Solution for general defects of BMC molding.doc

Defects缺陷Root Causes原因Solutions解决方法Partial filling不完全填充Injection pressure too low射胶压力太低Material is not enough料尺太少Holding pressure too low保压太小Low fluidness of material原材料的流动性太差Raw material too hot原材料或模具温度过高，材料已硬化Missing venting排气不良Increase the injection pressure加大射胶压力Increase the shot size增加料量Increase holding pressure and time加大保压压力；延长保压时间Increase heating in barrel, cool sprue & mold加高炮筒；冷咀及模具的温度Reduce temperature in barrel, cool sprue & mold降低炮筒；冷咀及模具的温度。检查原料是否已硬化Set up the venting program改善模具的排气Damaging during mold release出模时产品损坏Cooking no finished产品未完全固化Internal stress in the parts产品存在内应力Undercut exists in the cavity模具有倒扣Increase the cooking time延长固化时间Reduce the injection pressure and holding pressure减小射胶及保压压力Check the mold检查模具The sprue is broken射咀堵塞Sprue no cook enough水口未完全固化，留在射咀里面Bad cooling in cold runner冷流道系统的冷却不良Unreasonable design for the sprue, no certainly step in the fault射咀设计不合理Increase the cooking time or temperature of mould延长固化时间或增加模具温度Check the cooling channel inside the cold runner检查冷流道的冷却水路Check the sprue design检查射咀设计The part stays on fixed side产品粘前模The part can stick on the colder side of mold通常情况下，产品容易留在温度较低的一边Material is not enough不够料Review the part & mold design重新审查产品结构及模具设计Adjust temperature in the mold调整模具温度Increase the shot size增加料量Take consider that whether the double eject is need考虑是否需要两边顶出The screw dont move back or unstable recharge螺杆无法后退或回料不稳定Too high back pressure背压太高Too low rotation of screw螺杆转速太慢Too low pressure in stuffer压料的压力太小Raw material hard in stuffer加料筒里面有硬料堵塞Viscosity of raw material is too high材料太粘Clearance between check ring & barrel is too small止回环与的炮筒之间的间隙过小Check ring broken止回环爆裂Adjust the back pressure调整背压Adjust rotation speed调整螺杆转速Increase the pressure in stuffer加大压料的压力Clean the stuffer清理料筒Review the raw material with RM supplier反馈至原材料供应商Double check the diameter of the check ring & barrel检查止回环与炮筒的内径尺寸Replace the check ring更换止回环Raw material leakage between mold & nozzle原料在射咀及唧咀之间泄漏Bad contact nozzle/mould射咀及唧咀配合得不好Check the centring of nozzle检查射咀及唧咀的对中性Check the radius of nozzle & sprue检查射咀及唧咀的RCheck the pressure of unit injection检查射台的压紧力Defects缺陷Root Causes原因Solutions解决方法Raw material too hot原材料太热Back pressure too high背压太高Barrel temperature too high炮筒温度太高Speed rotation too high螺杆转速太快Injection pressure & speed too high射胶压力及速度太高Reduce the back pressure减小背压Decrease the temperatures减低炮筒温度Reduce the rotation speed减低螺杆转速Reduce the injection pressure and speed减低射胶压力及速度Irregular dosing or cushion不正常的射胶量及残量Rotation screw too fast螺杆转速过快Back pressure too low背压太低Stuffer problem加料器有问题Raw material hard原材料已经硬化The screw or check ring is worn螺杆或止回环已经磨损Reduce the speed减低螺杆转速Increase the back pressure加大背压Check the stuffer 检查加料器Change the raw material检查原材料Change the screw & check ring更换螺杆或止回环Serious burrs in the mold严重披风Too much material料量过多The mould doesnt close模具锁得不够紧Injection pressure too high射胶压力太大Unreasonable venting design排气设计不良The clamping force is not enough锁模力不够Reduce the shot size减少料量Increase the closing pressure重新调整模厚，增加锁模力Reduce the injection/holding pressure and speed减小射胶保压压力及速度Correct the mold if possible or adjust the holding修正模具或调整保压Review the machine size by calculate the clamping重新计算机器的吨位是否合适Part with deformation产品变形Injection speed too slow射胶速度太低Cooking time too short固化时间太短Ejection problem-unbalance顶出不平衡Internal stress in the parts内应力太大Bad position of gate causes the unidirectional shrinkage or too much internal stress.