Predicting the Incidence of Voids in the Injection Molding of Thick Ceramic Sections

A numerical method is used to calculate the temperature distributions and specific volumes of finite elements in a short cylindrical molding in order to find the time at which the pressure in the molten core reaches zero. The criterion for the formation of a void is that this event should precede the time needed for the center of the cylinder to solidify. The results of the prediction compare favorably with experiment. Further calculations are made in order to show the effects of material and machine parameters on the incidence of voids.