Experimental and Numerical Analysis on Core Deflection during Wax Injection

As the large thin-walled and hollow investment casting is widely used, control of core deflection during wax injection becomes increasingly important. Core deflection during wax injection can cause wall thickness to exceed tolerance in final cast part. This paper presents the numerical and experimental study on the core deflection of a thin-walled hollow wax pattern. The predicted deflection displacements were compared with the experimental data to find good agreement. The mechanism of core deflection was found through 3D numerical analysis. The packing pressure differentials in packing phase are the major cause for core deflection during wax injection, which can be reduced by low packing pressures. The results show that more fixed core-pins can also reduce the thickness variation in the two sides of the thin-walled wax pattern. In this study, the core deflection during wax injection was successfully modeled, which will significantly help to understand the core deflection behavior in complex geometries during injection molding.