11 - Microcellular Injection Molding

Abstract

Plastics have been produced as foams since their earliest development, with the objectives of attaining physical properties such as thermal insulation and light weight. Most mechanical properties, such as tensile strength, are significantly lower with the foamed version of a material. Recently, various microcellular foaming processes have been developed with the primary objectives of reducing material usage and increasing productivity with little or no loss in mechanical properties. Applications of microcellular foamed products range from structural and mechanical components in printers, to automotive fan shrouds and precision electrical components. Microcellular injection molding processes lead to reductions in weight, cycle times and molded-in stress, and improved dimensional stability. Thermoplastic foams can be produced with chemical foaming agents which release the foaming gas when the agent decomposes at a given temperature, or with physical foaming methods, which introduce the foaming agents directly into the polymer melt stream.