Reverse Solidification Path Methodology for Dewaxing Ceramic Shells in Investment Casting Process
Dewaxing of investment shells is the most critical step in the investment casting process. It defines the fate of casting because the surface and dimensional characteristics of the wax are transferred to the ceramic shell and so to the final casting. A novel route of dewaxing of investment shells through a modified thermal heating method and the effect of such thermal heating on investment shells has been investigated. The experiments have shown firstly the formation of a "dilatation gap" followed by the reversal of the solidification path, and both facilitate the management of thermal expansion related problems, resulting in smooth discharge of molten wax. The shells made by this methodology of Reversed Solidification Path Dewaxing (RSPD) enable production with low rejection rates. The investment has been shown to be of high strength, sustaining thermal shock of more than one casting trial. The process can therefore be of great industrial importance pertaining to cost and energy efficiency, reduced defects, and high production rates.