其