Shanghai Daoqin Plastics Co., Ltd.

         injection molding various defect and solution methods lower:

        一, crazing

         crazing is plastics products relatively Common types defect, generate main/primary causes is due to force deformation 致. main/primary has residual stress, external force and external ring generate force deformation.

        (-) residual stress crazing

         residual stress main/primary due to below/following types 情况, 即充填 剩, demolding launch and metal parts formed. as is in 充填 剩 情况 lower generate crazing, its solution methods main/primary can in below/following 几方面入手:

        (1) due to gate pressure loss most small, therefore, if crazing most main/primary generate in gate 附近, can 考虑改 use more distribution gate, gate and gate methods.

        (2) in ensure resin separation understanding, poor front lower, improve/increase resin temperature degree can reduce melt viscosity, high flow property, meanwhile can reduce injection pressure, decrease small force.

        (3) generally lower, mold temperature relatively low easy generate force, 应适当 improve/increase temperature degree. injection speed degree relatively high 时, make mold temperature low 一, can decrease low force generate.

        (4) injection and holding pressure time long generate force, will its shrink short or 进行Th次 holding pressure 切换效果 relatively good.

        (5) non crystallization property resin, 如AS resin, ABS resin, PMMA resin and other relatively crystallization property resin polyethylene (PE), polyoxymethylene (POM) and other easy generate residual stress, 应予以 attention/notes.

         demolding launch 时, due to demolding degree small, mold type and coarse 糙, make launch force large, generate force, has 时甚至 in launch 杆周围 generate whitening or phenomenon. need fine crazing generate 位置, can causes.

         in injection molding meanwhile metal parts 时, most easy generate force, but also easy in 经 一段 time rear generate crazing, 危害极 large. this main/primary is due to metal and resin thermal expansion coefficient versus 差悬殊 generate force, but also time 推移, force ultra- 逐渐 poor resin material strong/high degree generate cracks. is anti generate crazing, as is experience, thick 7 and metal parts outer general purpose type polystyrene (PS) basic upper 不适于宜 add parts, 而镶嵌 parts for nylon effect/influence most small. due to glass fiber reinforcement resin material thermal expansion coefficient relatively small, comparison combined parts.

         another, molding front for metal parts preheating, tool has relatively good 效果.

        (二) external force crazing

         this external force, main/primary is design combined 理而造 formed force in, especially is in 尖角处 more attention/notes.

        (三) external ring 境引起 crazing

         chemical product, 吸潮引起 water degradation, and recycled material more use make material property poor 化, generate crazing.