Shanghai Daoqin Plastics Co., Ltd.

         warpage deformation is injection molding products 形状发生畸变而 warpage 不平, made parts 形状精 degree requirements, it is injection design and injection production in Common relatively difficult solution products defect 之一.

        随 plastics industrial development, especially is electronics industry development, for plastics products appearance and use property can requirements 越 越 high. 如笔记本 and upper electrical 脑, thin machine and other housing/shell made parts, warpage deformation degree already as is product quality important indicators 之一, 越 越受 to mold design 者 关注 and heavy 视. in design stage/phase forecast plastics parts can can generate warpage causes, optimization design, decrease small product warpage deformation, to product design degree requirements.

        1, warpage deformation generate causes

         warpage deformation is products in injection process process in, force and shrinkage non-uniform generate. demolding defect, cooling 不足, made parts and strong/high degree 不宜, mold design and process parameters and other make parts 发生曲变.

         mold temperature 不匀, parts internal temperature degree non-uniform.

        塑 parts thick and cooling non-uniform, shrinkage 差异.

        塑 parts thick toward cold pressure and cooling speed 差.

        塑 parts ejection temperature degree high or ejection force 不匀.

        塑 parts 形状不当, tool has bending or for 称 形状.

         mold degree defect, 定位不 can 靠, make parts easy warpage deformation.

        进 material 口位置不当, injection process parameters 不佳, make shrinkage direction property obvious, shrinkage non-uniform.

         flow direction and 垂直于 flow direction separation orientation property 差异, make shrinkage rate different.

        凸凹模壁 thick toward for cooling, cooling time 不足, demolding rear cooling 不当.

        2, mold structure for injection molding parts warpage deformation effect/influence

         in mold design 方面, effect/influence parts warpage deformation factors main/primary has large system, separation is system, cooling system and ejection system and other.

         gate design

         injection molding gate is 整 浇注 system key/critical separation, it 位置, and gate amount effect/influence material in mold type inner 填流状态, plastics solid 化, shrinkage and internal stress 异变. commonly used gate type type has gate, gate, 潜伏式 gate, gate, gate and film type gate and other.

         gate selection make plastics flow most short. flow 距离越 long, internal flow and external 冻结层 between flow increase, this 样冻结层 and in flow between flow and shrink internal stress large, parts deformation 也随之 increase large;

        反之, flow 距离越 short, from gate to made parts flow flow time short, 充模时冻结层 thick degree decrease thin, internal stress reduce, warpage deformation therefore decrease small.

        如 precision thin relatively large parts, use in gate or 一 侧 gate, toward shrinkage rate large toward shrinkage rate, molding rear parts generate relatively large deformation;若改 use more gate or film type gate, can has anti warpage deformation, therefore design must flow ratio 计算校核.

        当 using/adopting gate molding 时, due to plastics shrinkage toward property, gate 位置, amount for parts deformation degree has very large effect/influence.

         for 扁平箱形塑 parts in different gate distribution experiment/testing: using/adopting 15% glass fiber reinforcement PA66, weight is 1450g parts, 沿四周壁 flow direction upper has many add strong/high 肋. using/adopting basic same process parameters. gate methods: (a)直 gate, (b)5~4 点 gate, (c)9~8 点 gate. experiment/testing 结果, 按b设置 gate tool has most good 效果, meet/satisfy design requirements. 按c design gate ratio gate also 差, warpage deformation amount ultra- 出 design requirements 3.6~5.2mm.

         more gate can make plastics flow ratio (L/t) shrink short, from make inner material density and shrinkage more uniform. meanwhile, parts can in relatively small injection pressure lower mold cavity, decrease/reduce plastics separation orientation toward, reduce internal stress, decrease/reduce parts deformation.

         cooling system design

         in injection process in, parts cooling speed degree non-uniform will formed parts shrinkage non-uniform, this type of shrinkage 差别导致 bending force generate make parts warpage.

