塑胶射出成型问题和模具的关系

OLETechnologyCorporation徐昌煜CharlesHsu歐磊科技股份有限公司OLETechnologyCorporation塑膠射出成型問題和模具的關係MoldRelatedPlasticInjectionMoldingProblemsOLETechnologyCorporationConcentricrecordgroovesOLETechnologyCorporation流痕FlowLineorFlowMark流痕(FlowLineorFlowMark)的定義:成型品表面的線狀痕跡，此一痕跡顯示了熔膠流動的方向。OLETechnologyCorporationRecordGroovesFlowfrontcoolsdownnearthewallCooleddownouterlayerimpedesdirectfrontalflowtothewallFlowfronttouchesmoldwallagainOLETechnologyCorporation模具1.模溫太低模溫太低會使得料溫下降太快，射壓和保壓不足以將冷凝的表皮緊壓在模面上，留下熔膠在垂直流動方向的縮痕，狀如年輪。提高模溫，保持較高料溫，射壓和保壓將冷凝層緊壓在模面上，直到製品定型，流痕無由產生。模溫可從材料廠商的建議值開始設定。每次調整的增量可為6°C，射膠10次，成型情況穩定後，根據結果，決定是否進一步調整。流痕FlowLineorFlowMarkOLETechnologyCorporation模具2.澆道(Sprue)、流道(Runner)或/和澆口(Gate)太小澆道、流道或/和澆口太小，流阻提高，如果射壓不足，熔膠波前的推進會愈來愈慢，塑料會愈來愈冷，射壓和保壓不足以將冷凝的表皮緊壓在模面上，留下熔膠在垂直流動方向的縮痕，狀如年輪。以CAE在電腦上對不同的熔膠傳送系統(包括澆道、流道和澆口)的充填進行模擬分析，找出理想的澆道、流道和澆口的尺寸(包括長度和斷面有關尺寸如直徑等)，是可行之道。流痕FlowLineorFlowMarkOLETechnologyCorporation矩形邊緣澆口設計RectangularEdgeGateDesignL=0.5~0.75mmW=澆口寬度(mm)gatewidthinmmA=型腔表面積(mm)surfaceareaofcavityinmmn=材料常數materialconstant0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVC22h=nth=澆口厚度(gatethick.inmm)t=零件壁厚(wallthick.inmm)WtLh30AnWOLETechnologyCorporation充填時間長將產生流痕FlowLinesduetoLongFillTime凸片澆口厚度為1.5mm側壁厚度為3mmPCOLETechnologyCorporation流道尺寸設計(1)RunnerSizing(1)D:流道直徑(mm)runnerdiameterinmmW:下游塑膠重量(g)downstreamplasticweightL:流道長度(mm)runnerlengthinmmDWL3.74OLETechnologyCorporation流道尺寸設計(2)RunnerSizing(2)OLETechnologyCorporation流道尺寸設計(3)RunnerSizing(3)mmDgcmcmcmgWmmLLWD3~38.214.144102.0/9.0307.31223114111OLETechnologyCorporation流道尺寸設計(4)RunnerSizing(4)mmDgggcmcmcmgWWmmLLWD5~33.466.28219.014.14243.03/9.0807.322231224222OLETechnologyCorporationOLETechnologyCorporationHHSSHSL508.010cos2210cosHHSWSW088.0508.010sin10sin10sinH/2(L)OLETechnologyCorporation5432654321AAAAandAAAAAAA2221349.0294360160HHRA22022.022088.022HHHHWA222088.0022.044HHA26508.02508.0222HHHHSA22621945.0508.0088.0349.04HHAAAAOLETechnologyCorporationSWArcP41HRArc396.123601601HHHSW596.0508.0088.0mmDHmmDH533.4338.22211HHHP780.3596.04396.1HHHPADH780.3945.0442OLETechnologyCorporation比較圓形流道截面積(AR)與改良型梯形流道截面積(AT)。假設圓形流道的直徑與改良型梯形流道的高度相等。Comparingthecross-sectionalareaoffull-roundrunner(AR)andtheoneofmodifiedtrapezoidal(AT),whenthediameteroftheroundrunnerandtheheightofthetrapezoidalrunnerarethesame.%38.20785.0785.0945.0945.0945.0785.042222RRTTRAAADHADDAOLETechnologyCorporation換言之，改良型梯形流道所使用的材料比圓形流道的材料多了20.38%。