Investment casting is now an integral part of the metal casting curriculum at Virginia Tech. Expendable pattern making (preparation of silicone rubber molds for wax patterns & 3D printing of polymers), investing (prime & back-up), wax/polymer burn-out, mold pre-heating, pouring and break-out are practiced in both the elementary and advanced metal casting laboratories. This paper discusses the specific processes being taught and practiced at the Kroehling Advanced Materials Foundry at Virginia Tech and highlights a variety of investment castings produced by Virginia Tech students from the Art, Architecture and Engineering Colleges.

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 investmtent casting are currently being made by pouring wax into silicone rubber 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. This paper describes our efforts at developing a standard practice for the use of 3D printed polymer patterns for investment casting.