Shanghai Daoqin Plastics Co., Ltd.

         in product production process in, product and gas is defect phenomenon in frequency rate most high, mold plastics in cooling 时发生体积 shrinkage, cooling separation surface hard 化, internal generate bubbles;

         谓凹痕就 is cooling slow separation in bubbles shrinkage direction generate 显眼 凹面; gas mold inner material from surface solid 化, for mold inner full 部容积 讲材 material versus for 不足, due to this causes generate true 空状态 孔, generally in products thick and material 口处.

         shrinkage property large material easy generate 凹痕. need molding conditions remove 凹痕时, setting conditions shrinkage small direction setting. mold temperature, material temperature degree reduce, injection shot pressure improve/increase, is attention/notes can can 会引起残余 internal stress.

        因 is 凹痕以不显眼 is good, therefore effect/influence appearance 时候, in mold upper processing formed 腐蚀 模样, 例如纹状, and other.

         if molding material is impact resistant property polystyrene (PS) HIPS(polystyrene (PS) PS types)时, use reduce mold temperature reduce light degree has 效果. is this methods has 凹痕发生, 想修理 abrasion light product has difficult.

         transparent product has gas formed issues, transparent product has gas has use upper 障碍且 product inner 也不宜看 to.

         due to water separation and material generate gas 孔, generally expand dispersion to products has separation, gas 孔 形状 generally relatively small.

        一, solution methods

        即时: improve/increase injection shot pressure, long injection shot holding pressure time, reduce material temperature degree and mold temperature degree, water separation and material 引起时应充 separation drying material, in generate 凹痕 方 strong/high made cooling.

         short 期: in generate 凹痕 方补 upper 流边. in generate 凹痕 方 材 material through has small 场 时, this separation add thick.

         long 期: 应彻底避免 design products thick degree 差异. easy generate add strong/high 筋, long 形状应尽 amount short. increase large gate, runner, separation runner, nozzle 孔. 改进排 gas.

        二, 参考事项

        1.  molding shrinkage property large material 凹痕也 large, polyethylene (PE) PE, polypropylene (PP) PP, make need micro add strong/high 筋, generate 凹痕.

        2. 当 temperature degree reduce to generate 凹痕时, if in mold cavity inner material also has pressure, 应该考虑 to generate 凹痕. in mold inner material in mold inner pressure pressure, what is 不一定.

        接近 gate separation pressure high, if material wide, is to 各 角落 pressure 传递, gate 同远离 gate pressure full pressure versus ratio versus very small 就不会 generate 凹痕, can to 不残留 internal force products.

        而部 separation material in has difficult 场 时, this has high pressure, other pressure reduce generate 凹痕. this separation high pressure 残留, is products internal force large. in 理想 状态 lower material temperature degree mold temperature degree upper rise, material flow property relatively good, and injection shot in pressure 状态也变 low.

        3.  in molding conditions 时, temperature degree, pressure, time combined 应预先 made as good table/sheet 格, 按顺序进行, can 早知道结果. time very long rear, pressure micro small 变化也容 easy 知道. attention/notes is: to temperature degree 变化时 结果, in injection material rear, and other temperature degree drop lower rear again production 时 结果.

        4. 判断 gas formed causes, need plastics product bubbles in mold opening is 瞬时出现 also is cooling rear 出现, if mold opening 时瞬时出现, more semi is material material issues, if is cooling rear 出现 则 belongs to mold or injection molding conditions issues.