Effect of Sand Material Type on Heat Absorbing Properties of Mold in Expendable Pattern Casting Process of Aluminum Alloy Castings

The effect of sand material type on the heat absorbing properties of molds in the expendable pattern casting (EPC) process of aluminum alloy castings was investigated experimentally. The bulk densities and thermal conductivities of dry packed beds composed of several types of sand were measured. Because the true density of sands used in this study was higher than that of natural silica sand, the bulk density of the sand packed beds was also higher. The thermal conductivities of the packed beds of zircon sand and steel shot used in this study were almost the same as that of natural silica sand. The thermal conductivities of the dry packed beds composed of artificial sand were slightly smaller than that of the natural silica sand. Using test sands used in this study, an aluminum alloy plate was cast by the EPC process. The solidification time was obtained from the cooling curve. Compared to the solidification time for natural silica sand, the times for artificial sands were longer, while those for zircon sand and steel shot were shorter. Considering the interfacial resistance at the molten metal – sand mold interface, the solidification time and heat diffusivity showed relatively good correlation.