塑料件注塑基本知识.ppt

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2025,塑料件注塑基本知识,热固性塑料的填料,粉状填料,滑石粉,云母粉,石英粉,流动好,比容小,塑料性脆,成型压力小.,木粉,流动好,比容小,易吸湿.,热固性塑料的填料,纤维填料,棉纤维,石纤维,碎布纤维.,流动性差,比容大,易吸湿,成型压力大,强度好.,填充性不良,易熔接不良.,玻璃纤维,流动性差,方向明显.,比容大,装模不便,模具磨损大.,加压时机:过早,填料与树脂分离,溢料多.过晚易发生填充不足.,热塑性塑料,成形收缩率,塑料粒子,分子量大小,结晶/非结晶.,塑件结构,嵌件布局/数量,料流方向,料流方向大，垂直小,玻纤增强：料流方向小，垂直大,浇口形式,尺寸,分布,成型条件,热塑性塑料,流动性好,分子量大小:分子量小,分子量分布寛.,分子结构规整性差,熔融指数高,表现粘度小,流动比大.,热塑性塑料,结晶性,结晶型,壁薄,冷却快,结晶低,收缩小,透明度高,各向异性,内应力大.,易变形,翘曲,非结晶型,热塑性塑料,热敏性及水敏性,热敏性:料温高,易变色,易降解,对模具的腐蚀大.,水敏性:在有水的情况下,在高温,高压下会降解.,热塑性塑料,吸湿性,吸湿,粘附水份,不易吸湿,粘附水份,水解使树脂起泡,流动性下降,外观及机电性能不良.,塑件设计,脱模斜度,精度高,取小值,较高,较大的尺寸,取小值,形状复杂不易脱模取大值,收缩率大的取大值,壁厚较厚者取大值,型心面比型腔面小.,增强塑料宜取大,自润材料可取小.,塑件的壁厚,壁厚均匀原则,壁厚越厚,流程越长,壁厚决定塑件的使用性能:,强度,电气性能,尺寸稳定性,装配,壁厚一般为16mm,常用23mm,避免翘曲变形的设计,保持壁厚均匀,检查相交部分,逐渐改变壁厚,加强筋,加强筋的厚度必须小于相连接的壁厚,网格式加强筋须低于四周的高度.,有可能的情况下,螺丝柱需与本体连接.,支承面,小支承面的配合优于大支承面,以螺丝柱部位可得到高强度的可靠装配,圆角和孔,连接处以圆角过渡：,减小应力，改善流动，提高强度：0.51mm,孔间距不宜太小：用长圆孔加凸台,螺钉孔加倒角以容屑,铰链,铰链的截面不易过长,壁厚减薄过渡处以圆弧过渡,壁厚一般为0.20.4mm,材料：,注：融体流向必须是通过铰链部分，使其线性分子延主链折弯,塑件的尺寸精度,影响因素,成型材料,成型条件,塑件形状,模具结构：Gate,Flow,Direction,Parting,Tooling,存放条件,塑料机的发展,开炼机和压延机,螺杆挤出机(十九世纪后期),柱塞式注射成型机(二十世纪初),线式螺杆注射机(1956年),塑机的分类,混炼机械,捏合，开炼，密炼机,压铸机,挤出机,注射机,压延机：人造革，塑料薄膜等,吸塑机,吹塑机,注射机的结构组成,注射装置,塑化部件：螺杆，料筒和喷嘴,料斗，计量装置，传动装置，注射和移动油缸,合模装置,前后固定模板，移动模板，连接前后固定板用拉杆，合模油缸，移动油缸，连杆机构，调模装置，顶出装置,注射成型过程,Fill,Injection,Pack,Injection,Hold,Screw,Return,Decompression,Cooling,Time,Mold,Open,Ejector,Forward,Ejector,Back,Mold,Closes,注射机的基本参数,公称注射量,注射压力,注射速率,塑化能力,锁模力,合模装置的基本尺寸,模板尺寸，拉杆空间，模板最大开距，动模板的行程，模具最大小厚度,注射模分类,单分型面注射模具,双分型面注射模具,带有活动镶件的注射模具,横向分型轴芯注射模具,自动卸螺纹模具,定模顶出模具,无流道模具（热流道，绝热流道）,单分型面注射模具,双分型面注射模具,注射模典型结构,成型零部件,浇注系统,导向部分,分型抽芯机构,顶出装置,冷却，加热系统,排气系统,Leader Pin,Clamping Plate,Stationary Half,Moveable Half,Ejector Plate,Cavity,Sprue Bushing,The pathway for material to follow to get from the injection nozzle to the mold cavity.,Comprised of:,Sprue,Runner,Gate,Runner System,Use Balanced Runner Systems,Diameter(min)vs.Length(max),3/16”=6”long,5/16”=12”long,3/8”=15”long,Runners,Unbalanced,Balanced,Coldwell,Traps cold slugs formed at tip of injection nozzle,Keeps slugs from entering mold,Coldwell,Runners,Full Round,Modified,Trapezoidal,Trapezoidal,Half,Round,A runner is only as efficient as the largest full round runner drawn in its cross section,Sprue Bushings,Sizing,Draft(1.5-3.5 Per Side),Pullers&Coldwell,A sprue bushing is the entry port,for injecting resin into the mold,Undercut Ring,Ball Puller,Z Puller,Reverse Taper,Designed to pull the sprue from the sprue bushing when the mold is opened,Sprue Puller,浇口设计,流动的分布需均匀,开在最厚的部分，以便保持最大的保压,浇口应设计到熔体最后冷却的地方,注意玻纤排列方向的影响,浇口的类型,针点式浇口,潜伏式浇口,边缘浇口,扇形浇口,平缝式浇口（薄片浇口）,圆环形浇口,浇口的类型,轮輻式浇口,爪浇口,护耳式浇口,直浇口,浇口的类型,Tunnel/Sub,Edge,Pinpoint,Hot Manifolds,Hot Manifolds,Hot manifolds systems:,Provides heated