Rapid tooling of composite aluminium filled epoxy mould for injection moulding of polypropylene parts with small protruded features

Abstract

Abstract Rapid tooling evolved from rapid prototyping is a novel method for developing prototype tooling rapidly using various additive manufacturing techniques. Traditional injection moulding is unsuitable for low-volume production because of the high initial cost. This study is focused on a rapid tooling approach for producing an injection mould insert for the low-volume production of plastic components. A plastic injection mould insert is designed, developed using composite aluminium filled epoxy with minute protruded features and tested on a vertical injection moulding machine as a rapid tool for low-volume production of plastic components. The composite aluminium filled epoxy (CAFE) mould insert is prepared using a wax master from silicon rubber mould prepared using a stereolithography master. Experiments are performed to determine the optimum mixing ratio of epoxy: aluminium powder for making the composite aluminium filled epoxy injection mould. The mould insert prepared was tested for the injection of polypropylene components on a vertical injection moulding machine and analyzed for dimensional accuracy. The analysis of dimensional accuracy and viability of minute features on the injected parts shows promising results for up to 30 injected parts. The injection of parts after 30 pieces resulted in increasing mould erosion and pitting, causing mould damage at the 36th injection shot. The experimental finding supports the feasibility of using the composite aluminium filled epoxy injection mould for low-volume production of the parts; however, the surface finish is inferior. The life of the mould is expected to give better results with a higher surface finish. It is also exposed that using mould release agents improves the life of the composite aluminium-filled epoxy injection mould.