Evaluation of 3D Printed Polymers for Investment Casting Expendable Patterns

Additive manufacturing (AM) is an ideal method for producing expendable patterns for investment casting because of the possibility of reducing lead times, the low cost and the ability to produce unique patterns that can be created without changing tooling. Five 3D Printed materials, nylon 11, thermosetting photopolymer, epoxy resin, acrylonitrile butadiene styrene (ABS) and polymethylmethacrylate (PMMA), were selected based on their use in the investment casting industry and their availability as 3D printed polymers. Three basic shapes with sharp corners, curved surfaces and thin sections were designed using computer-aided design (CAD) to test the materials' ability to perform. Material burnout tests were performed to determine decomposition temperature ranges and dilatometry tests were conducted to determine the thermal expansion of the materials. The information from these tests was used to design burnout procedures for molded samples. Finally, the materials were ranked based on their performance during the molded sample burnout tests. From the highest performing to the lowest performing, the material rankings were as follows: PMMA, epoxy resin, ABS, Nylon 11, thermosetting photopolymer.