水口位置不合理导致单向的收缩及内应力太大Part design-any deep opening section is exists.产品的结构-存在一些很深的开口Raw material (SMC compression moulding only)原材料不稳定，只要是SMCIncrease the injection speed增加射胶速度Increase the cooking time or mould temperatures延长保压时间或模具温度Review the ejection design重新审查顶出系统Reduce the injection/holding pressure & speed减小射胶保压压力及速度Take consider to changing the gate position or adding more gates, or change the pure injection process to injection/compression for reduce the internal stress and avoid the unidirectional shrinkage.考虑更改水口位置或者增加更多的水口，又或者将单纯的注射改成射压，减低内应力及单向收缩Review the part design and consider to use the cooling fixture重新审查产品的结构或者使用夹具定型Review the directionally of the glass fiber inside the raw material, it may causes the unidirectional shrinkage重新审查玻纤在材料里面的排布方向，它可能会导致单向收缩Defects缺陷Root Causes原因Solutions解决方法Material remains in the mold, especially in the mat surface模具粘料，特别是有纹面的地方The part didnt pack well.产品没有充填好Mold temperature too low.模温太低Bad release of the raw material.原材料的脱模性不好Increase holding pressure and time, the cushion is the must for improve this issue, the suggested cushion size for BMC injection moulding is 46mm, the minimum.增加保压压力及时间，残量是改善这个问题的必要条件，BMC注塑建议的残量为最小46mmIncrease the mold temperature.增加模具的温度Review the release agent with raw material supplier反馈至原材料供应商Knit lines熔接痕Raw material cure too fast.原材料固化太快Reduce the mould temperature.减低模具温度Increase the pressure or speed & barrel temperature增加注射压力及速度，以及炮筒温度Review the reaction temperature & curing speed of the raw material with supplier.与原材料供应商重新审查原料的反应温度及固化速度Porosities in part沙孔The cavity pressure is too low, the part didnt pack well.模腔压力太低，产品没有充填好Low fluidness of material.原材料流动性过低The material is too loose (soft), too many gas inside.原材料太松软，太多气体在里面Back pressure too low.背压太低Poor venting.排气不良Increase holding pressure and time, the cushion is the must for improve this issue and make it consistently, the suggested cushion size for BMC injection moulding is 46mm, the minimum.增加保压压力及时间，残量是改善这个问题的必要条件，BMC注塑建议的残量为最小46mmIncrease heating in barrel, cool sprue & mold.增加炮筒；冷流道及模具的温度Increase the back pressure (take case to the strength); increase heating in barrel or ask supplier to make the material a little solid (harder).增加背压(留意产品的强度)；增加炮筒温度及要求原料供应商将材料做硬一点Review the venting design.重新审查模具的排气设计Burn in part产品烧黑Poor venting or injection speed too fast, no enough time for the gas out.排气不良或者注射速度太快，模腔内的气体没有足够的时间跑掉Mould too hot.模温太高Review the venting design and slow down the injection speed, and the breath program.重新审查排气的设计及减低注射的速度，以及排气的动作Reduce the mould temperature.降低模具温度Aspect problems:wave & white marks / Lose polishing外观问题：波浪纹；白斑及不够光亮Mold temperature too high / low.模温过高或过低Mold polishing.模具抛光Injection speed is too slow射胶速度过低High humidity of raw material.原材料的湿度过高Adjust the mould temperature.调整模具温度Check the mold surface.检查模具表面Increase the injection speed.增加射胶速度Review the material with supplier.反馈至原材料供应商Bubbles-Incomplete curing起泡未完全固化Incomplete curing in some areas of the part (thick wall, deep hole).产品某些位置未完全固化(厚墙，深孔)Increase the curing time and mould temperature.延长固化时间及增加模具温度Review the design of heating system, take consider to adding some vertical heater beside the thick wall or inside the insert for the deep hole.重新审查发热系统的设计，考虑在厚墙及深孔的位置增加垂直的发热管Defects缺陷Root Causes原因Solutions解决方法Cracking;裂纹Shrink cracking;收缩裂纹Surface cracking.表面裂纹Damage during ejection phase.