Numerical Simulation of the Coinjection Molding Process

Coinjection molding comprises sequential or concurrent injection of two different but compatible polymer melts into a cavity in which the materials laminate and solidify. This innovative process offers the inherent flexibility of using the optimal properties of each material or modifying the properties of the molded part. The lack of previous experience and engineering know-how has made numerical analysis a useful tool for enhancing the engineers’ capability to handle this special process. This paper presents the methodology for analyzing the flow of two different polymer melts injected sequentially into a three-dimensional thin cavity. This study is distinct from numerous previous works dealing with single polymer melts typically used in the conventional injection molding process. As an illustration, a comparison between the predictions and experimental data for a co-injected part is presented, together with other relevant output showing the effect of different material properties on the outcome of the coinjection molding process.