Development of injection molding simulation algorithms that take into account segregation

Abstract

The quality of injection molded products is influenced by several factors: the geometry of the product, the polymer used, the mold, the technological parameters of processing and the injection molding machine itself. For this reason, modelling the process by computer is justified and widely used in the industry. Modelling, however, is complicated by the complex flow dynamic and thermal processes during injection molding, and the changes in the material structure of the polymer. Various fillers are used to modify the properties of the polymer, which is an additional challenge for simulation. Processing can cause variation in local filler content in the polymer, which influences several properties of the polymer, but available injection molding software cannot handle the distribution of fillers during the molding process yet, reducing the accuracy of simulations. In this project, we investigated the behavior of polypropylene filled with glass beads during injection molding. For the tests, we prepared mixtures of various filler contents and different bead sizes by extrusion. We also measured the effect of different injection molding parameters, and we examined the segregation of fillers. We modelled segregation numerically with Autodesk Moldflow, and calculated segregation from the results by discrete element modelling.