Design and Manufacturing of Modern Injection Moulding Tools Utilizing Stereolithography

Abstract

Traditional steel tools for injection moulding are complex and expensive. Studies have suggested short run moulds can be made cost-efficiently with stereolithography (SLA). Technology company Formlabs recommends their material Rigid 10K for the purpose. However, available literature does not strictly confirm the usefulness of printed moulds for real-world industrial use, since very simple moulds have been described. Limitations in the printing process, as well as the mechanical and thermal properties of SLA resin determine possible use cases. To better understand their potential, SLA moulds from Rigid 10K were investigated experimentally and computationally. Components were produced from PC/ABS with an SLA and a steel tool, and results were compared. The resin was confirmed to print dimensionally accurately, with sufficient mechanical strength. The SLA mould produced 80 parts, with detail and surface quality comparable to production from the traditional steel tool. Resin moulded parts were within specified dimensions, but showed more sink marks and flashing than steel moulded parts. The thermally insulating nature of SLA resin proved challenging for injection moulding, causing long cycle times and quality issues. Heat flow simulations showed that cooling channels do not improve heat flow in printed moulds significantly. Moulds from Rigid 10K are brittle and break easily, especially in areas of high thermal stress.