Shanghai Daoqin Plastics Co., Ltd.

         injection molding conditions 不一致 or as 不当

         injection molding 时, temperature degree, pressure and time and other process parameters, must according to process requirements control, especially is types parts molding cycle must 一致, can 随意变动. if injection pressure low, holding pressure time short, mold temperature low or non-uniform, material and nozzle temperature degree high, parts cooling 不足, 都会导致塑 parts dimensions unstable.

         generally lower, using/adopting relatively high injection pressure and injection speed degree, 适当延 long and holding pressure time, improve/increase mold temperature and material temperature, has 利克服 dimensions unstable fault/failure.

         if parts molding rear outer type dimensions large requirements dimensions, 应适当 reduce injection pressure and material temperature degree, improve/increase mold temperature degree, shrink short time, decrease small gate 截面积, from improve/increase parts shrinkage rate.

        若 molding rear parts dimensions small requirements dimensions, 则应采取 and versus molding conditions.

         value attention/notes is, ring temperature degree for parts molding dimensions 波动也 has effect/influence, according to external ring 境 变化 and adjustment equipment and mold process temperature degree.

         molding raw materials selection 不当

         molding raw materials shrinkage rate for parts dimensions degree effect/influence very large. if molding equipment and mold degree very high, molding raw materials shrinkage rate very large, very difficult ensure parts dimensions degree. generally lower, molding raw materials shrinkage rate large, parts dimensions degree difficult ensure. therefore, in selection molding resin 时, must separation raw materials molding rear shrinkage rate for parts dimensions degree effect/influence. for/regarding selection raw materials, its shrinkage rate scope/range can large parts dimensions degree requirements.

        应 attention/notes various resin shrinkage rate relatively large, according to resin crystallization degree analysis. usually, crystallization type and semi crystallization type resin shrinkage rate ratio non crystallization type resin large, but also shrinkage rate scope/range comparison large, and for 应 塑 parts molding rear generate shrinkage rate 波动也 comparison large; for/regarding crystallization type resin, crystallization degree high, separation 子体积 shrink small, parts shrinkage large, resin large small for shrinkage rate has effect/influence, small, separation 子间 空隙 small, parts shrinkage relatively small, parts impact strong/high degree comparison high.

         in addition, if molding raw materials pellets large small 不均, drying defect, recycled material and new material mixed combined non-uniform, raw materials property can different, 也会引起塑 parts molding dimensions 波动.

         mold fault/failure

         mold structure design and manufacturing degree effect/influence to parts dimensions degree, in molding process in, mold rigid property or mold cavity inner molding pressure high, make mold generate deformation, 就肝造 formed parts molding dimensions unstable.

         if mold and sleeve/set 间 配 combined due to manufacturing degree or abrasion loss more ultra- 差, make parts molding dimensions degree decline.

         if molding raw materials inner has hard filler or glass fiber reinforcement material mold cavity heavy abrasion loss, or using/adopting more molding 时, type has and gate, runner and other and material balanced defect and other causes generate 充模不一致, 也都会引起 dimensions 波动.

         therefore, in design mold 时, design mold strong/high degree and rigid property, control processing degree, mold type material use wear resistant material, type surface most good hot and cold hard 化处理. parts dimensions degree requirements very high 时, most good using/adopting more structure 形式, is ensure parts molding degree, must in mold upper 设置一 series ensure mold degree plant/unit, mold made as cost very high.

        当塑 parts 出现偏 thick 误差时, 往往也 is mold fault/failure formed. if is in 一模一腔 conditions lower parts thick generate thick 误差, generally is due to mold 安装误差 and defect mold cavity and type versus for 位置偏移. 此时, for/regarding that thick dimensions requirements very 精确 塑 parts, can 仅靠导柱 and sleeve/set 定位, must increase other plant/unit.

         if is in more conditions lower generate thick 误差, generally lower, molding 开始时误差 relatively small, 但连续运转 rear 误差逐渐变 large, this main/primary is due to mold cavity and type 芯间 误差造 formed, especially is using/adopting hot runner molding most easy generate this type of phenomenon. for 此, can in mold inner temperature degree very small di cooling 回路. if is molding thin type container, can using/adopting type 芯, type and mold cavity must 同心.

         in addition, in made as mold 时, is 便于修模, generally is 习惯于 will type ratio requirements dimensions small 一, type ratio requirements dimensions large 一, 留出一定 修模余 amount. parts molding inner small outer 径时, 芯销应做 large 一, this is due to molding 孔处塑 parts shrinkage is large its it 部位, but also toward direction shrinkage. 反之, parts molding inner 径接近于 outer 径时, can small 一.

         equipment fault/failure

         if molding equipment 塑化容 amount 不足, add material system material unstable, screw speed unstable, function 失常, liquid pressure system 止回阀失灵, temperature degree control system hot electrical bad, add hot device and other, 都会导致塑 parts molding dimensions unstable. this fault/failure need rear can 采取针 for property measures troubleshooting.

         testing methods or conditions 不一致

         if 测定塑 parts dimensions methods, time, temperature degree different, dimensions has very large 差异. its in temperature degree conditions for testing effect/influence most large, this is is plastics thermal expansion coefficient need ratio metal large industrial 10倍. therefore, must using/adopting standards methods and temperature degree conditions 测定塑 parts structure dimensions, and parts must separation cooling type rear can 进行测 amount. generally parts in demolding 式10 small inner dimensions is very large, 24 small basic type.