Inotherwords，modifiedtrapezoidalrunneruses20.38%morematerialthanfull-roundrunnerdoes.OLETechnologyCorporation3.排氣(Venting)不足排氣不良，會使得熔膠充填受阻，熔膠波前無法將冷凝的表皮緊壓在模面上，留下熔膠在垂直流動方向的縮痕，狀如年輪。在每一段流道末端考慮排氣，可以避免氣體進入型腔。型腔排氣更不能輕忽。最好採用全周長排氣。CAE模擬熔膠充填，可以幫我們很快的找到所有可能的最後充填處(LastFilledArea)，也就是須要加排氣孔的地方。按圖索驥，萬無一失。模具流痕FlowLineorFlowMarkOLETechnologyCorporation為何排氣仍然還是一個問題？Whyventingisstillaproblem?因為降低射速，讓積風有較多的時間逃氣，是一件太容易的事。但是…Becauseitistooeasytoslowdowntheinjectionspeedandgivethetrappedairmoretimetoescape.But...排氣VentOLETechnologyCorporation射速一降，熔膠溫度很快降低，射壓必須提高，殘餘應力隨之提高，翹曲的可能性增加。如果想藉提高料溫，以降低射壓，料溫必須升得很高，這樣又會引起塑料裂解。Wheninjectionspeedislower,melttemperaturegoesdownveryfast,injectionpressurehastobeincreased,residualstressisincreasedandthepossibilitygettingwarppagebecomeshigher.Ifonewouldliketoincreasebarreltemperaturetoreducetherequiredinjectionpressure,thebarreltemperaturehastobeincreasedtoaquitehighlevelandpolymerdegradationwouldbeinduced.排氣VentOLETechnologyCorporation有了適當的排氣，射速可以提高，充填和保壓可達良好狀態，不須過度增加料管和噴嘴的溫度。Withproperventing,theinjectionspeedcouldbeincreasedtoachievegoodfillandpackconditions,withouthavingtoraisethebarrelandnozzleheats,improperly.排氣VentOLETechnologyCorporation深度(depth):1.0.075mm易流塑料(easy-flowmat.)2.0.125mm難流塑料(stiffer-flowmat.)3.深度深到流道末端見毛邊為準(deepenoughtofeelflashatrunnerend)寬度(width):和流道同寬(aswideasrunnerdia.)排氣唇部(ventlip):1.5mmA1拋光(finish)排氣通道通大氣(ventchanneltoatmosphere):1mm深(deep)流道排氣RunnerVentsOLETechnologyCorporation流道排氣RunnerVentsOLETechnologyCorporation深度(depth):參照廠商建議(refertomanufacturer’srecommendation)寬度(width):全圓周長(wholeperimeter)or5mm/25mm長度(length):1.5mmor1mmA1拋光(finish)排氣通道通大氣(ventchanneltoatmosphere):1mm深(deep)分模面排氣PartingLineVentsOLETechnologyCorporation分模面排氣PartingLineVentsOLETechnologyCorporationMaterial:PC-GFOLETechnologyCorporation深度(depth):參照廠商建議(refertomanufacturer’srecommendation)寬度(width):全圓周長(wholeperimeter)長度(length):1.5mm排氣溝(ventgroove):1mm深(deep)頂出銷或心型銷排氣EjectorandCorePinVentsOLETechnologyCorporationVENTINGGUIDELINESFORFULLYOPTIMIZEDMOLDSPOLYMERDEPTHOFVENT(mm)EASYFLOWSTIFFFLOWGLASSFILLEDABS,SAN,HIPS0.05080.0762Acetal0.01270.0381Acrylic0.05080.0762Cellulose/Acetate/Butyrate0.02540.0381Nylon6/60.0127—Nylon6/6–13%Glass0.01270.0381Polyallomers0.01270.0254Polycarbonate0.03810.0762Polyethylene0.02540.0508Polypropylene0.02540.0508PolyphenyleneOxide0.02540.0762PolyphenyleneSulfide0.0127—Polysulfone0.0254—CrystalPolystyrene0.02540.0508Polyvinylchloride(Rigid)0.02540.0762Polyvinylchloride(Plasticized)0.