Molding the plastic mold sharp cooling fastest curing earlier than other parts

Molding the plastic mold sharp cooling fastest curing earlier than other parts near the molded thick portion at the center of the cooling surface furthest from the cavity, a plastic mold molded part of the last heat release, corners After curing of the material, as it approaches the center of the melt is cooled parts, molded parts will continue to shrink, the plane between the sharp corners can only get one side cooling, the strength of the plastic mold material without sharp corners at high intensity.

At the center of the plastic mold material parts of the cooling contraction, the degree of cooling the partially cooled and the corners between the larger inward surface of the relatively weak pull-up. Thus, the plastic mold injection of a dent produced on the surface. The existence here dent mold shrinkage rate of contraction in its surrounding area.

If the molding shrinkage in one place than another, plastic mold then the cause warpage molding. Will reduce the residual stresses mold molding of the impact strength and heat resistance. In some cases, adjustment of process conditions to avoid the generation of dents.

For example, the holding pressure of the molding process, plastic mold is injected into the cavity additional material to compensate for the molding shrinkage. In most cases, the gate is much thinner than other parts of the work piece, the molding is still hot and continues to shrink, the small gate has been cured, plastic mold after curing, pressure of the molding cavity is not work.