在顶出时损坏Flow line/knit problem.流动熔接痕问题Mould problem (undercut exists)模具问题，有倒扣Part design (big difference of wall thickness).产品设计(壁厚存在很大的段差)Excessive shrinkage.过度收缩Internal stress.内应力The raw material is too fresh.原料太新鲜Review the ejection design, make the part with enough ejector pins and be ejected balance.重新审查顶出的设计，确认顶针足够及顶出平衡Adjust the injection parameters (increase the injection speed & reduce the mold temperature; make sure the material didnt cure before reach the flow end. Change the changeover point of each injection phases, to let the material confluents as soon as possible after crossed the barriers).调整注塑参数(增加注射速度及降低模温，确保材料在完成注射前没有固化。调整每一段射胶的转换位置，让材料可以尽快地越过障碍并熔接在一起Check and modify the mould.检查并修正模具Review the part design, avoid the big difference of wall thickness or make the difference smoothly.重新审查产品设计，尽量避免大的壁厚段差，壁厚有段差的位置尽可能是平滑过渡Check with raw material supplier that if its possible to reduce the shrinkage rate.与原料供应商确认是否可以减小原料收缩Try to increase the mold & barrel temperature and reduce the injection & holding pressure, the retract process after holding & delay of gate cutting is the must for improve this issue, the purpose is to allow the material comes out from the cavity a little bit to low down the cavity pressure (only for the slight surface cracking).尝试增加模具及炮筒的温度，减小射胶及保压的压力，保压后的倒索及切刀延迟是改善这个问题的必要条件，目的是让模腔里面的材料倒流出来一点点以降低模腔内压力(只适用于轻微的表面裂纹)Place the raw material for some more time after made, before use.原料生产出来后多摆放一段时间再用Less strength of part产品强度不够(Continue.)Less strength of part(继续)产品强度不够The back pressure is too high and damaged the glass fiber so much.背压过高，对玻纤的破坏太厉害The sprue hole is smaller than the nozzle hole and damaged the glass fiber and caused the overheating.射咀孔的直径比唧咀孔的直径小，对玻纤造成破坏及产生过热的情况Unreasonable design for the runner.流道的设计不合理Review the strength requirement to the part.重新审查产品的强度要求Incomplete curing.固化不完整The cavity pressure is too low, the part didnt pack well.模腔压力过低，产品没有充填好This is a very important point in BMC injection moulding, big back pressure will damage the glass fiber a lot and reduce the strength. Normal back pressure for a BMC is between 2 to 4 BAR.这是BMC注塑的要点，大的背压会对材料里面的玻纤造成严重的破坏，通常情况下，背压应该为24 barModify the sprue hole; make sure its bigger than the nozzle hole at least 1mm.修正唧咀射咀孔或唧咀孔的直径，确保射咀孔的直径比唧咀孔的直径大至少1mmReview the runner design according to the “Calculation for Gate & Runner size” file.参照“Calculation for Gate & Runner size”文件重新审核流道的设计May be the part is not suitable to run with normal injection process (screw), take consider to change to use the plunger type injection machine, in order to avoid the damage to the fiber during screw rotating.可能产品不适合于用普通的螺杆式注塑机成型，考虑使用柱塞机进行成型Increase the mold temperature.加高模温Increase holding pressure and time, the cushion is the must for improve this issue and make it consistently, the suggested cushion size for BMC injection moulding is 46mm, the minimum.增加保压压力及时间，残量是改善这个问题的必要条件，BMC注塑建议的残量为最小46mmCOMPRESSION PROCESSPartial fillingLess material.Loss fitting in the shut off area of the mold, too many flash around the part.Modify the loading size of cavity.Double check the mold, the recommended clearance between cavity and core in the shut off area is 0.020.03mm/side.Porosity on blind areaLess material.Poor venting.Bad filling.Too many gases inside the raw material.Modify the loading size of cavity.Adjust the venting & mold closing process; add more ejector pins under these areas and