Numerical simulation of the co-injection molding process

During the past decade, Computer-Aided-Engineering (CAE) analyses have become useful tools for polymer processing, especially in the area of injection molding and its innovative derivatives such as co-injection molding. For the latter, since there is not much previous experience to follow and the engineering know-how has yet to be established, CAE analysis becomes even more important. This paper presents the methodology for analyzing the flow dynamics and heat transfer of the co-injection molding process when two dissimilar but compatible polymer melts are injected sequentially into a three-dimensional thin cavity in which the polymers laminate and solidify. It also discusses how this work handles two different materials; that is distinct from numerous previous works dealing with single polymer melts typically used in the conventional injection molding process. With the aid of the simulation, one can learn and evaluate the design, processing, and materials selection numerically, thereby eliminating unnecessary molding trials which are costly and time consuming. As an illustration, this paper presents a comparison between the predicted result and a real part in terms of spatial distribution of two dissimilar materials injected at different times, together with other relevant output showing the effect of different material viscosities on the outcome of the co-injection molding process.