Numerical Simulation of the Investment Casting Process

Determining alloy shrinkage factors is very important for the investment casting process. Casting dimensions can be obtained from numerical simulations of heat transfer and deformation phenomena. The accuracy of the dimensional results depends on heat transfer results. In order to validate heat transfer models, temperature data were obtained during casting of aluminum alloy A356 in shell molds made of fused silica and a zircon prime coat. The airflow near mold surfaces was partially restricted by the geometrical features of the casting, sprue, gating, or support system. It was shown that values for heat transfer coefficients at air-mold interfaces must be determined based on natural convection regimes and critical length scales for each surface. Numerical simulations results for the temperature are in good agreement with experimental results.