Production of microcellular lightweight components with improved surface finish by technology combination: A review

Abstract

Microcellular Injection Molding (MIM) is a variant of injection molding technology used to manufacture plastic components, with a cellular structure and reduced weight. However, this technology is characterized for producing components with a poor surface finish and impacted structural integrity. To improve the molded surface appearance, the MIM process conditions have been thoroughly studied, nevertheless, some marks are often noticeable. For this reason, the combination of MIM with decorative technologies enables components with high surface finish, as well as, decorative and functional properties, among other benefits. Since the development of the technology surface improvement has been the focus of many research articles and recently, supported by the progress in machinery, technology integration has emerged as a solution. This review aims to expose the main advantages, disadvantages, and methods for surface improvement of MIM molded components. The key modifications and requirements for the tooling system as the supercritical fluid unit, the fuse, and mold modifications are discussed. The advantages of integration of these different processes with MIM technology are further described and a review of the progress so far is addressed as well as the incorporation of numerical simulation for the MIM components production. For that, technology integration of two-shot injection molding (2 K Shot), In-Mold Decoration (IMD), In-Mold Labeling (IML), and In-Mold Electronics (IME), which represent the biggest integration potential with MIM are examined.