Shanghai Daoqin Plastics Co., Ltd.

injection molding processing in shrinkage? => parts shrinkage can is is dimensions upper shrink decrease.
can separation is below/following injection molding parts shrinkage 形态:

1. uniform shrinkage parts generate deformation 而改变 its 形状, is relatively small already.

2. shrinkage 不平均 工 parts generate deformation and its 形状, 不 变 relatively small already.
　

何谓 warpage?
当　 internal stress （因 shrinkage 不均）　＞　材 material rigid degree   => generate warpage

若塑 parts non-uniform shrinkage, 往往造 formed internal stress (internal stress) distribution 不均. 若此应 force ultra- 塑 parts rigid degree (stiffness), will formed parts warpage (warpage) and deformation (distortion), effect/influence parts dimensions property (dimensional stability).

shrinkage 不均四 large causes:

1. melt temperature degree different: melt temperature degree high shrinkage amount large

2. cooling speed degree different (晶质材 material)(asymmetric shrinkage):
causes: cooling speed degree fast < cooling speed degree slow (causes: cooling speed degree slow separation has time 排列, therefore shrinkage amount large)

3. melt toward different (non 晶质材 material)(anisotropy): 简而 说沿流 toward tensile internal stress large, shrinkage amount large. plastics in process in due to flow toward (flow orientation) causes, make separation 子链发生配 toward phenomenon. by toward polymer/macromolecule in flow direction and flow direction to tensile (stretch)情形各异, make shrinkage is has different. is direction shrinkage property (directional shrinkage). generally 而言, flow direction shrinkage rate (in-flow shrinkage) relatively flow shrinkage rate (cross-flowshrinkage) is high. this is is flow direction plastics polymer/macromolecule by 伸张 情形 relatively heavy, 恢复未伸张状态 trend relatively large. due to flow toward formed shrinkage phenomenon 往往造 formed parts warpage deformation. therefore can dispersion separation toward property will has shrinkage uniform property, decrease/reduce direction shrinkage formed warpage deformation 4. dimensions different (differential thermal strain): simple dimensions large shrinkage amount large

due to design 引发 翘区:

肉 thick (wall thickness) large small

肉 thick relatively thick 区域, cooling and holding pressure relatively is difficult, cooling time relatively long, holding pressure relatively 差. in demolding rear still maintain local high temperature, cooling. therefore in local thick relatively thick 处, 如肋(rib), easy has local shrinkage formed parts generate 凹痕(sink mark) phenomenon 发生. therefore for/regarding has parts 变化 塑 parts, 进浇位置 selection in relatively thick can has holding pressure, make parts 处发生 solid 化, still can 顺利传递 holding pressure pressure, improvement shrinkage phenomenon.

肉 thick 变化(wall thickness variation)

塑 parts thick uniform improvement shrinkage. parts thick distribution 不均, 应考虑 due to different cooling holding pressure 效果 导致 shrinkage is 否会引起塑 parts warpage deformation, and in thick 渡区域(wall thickness transition regions)造 formed force in (stress concentration) issues

肉 thick 渡区域(缓冲区域) internal stress in phenomenon formed short 期(short term) or long 期(long term) warpage issues, reduce parts mechanical properties (mechanical performance) and other disadvantages. parts can 引入补 strong/high 肋(reinforcing rib) strong/high structure strong/high degree decrease/reduce shrinkage. and parts 壁接触部份应 large to decrease force in (stress concentration) issues, flow retardant force;但亦应 attention/notes can can 引发之凹痕(sink mark) issues. generally 而言, large small plastics shrinkage features effect/influence, in strong/high degree rigid degree lower, can utilizing 掏空(core out) methods decrease/reduce parts thick, has decrease/reduce shrinkage.

molding conditions and deformation
　

as is and deformation has molding conditions must especially attention/notes is injection and holding pressure time ﹑ cooling time ﹑ injection speed degree ﹑ mold temperature degree.
　

1. injection and holding pressure time
injection and holding pressure and time need design long gate time. if ratio gate time short ﹐则 has deformation increase large.
　

2. cooling time
generally 而言﹐延 long cooling time make deformation decrease small.
　

3. injection speed degree
according to molding product different ﹐ has injection speed degree fast deformation small ﹐ has versus 反﹐ injection speed degree slow deformation small. in molding in ﹐ need through injection speed degree deformation most small conditions.
　

4. mold temperature degree
mold temperature degree low molding product deformation small. is ﹐ if molding product use temperature degree high ﹐ has 时则会 generate rear shrinkage deformation or dimensions issues. mold temperature degree need according to this factors comprehensive 考虑决定.