Shanghai Daoqin Plastics Co., Ltd.

         issues 描述: production product 发脆, is 什么 causes?

         causes analysis:

         products in internal stress in heavy effect/influence products force property and use property can, due to products internal stress in and distribution 不均, products in use process in 会发生 cracks.

         in injection molding products in, local force is different, products deformation degree will 决定于应 force distribution.

         products in cooling in temperature degree degree, shrinkage generate force.

         melt temperature degree relatively low mold 时, mold cavity melt speed cooling solid 化, is separation 子链段 by “冻结”. due to solid polymer 层, thermally conductive property very 差, in products thick degree direction upper generate relatively large temperature degree degree.

         products 心部凝 solid versus slow, 以致于当 gate 封闭时, products in melt mono also solid, this injection molding machine also method for cooling shrinkage 进行补 material.

         this products internal shrinkage function and hard function direction is versus 反;心部处于静态 tensile table/sheet 层则处于静态 pressure shrink.

         if in gate front mold cavity pressure, has improve/increase products density, remove cooling temperature degree force, is in gate 附近会 generate relatively large force in.

        由此看 thermoplastic property polymer in molding 时, inner pressure large holding pressure time long, has temperature degree generate shrinkage force decrease small 反之会 make pressure shrink force increase large.

         improvement countermeasures:

         increase mold temperature, reduce injection, holding pressure pressure, holding pressure time. can in product in rear 进行“ hot water 浴”, remove 残存应 force.