Numerical Simulation Of Multi Material Injection Molding With Application To Gas Assisted And Co Ijection Molding PDF Download

Abstract: In co-injection molding process, two different polymer melts are sequentially injected into a mold to form a part with a skin/core structure. Co-injection molding can be used among other applications for recycling, improving barrier and electrical properties. The basic characteristics of a co-injection molded product depend on the properties of the skin and core layers, and the skin/core volume ratio. This thesis presents a study of the effect of molding parameters on material distribution and mechanical properties of co-injection molded plates. The plates were molded with polypropylene(PP) and thermoplastic olefin(TPO) as skin and core. Four molding parameters-injection velocity, skin and core temperature, and core percent-were varied. Core percent was the most significant factor influencing core breakthrough. After the injection molding process reached steady state, molded samples were collected and cut to measure the core volume ratio using an optical microscope. Mechanical properties, such as flexural and impact strength show a good correlation with the core content. This thesis also compares the experimental results to numerical simulations using Moldflow Plastic Insight. Results for our simple mold show a good agreement between experimentals and simulations.