passage to mold cavity,Allows 15%to 20%faster cycles,Eliminates sprue&runner scrap,Improves part quality,Reduces molded-in stress,Externally Heated Manifold,AIR GAP INSULATES MANIFOLD FROM PLATES,UNIFORM TEMPERATURE ALONG MELT CHANNEL,EXTERNALLY HEATED,UNRESTRICTED FLOW,LESS PRESSURE DROP,EASIER MAINTENANCE,Courtesy of,Hot,Manifolds,Heater,Probe,Melt,Channel,Cooling,Plug,Locator,Ring,Heater,Manifold,Pocket,Melt Channel,Heater,Cooling,INTERNALLY,HEATED,EXTERNALLY,HEATED,Hot Manifolds,Externally heated hot runner systems are recommended:,Reduce pressure drop,Reduce shear and thermal history,Prevent burn and brown streaks,Ease changes in color or material,Facilitate purging,Valve-Gated Hot Manifolds,CYLINDER,PISTON,VALVE PIN,SPRUE BUSHING,MANIFOLD,INSULATOR,INSULATING AIR GAP,NOZZLE HOUSING,NOZZLE TIP,NOZZLE HEATER,MANIFOLD PLATE,CAVITY PLATE,Hot Manifolds,Manifold sizing,Streamlining,Tip design,Stand-offs/insulation,Controls,Hot Manifolds,BALANCED,MANIFOLD,UNBALANCED,MANIFOLD,分型抽芯机构,手动侧向分型抽芯,机动侧向分型抽芯,弹簧，斜导柱，弯销，斜导槽，锲块，斜滑块,液压气动侧向分型抽芯,分型抽芯机构,模具模拟动画八,上一个,返回,分型抽芯机构,Cooling/Heating,Water is typically used to heat or cool mold,Uniform mold temperature is critical to:,Cycle time-Warpage control,Shrinkage-Dimensional control,Surface appearance-Stress control,Crystallinity-Sinks and voids,Weld lines-Blush,Glass/mineral-Jetting,Cold flow,Plan Water First,When Designing Mold,Cooling/Heating,Some critical details:,Depth/pitch/diameter,Turbulent flow,MTLs of construction,Design,Water Channels,Venting,Unfilled products .0005”-.001”,Filled Products .001”-.002”(over 10%),D1,The route by which air is allowed to escape from the cavity,Parting Line Vent,D1,Other Venting Techniques,Pin“flats”,Continuous vent,Blades,Porous metal,Vacuum,Overflow,Mold Surface,Ejector,Pin,Pin Venting,Ejection,Blades,Pins,Lifters,Stripper rings,Sleeves,Draft,Draft allows easier part ejection from tooling,Conventional:1 per side,With texture:(1+1.5 per.001”depth),No draft,Draft,Draw Direction,Tooling Metal Selection,Material Type,Homopolymers,and,Unfilled,Copolymers,Reinforced,Material,Steel,Type,P20,S7,H13,420,Tool Steel,Characteristics,Medium Alloy Mold Steel,Shock resisting tool steel,Hot work tool steel(Cr based),Stainless steel,Typical,Hardness,as,Finished,(Rockwell C),30-36 Rc,54-56Rc,50-52Rc,50-52Rc,模流分析(CAE),缺陷分析,Troubleshooting,缩痕,变形,毛邊,熔合线,银丝,喷纹,烧焦,缺陷分析,Troubleshooting,Burn marks:,Add vents,Reduce injection speed,Move gate location,缺陷分析,Troubleshooting,Sink marks:,Increase pack pressure or time,Reduce injection speed,Reduce rib to wall thickness ratio,缺陷分析,Troubleshooting,Stringing:,Reduce nozzle temperature,Use decompression,Use reverse taper nozzle,缺陷分析,Troubleshooting,White Spots:,Dry material,Reduce injection speed,Adjust melt temperature,