塑料注射工艺基础

1、塑料注射成型工艺基础塑料注射成型工艺基础内容提要 注射工艺过程 注射压力 填充模式 浇注系统与流道平衡 冷却系统 应力、收缩与翘曲 常见的注塑缺陷 CAE软件应用指南 Co-injection molding Fusible core injection moldingGas-assisted injection moldingInjection-compression moldingLamellar (microlayer) injection moldingLive-feed injection moldingLow-pressure injection moldingPush-pull

2、injection moldingStructural foam injection moldingProcess cycle Importance of process conditions Resin data table Generic NameMelt Temperature (C/F)Mold Temperature (C/F) Min.Rec.Max.Min.Rec.Max.ABS 200/392 230/446 280/536 25/77 50/122 80/176 PA 6 230/446 255/491 300/572 70/158 85/185 110/230 PC 260

3、/500 305/581 340/644 70/158 95/203 120/248 PET 265/509 270/518 290/554 80/176 100/212 120/248 PMMA 240/464 250/482 280/536 35/90 60/140 80/176 POM 180/356 225/437 235/455 50/122 70/158 105/221 PP 200/392 230/446 280/536 20/68 50/122 80/176 PS 180/356 230/446 280/536 20/68 50/122 70/158 PVC 160/320 1

4、90/374 220/428 20/68 40/104 70/158 SAN 200/392 230/446 270/518 40/104 60/140 80/176 Temperature-time curve at various locations in the mold Screw positions at various stagesCycle time and its components Required mold openingDetermination of the gate/part freezing time Pressure decreases along the de

5、livery system and the cavityFactors influencing injection pressure requirements (I)VariableHigherinjectionp r e s s u r erequiredLowerinjectionp r e s s u r erequiredPARTDESIGNPartthicknessPartsurfaceareaFactors influencing injection pressure requirements (II)VariableHigherinjectionp r e s s u r ere

6、quiredLowerinjectionp r e s s u r erequiredGATEDESIGNGatesizeFlowlengthFactors influencing injection pressure requirements (III)VariableHigherinjectionp r e s s u r erequiredLowerinjectionp r e s s u r erequiredPROCESSINGCONDITIONSMelttemperaturePartsurfaceareaRamspeedFactors influencing injection p

7、ressure requirements (IV)VariableHigherinjectionp r e s s u r erequiredLowerinjectionp r e s s u r erequiredMATERIALSELECTIONMeltflowindexInjection pressure as a function Melt front advancementsMelt-front velocity and melt-front areaFiber orientationsVariation of MFA Basic runner system layouts Comm

8、only used runner cross sections Equivalent hydraulic diametersRunner diameter chartEffect of runner lengthHot runner system typesFilling patterns resulting from various injection ratesCold slug A family-mold part with artificially balanced runners Gate size terminology FIGURE 1. Gate size terminology Gate types （I）Direct (sprue) gate Tab gateEdge (standard) gate Overlap gateFan gateDisk (diaphragm) gateGate types （II） Ring gateSpoke (spider) gateFilm (flash) gateMold cooling accounts for more than two-thirds of the total