Fluid-structure interaction model to predict deformation of mold cores in injection molding filling stage

Abstract

In the present study, a numerical model of the injection molding filling stage was developed by combining non-Newtonian behavior, heat transfer, and thermo-elastic behavior in order to precisely predict mold deformation. In general, local deformation of an injection mold can be caused by two critical factors – elastic compression induced by the plastic melt and thermal expansion due to rapid heat transfer from the plastic melt. As severe mold deformation lowers the dimensional accuracy of the molded product or results in failure of the injection mold, the accurate prediction of mold deformation is critical to the design and manufacture of precision injection mold. In this regard, a numerical model considering the relevant physical behavior was developed and applied to a center-gated disc model. Both the melt flow behavior and effect of heat transfer inside the mold cavity were investigated, which subsequently revealed that the dominant influence is that of thermal expansion due to heat transfer.