Injection molding of ribbed plastic plates with a superplastic Zn–22% Al sheet

Abstract

AbstractThis article presents the development of a hybrid process combining the forming of a superplastic zinc–aluminum sheet with injection molding. The product is a plastic part covered with a superplastic zinc–aluminum layer used mainly for electromagnetic interference (EMI) shielding. This hybrid process involves not only molding a plastic plate, but also forming a superplastic zinc–aluminum sheet with features such as ribs. This research observes the process of filling the cavity and forming the superplastic sheet with the aid of short‐shot experiments. By understanding the molding and forming process, guidelines for process control will be derived. This research further investigates the moldability of SIM systems. To make satisfactory parts, sheet thickness, melt temperature, injection parameters, and other process parameters determine the “moldability” of a specific system. The first part of the moldability study is to identify the relative importance of these process parameters. Results show that melt temperature and injection pressure are the two most critical parameters. The second part of this moldability study is to develop the moldability diagrams based on the molding area on the plane of these two key parameters. Moldability diagrams are employed to evaluate the effects of sheet thicknesses and melt inlets. It is found that a thick sheet, high melt temperature, and an inlet providing short flow length improve moldability. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 216–225, 2001