Shanghai Daoqin Plastics Co., Ltd.

        随 我国人民生 active water 平 不断 improve/increase, small home appliances and 人护理 electronics product will in future year inner formed is hot 点. function 完善, resistant use, type 美观, use 方便舒适 high quality small home appliances product 呈现出 vast development outlook/prospects. precision injection molding parts as is small home appliances product important formed separation, its quality already related production high degree heavy 视, combined cost production appearance excellent 良, dimensions precision injection molding parts is in 眉睫 课题. however injection molding process in many factors can can products appearance defect, deformation, dimensions and other defect, how to can ensure in large amount production in stability made precision injection molding parts is need discussion issues.

        1 precision injection molding parts design requirements 首先, production precision injection molding parts mold must can combined molding high precision products requirements. usually, precision injection molding parts dimensions degree is SJ 1372-78 standards 3, 4 grade (precision grade), especially precision is 1, 2 grade (特殊 technology grade);而 mold manufacturing 允许公差应 versus 应 达 to standards 3, 4 grade or 1, 2 grade degree 1, type 芯, type and slip block and other using/adopting high hardness, high strength specialty manufacturing. mold inner also 应布置足够 cooling or add hot runner, ensure mold and dispersion or absorption hot amount, in production process in maintain mold temperature degree uniform, 恒定.

         its 次, molding precision injection molding parts can can selection shrinkage rate small, long stability property good material. usually, PS, ABS, AS, PMMA, PC, PPO(polyphenylene oxide (PPO)), PSU(polysulfone (PSU)) can molding 3, 4 grade degree products;PA series can molding 4 grade degree products;而POM, PP, PE, TPE(thermoplastic property elastomer) and other 不适宜 molding 4 grade above degree products. due to machine material filling or glass fiber reinforced plastics shrinkage rate low, dimensional stability high, by use molding high degree products. 例如, BAYER company PA6DurHhanRM2521/45因含 has 45% glass fiber (GF), its shrinkage rate 由PA6 0. 6%1.4% drop is 0.3%-0.7%, use material molding parts can to 3, 4 grade degree molding precision injection molding parts need precision injection molding machine and 适当 辅助 equipment: use electrical control liquid pressure or full electrical precision injection molding machine. this category of injection molding machine injection 行程灵敏 degree is 0.1nnn, injection speed rate and holding pressure pressure can to. 1%%, time control degree can 达0.1s, material temperature degree control degree can 达0.2~0.5. this 样, can setting injection and holding pressure more grade injection molding pressure, injection speed rate, injection and holding pressure time, ensure melt 充模历程 and setting process parameters separation combined. in injection - holding pressure methods upper, selection “行程转换 methods ” ratio selection “ time methods ” can more control injection amount. is ensure mold temperature degree 恒定, selection precision mold temperature adjustment machine.

         production precision injection molding parts 时, mono products cycle time heavy stability property separation important. if cycle time large (如10%), 就会导致 melt in material inner time 发生差异, mold cooling or add hot unstable, from 而引起 products dimensions 变化. therefore, precision injection molding mold design full production (products and material can 自动脱落 or use machine 械手取出), maintain cycle time stability.

         precision mold, combined Raw Materials, equipment formed precision injection molding parts molding 坚实基础. mold manufacturing formed rear, through more mold trial, positive mold defect, process parameters, can 准备投人 production: 2. 2 precision injection molding parts production non machine effect/influence factors analysis through mold trial, made combined products, 也确定 初步 process parameters, this 并不意味该 process parameters 就一定 suitable for large amount production, is dimensions 偏离, appearance or batch 间差异 and other issues 会经常出现 in production in. mold trial is in machine equipment and ring conditions lower, use batch Raw Materials in relatively short time inner 进行, process time short, versus for stability;而 large amount production 时, conditions can can molding 状态 波动并 effect/influence product quality, this need through research related non machine effect/influence factors, process property and can force causes, made solutions.

         non machine effect/influence factors has below/following several 方面: material 差异因 is plastics Raw Materials large more resin, filler, reinforcement material and (or) its it additives formed, make 同一厂家, grade resin molecular weight distribution or filler add ratio/proportion in batch 间差异. adjustment process parameters (material temperature, injection speed rate and other) can remove material effect/influence.

         injection molding machine if conditions 允许, production in most good use and mold trial same injection molding machine. however large more 数情况 lower, positive production and mold trial in different injection molding machine upper 进行. different injection molding machine can can for same injection speed rate, type pressure and other setting value performance 出响应差异. therefore true analysis and assessment this 差异, 提出指导 property 意见, combined injection molding machine.

         electrical pressure electrical electrical pressure 波动会直接引起 setting parameters value 变化. commonly used electrical high 峰期(白天) ratio low 谷期(午夜点至早7点) electrical pressure low 1030V. therefore, according to electrical pressure trend for process micro adjustment. for/regarding especially precision injection molding parts molding, 建议配备 large rate pressure electrical 源.

         ring temperature wet degree effect/influence Raw Materials use front, need separation dry, water separation gas 态形式进入而 reduce products property can, high wet ring in use remove wet machine. '' mold effect/influence in injection molding production in, certain resin 如POM, PA会 viscous mold type surface, 并逐渐积累形 formed material, mold 积垢, from effect/influence products appearance and dimensions. reduce product quality. therefore add strong/high for Raw Materials dry, improvement mold gas. use remove agent or ultra- 声波 equipment mold, decrease/reduce mold phenomenon.

         its it need 定时监测 injection molding machine as temperature degree, anti temperature 异常导致 liquid pressure system pressure unstable.

