A framework for analyzing energy efficient injection-molding die design

A significant part of the development of electronics products is the design of injection-molded thermoplastic parts ranging from chassis panels and enclosures to connectors. While much effort has been spent on analyzing the end-of-life issues associated with thermoplastic parts, such as disassembly, separation, and recycling, a primary driver for design-for-environment of plastic parts is the energy expended in the forming process. Traditional part design and process parameter selection, which is performed with the goal of minimizing process cycle time, often overlooks environmental issues such as energy efficiency. This paper analyzes the influence of component and mold design decisions as well as process parameters selection on the process energy efficiency through a framework that integrates a 3D solid modeling environment, numerical analysis of the filling and post-filling behavior, and an energy-based process model. The process model that is presented describes the modes of energy utilization in injection molding processes as they relate to design-for-environment concerns. Case studies are performed on a center-gated plastic disk, and a small plastic enclosure to illustrate the use of this framework.