The new Kroehling Advanced Materials Foundry, home to the Virginia Tech Foundry Institute for Research and Education (VT-FIRE), officially opened in January 2011. The foundry has induction and resistance melting plus bonded sand, printed and investment molding. Patterns for investment casting are currently being made by pouring wax into silicone rubber/polyurethane molds or by 3D printing. Engineering students are designing complex components (structural and non-structural) and rapidly turning their designs into metal components by investment casting. The polymers used for 3D printing pose many challenges when used as investment casting patterns. During burn-out, printed polymers generate greater amounts of gas, compared to wax, and the complete removal of carbon created by the polymer decomposition requires higher burn-out temperatures and longer times at temperature. This paper describes our efforts at developing a standard practice for the use of 3D printed polymer patterns for investment casting.
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