        如 precision 扁平状 relatively large housing/shell parts mold type 腔, type temperature degree versus large, cold mold cavity melt very fast cooling lower, 而贴近 hot mold cavity material 层则会继续 shrinkage, shrinkage non-uniform will make parts warpage. therefore, injection molding cooling system design 应严格 control type 芯, type temperature degree balanced.

         for precision 扁平状塑 housing/shell parts, molding shrinkage relatively large easy deformation material, production experiment/testing table/sheet 明, temperature 差不宜 ultra- 5°~8°.

         its 次, also 应考虑塑 parts temperature degree 一致, maintain type 芯, type 腔各处 temperature degree uniform 一致, make parts cooling speed degree 均衡, shrinkage uniform, has anti deformation generate. cooling system design in 理论计算 基础 upper, 应经严格 process mold trial 确定. therefore, mold upper cooling water 孔 设置至关 important.

         tube/pipe type surface 距离确定 rear, can can make cooling water between small, necessary using/adopting hydrophobic 密不均 排列形式, material temperature high cooling water 孔排密一, material temperature low cooling water dilute hydrophobic 一, 以维持 cooling speed degree basic same. meanwhile, due to cooling temperature degree cooling water long degree increase upper rise, cooling water long degree long.

         ejection machine design

         ejection machine design 也直接 effect/influence parts deformation. if ejection machine 构布置不 balanced, formed ejection force 不均衡而 make parts deformation. therefore, in design ejection machine 构时应 force and demolding retardant force versus balanced. 顶杆 截面积不宜太 small, anti parts mono 位面积受 force large generate deformation.

        顶杆 布置应尽 amount demolding retardant force large 部位. for/regarding precision 扁平状塑 housing/shell parts, can can more 设顶杆以 decrease/reduce parts deformation, using/adopting demolding and parts sheet/plate demolding versus combined composite/compounding demolding machine 构.

         use soft plastics production large type deep thin 壁 塑 parts 时, due to demolding retardant force relatively large, material also relatively soft, if full using/adopting machine ejection methods, will make parts generate deformation, use more parts combined or gas (liquid) pressure and machine ejection versus combined methods 效果会 more good.

        3, cooling and warpage deformation

        熔 melt plastics in injection pressure function lower, mold type in type inner cooling, solid. in this process in, temperature degree, pressure, speed degree versus combined function, for parts quality generate relatively large effect/influence.

         relatively high pressure and speed generate high 剪切应 force, 引起平行于 flow direction and 垂直于 flow direction separation orientation 差异, formed parts relatively large internal stress. temperature degree for warpage deformation effect/influence main/primary in below/following several 方面:

        塑 parts inner outer surface temperature 差会引起 hot force and hot deformation;

        塑 parts different between temperature degree 差引起 non-uniform shrinkage;

         different temperature degree 状态会 effect/influence plastics parts shrinkage rate.

         therefore, control injection process parameters is decrease/reduce warpage deformation important 手段.

        4, made parts shrinkage and warpage deformation

         injection molding parts warpage deformation causes in parts non-uniform shrinkage. for warpage deformation analysis 而言, shrinkage 本身并不 important, important is shrinkage 差异. in injection molding process in, material in injection stage/phase due to polymer separation flow direction make plastics in flow direction upper shrinkage rate ratio direction shrinkage rate large, make injection molding parts generate warpage deformation.

         generally uniform shrinkage plastics parts upper 变化, has non-uniform shrinkage 才会引起 warpage deformation. crystallization type plastics in flow direction and direction upper shrinkage rate relatively non crystallization type plastics large, but also its shrinkage rate relatively non crystallization type plastics large. therefore, crystallization type plastics parts warpage deformation toward relatively non crystallization type plastics large more.

        5, hot force and warpage deformation

         in injection molding process in, hot force is warpage deformation important factors, due to hot force for made parts warpage deformation effect/influence non complex, mold design usually injection molding CAE soft parts analysis and forecast.

        6, summary

         effect/influence precision thin plastics made parts warpage deformation factors has very more, mold structure, plastics material hot physical properties and injection molding process process parameters for made parts warpage deformation has different degree effect/influence. therefore, for made parts warpage deformation mechanism experiment/testing research must focus/key point comprehensive 考虑诸 more factors.