In the production process, dent is bad phenomenon in the highest frequency, the occurrence of plastic injection mould shrinkage during cooling, cooling the surface hardening first part is early, will have a bubble, the so-called dent, is part of the slow cooling of bubble contraction in to produce conspicuous concave.
Shrinkage materials are prone to dents. When you want to change the molding condition to eliminate the dent, should be set to shrink in the direction of setting conditions. Namely the mold temperature, the material cylinder temperature reduces, the injection pressure enhances, but should pay attention to this may cause the residual internal stress.
Because the indentation to inconspicuous as well, so, if not to affect the appearance, intentionally in the mold processing into corrosion appearance, such as striated and granular. Also, if the molding material is HIPS, to reduce the mold temperature to reduce the degree of finish is also effective. But these methods have occurred once the dent it is difficult to repair, polishing products.
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