The Effect Of Dewaxing And Burnout Temperature In Black Mold Process For Copper Alloy Casting

Abstract

The main objective of this research is to investigate the effect of dewaxing and burnout temperature on the quality of copper alloy casting produced by a low cost block mold that has been developed. In the molding process, two types of silica sand which contain 97.9% silica (SiO2) and 97.2% silica have been used as a refractory material with POP served as a binder. Several mold formulations contained 15-40% plaster of paris (POP), 60-85% silica sand and 35% water had been developed and each formulation had been tested in the process of copper alloy casting. In the dewaxing process, the temperature of 170oC was found appropriate to be used as an initial mold heating temperature and complete wax burnout was effectively achieved with the temperature of 750oC for 5 hours. The insufficient burnout process has produced a defect casting with carbon residue, appeared as a black stain on the surface of the casting. Meanwhile, rapid initial heating had prevented the wax from flowing out smoothly thus, eroded the surface of the mold cavities. This had resulted in deteriorated cavity surface, hence a rough surface of the casting.