        3 process property research process and 否直接影啊 large amount production stability property.

         process 越敏感, production easy stability. 笔者针 for injection molding process in 4 main/primary factors ―― material temperature (A), injection speed rate (B), mold temperature degree (C) and holding pressure pressure (D) it for production stability property effect/influence. value attention/notes is, adjustment injection speed rate versus adjustment injection molding pressure, ensure injection speed rate can to setting value.

        首先, mold trial process parameters is 基准, according to table/sheet 1 solution/scheme, adjustment A, B, C, D high, low water 平, rear maintain its it parameters 不变, according to table/sheet 2 组 combined methods experiment/testing.

         experiment/testing formed rear, will classification separation: in T.艺赘数 setting is “ high water 平”时, quality good is +1 separation, 变化甚 micro or table/sheet 1工芝 parameters adjustment solution/scheme parameters water material temperature (A) injection speed rate (B) mold temperature degree (c) holding pressure pressure (D) low water 平(L)篼 water 平(H) table/sheet 2 process property research experiment/testing solution/scheme water 平注: table/sheet in table/sheet experiment/testing rear 顺序(1 -8), experiment/testing 顺序 安排 main/primary to rise high material temperature ratio reduce more fast is separation, quality bad is -1 separation; in process parameters setting is 2 versus 应 格子 in, use ￡(; value evaluation A, B, C, D各 factors 敏感程 degree (尤 is A, B, C, D in 任一): ￡(X)=J(H)-X(L). 显然, in evaluation certain factors 变动时, its it factors effect/influence by troubleshooting in outer. 例如, material temperature degree ￡(A)=(3+4+5+6)-(l+2+7+8). 若￡(X) value is +8, 说明此 process non stability;若￡(X) value is -8, 说明此T艺十 separation 敏感;若￡(X) value is +7~-7, need specific analysis 该I艺 parameters in high or low water 平 敏感 degree.

        确定 各丁艺 parameters degree rear (very less meanwhile 出现三 process parameters 都敏感 情况, mold trial made process has issues), can according to experiment/testing toward process parameters “ high water 平” or “ low water 平” direction adjustment. positive I艺 parameters 应运行24h above, 并每隔46h收集 products key/critical dimensions or parts heavy data, use statistics process control (SPC) methods forecast production process stability property.

        4 precision injection molding parts large amount production SPC methods and application SPC理论基础实际 upper, production in also in machine factors 波动. it for product quality effect/influence can use statistics methods forecast. SPC就 is use evaluation large amount production stability property. can utilizing statistics technology for production process stage/phase 进行监控, from to combined cost production excellent product 目.

         usually use can amount 化监测 for key/critical dimensions, parts heavy control or Cp, CPK evaluation injection molding stability property, SPC control false 定按规定 取样 methods to data X, ……共/V data, that 么: 以平均 value as is control in value, positive negative 3倍 standards 偏差(±3S,) as is control upper, lower 限(该 upper, lower 限应落 in specifications value upper lower 允许偏差 inner), control 图U由 can 见, 绿区工序 very stability, 黄区工序 stability, 红区工序 unstable; if certain amount value ultra- 出红区 control 线, can 初步判 is unstable, 应采取 measures adjustment to 绿, 黄区.

        L―平! value 土――绿区丨 type 腔2 type 腔1切腔2塑 parts s, s2 certain production “ and CPk(parts heavy)t table/sheet 5 table/sheet 明, use dimensions control 时, P, P2 and 匕: large 于1.33, Comparison Table 3 can 知工序足够 stability, process 波动导致 waste product rate small 于.

        00633%, 而P4 CP and (: small 于1., 显示工序 unstable, main/primary causes is parts degree requirements high. table/sheet 6 table/sheet 明, use parts heavy control 时S: and S: C, large 于2. 0, 显示工序潜 can non large, type CPK差别 relatively large, causes is melt in type 腔 充模 speed rate different, holding pressure stage/phase pressure 传递差异 make 注人两 type material amount in fine micro 差别. using/adopting light runner, improvement mold gas and other measures make MFR均衡 rear, can ensure type CPK value can to 1.33 above: 5结论 precision mold, excellent equipment, Raw Materials and stability T艺 parameters is precision injection molding parts stability production necessary conditions, SPC as is precision injection molding parts production process in types has process control 手段, can utilizing control and can force 指数CP, CPK assessment, forecast r序 can force. anti issues, decrease/reduce 浪费, ensure production excellent product.