Shanghai Daoqin Plastics Co., Ltd.

“凹痕” is due to gate rear or material injection local inner shrinkage formed. injection molding parts products surface generate or micro is injection molding parts molding process in 一 老 issues. generally is due to plastics products thick increase products shrinkage rate local increase generate, it can can in external 尖角附近 or thick 突变处, 如凸起, add strong/high or base/seat rear, has 时也会出现 in 一 不 Common 部位. generate 凹痕 根本 causes is material hot cold shrink, is thermoplastic property plastics thermal expansion coefficient versus high. and shrinkage degree 取决于 many factors, its in plastics property can, most large, most small temperature degree scope/range and mold cavity holding pressure pressure is most important factors. also has injection molding parts parts dimensions and 形状, and cooling speed degree and uniform property and other is effect/influence factors. plastics material 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 surface 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 separation type cooling most 远, formed is parts upper most rear hot amount separation, 边角处 材 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 degree relatively large 尖角间 versus for relatively low surface toward inner 拉. this 样, in injection molding parts parts surface 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 residual stress reduce parts impact strong/high degree and resistant temperature property can. has lower, adjustment process conditions can 避免凹痕 generate. 例如, in parts holding pressure process in, toward mold cavity outer plastics material, 以补偿模塑 shrinkage. large more 数情况 lower, gate ratio made parts its it separation thin more, in 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. semi crystallization plastics material parts shrinkage rate high, this make issues more heavy; non crystallization property material shrinkage relatively low, most large degree decrease small 凹痕; filling and reinforcement material, its shrinkage rate more low, generate can can property more small. thick injection molding parts parts cooling time long, generate relatively large shrinkage, therefore thick degree large is generate causes, design add attention/notes, need amount thick parts, method thick 壁不见, design formed 空心, thick parts slip degree to 公称壁 thick, use large 圆弧代替尖角, can remove or most large degree decrease light 尖角附近 generate 凹痕. China plastics packaging 网