Shanghai Daoqin Plastics Co., Ltd.

plastics process in and shrinkage amount large small and processing plastics thermal expansion coefficient has 关, process thermal expansion coefficient is “模塑 shrinkage ”随 模塑 parts cooling shrinkage, parts and mold cavity cooling outer table/sheet 失 紧密接触 this cooling efficiency decline, parts cooling rear, parts shrinkage, shrinkage amount 取决于 various factors comprehensive function parts upper cooling most fast, ratio its it parts more hard 化, 接近模塑 parts in thick local type cooling most 远, formed is parts upper most rear hot amount local, 边角处 资 material solid rear, 随 接近 made parts in melt cooling, parts still 会继续 shrinkage, between can to mono cooling, its strong/high degree has 尖角处材 material strong/high degree high.          
made parts in plastics material cooling shrinkage, will separation cooling and cooling water relatively large 尖角间 versus for relatively low outer table/sheet toward inner 拉. this in injection molding parts outer table/sheet upper generate 凹痕. 凹痕 存 in 说明此处 模塑 shrinkage rate high its 周边部位 shrinkage. if parts in shrinkage high 于另一处, that 么模塑 parts generate warpage causes. inner 剩余应 force reduce parts impact strong/high degree and resistant temperature property can. has lower, adjustment process conditions can anti 止凹痕 发生. 例如, parts holding pressure process in, toward mold cavity outer plastics material, 以弥补模塑 shrinkage. large more 数情况 lower, gate ratio made parts its it local thin more, parts still very hot but also shrinkage 时, small gate already solid 化, solid rear, holding pressure for type inner parts 就不起 function.       
injection molding parts defect 特征, usually and outer table/sheet has 关, but also is plastics from mold outer table/sheet shrinkage 脱离形 formed    can can issues causes
1. mold cavity inner plastics 不足.
2.熔 melt temperature degree is high is low.
3. runner combined 理, gate small.
4. mold temperature is and plastics features versus 适应.
5. cooling stage/phase 时接触 plastics hot.
6. cooling 效果不 good, product demolding rear shrinkage.
7. product structure combined 理（ add strong/high high, thick, obvious thick thin 不一）    
弥补 methods
1. increase injection molding amount.
2. adjustment material temperature degree.
3. reduce mold outer table/sheet temperature degree.
4.设 method let product has cooling.
5.允许 情况 lower improvement product structure.
6. adjustment screw speed degree obtain positive screw surface speed degree.
7. according to use plastics features and product structure control mold temperature.
8.检查止流阀 is 否安装 positive 确, is non positive 常运行会引致 pressure 流失.
9.矫 positive runner anti pressure loss large; according to need, expand large dimensions.
10. ensure use positive 确 垫 material; increase screw toward front time; increase injection molding pressure; increase injection molding speed degree.   
包封 一, injection molding parts defect can easy in transparent injection molding parts gas 阱” inner to can in transparent plastics in, this and thick degree has 关, but also plastics shrinkage injection molding parts in 心而引起.    二, can can issues causes
1. plastics 未彻底 drying.
2. mold separation filling.
3.预塑 or injection speed degree fast.
4.止流阀 不 positive 常运行.
5. certain 特殊资 material application equipment production.  
弥补 methods 1. increase material amount.
2. reduce melt temperature degree.
3. increase injection molding pressure.
4. increase screw toward front time.
5.检查止逆阀 is 否裂开 or method as.
6.适当 reduce screw speed and increase large back pressure, or reduce injection speed degree.
7.应 according to plastics features improvement drying conditions, let plastics full drying.
8. reduce or increase injection molding speed degree. for non crystallization type plastics need increase 45% speed degree ）     products molding dimensions degree low    injection molding parts defect 特征
一﹐ injection molding process in weight dimensions ultra- 越 mold, injection molding machine, plastics combined production can force.   
二, can can issues causes
1. injection molding pressure unstable.
2. screw unstable.
3. injection molding machine amount small.
4.输入射 material inner plastics 不均.
5. use combined mold plastics product types.
6.射 material temperature degree or scope/range large.
7. injection speed degree （流 amount control ） unstable.
8.运 as time 变化, solvent liquid degree 不一致.
9.考虑 mold temperature, injection pressure, speed degree, time and holding pressure and other for product effect/influence.    
弥补 methods
1. use back pressure.
2.检查运 as time 不一致 property.
3.检查 has 无充足 cooling water material 斗喉以 maintain positive temperature degree.
4.检查 is 否错误 进 material setting.
5.检查 is poor or hot electrical 偶.
6.检查 is 否每次运 as has stability melt hot material.
7.检查回流 anti has 否泄露, has need 就进行 more 换.
8. ensure screw in 每次运 as 复回位置都 is stability more 于0.4mm变化.
9. selection combined mold plastics product types （ main/primary from shrink rate and machine strong/high degree 虑）
10.检查 and temperature degree control device use hot electrical is belongs to positive type type.
11.检查 liquid pressure system as is positive 常, temperature is high or low （25-60C 1
2.检查 injection molding machine injection molding amount and can force, rear and injection molding amount and small 时 注 plastics use amount ratio 拟.   
13. heavy new adjustment production process.