Design and Manufacturing of Defect-Free PumpCasings: A Numerical and Experimental Approach

Abstract

Internal shrinkage defects often occur in sand-cast gray cast iron pump casings, particularly in areas with abrupt thickness variations where heat dissipation is limited. These defects form during the final stage of solidification when isolated liquid metal cannot be properly fed. In this study, the solidification behavior of an industrial pump casing is investigated through coupled thermal–flow simulation to analyze temperature gradients and feeding paths. The results show that delayed solidification at the flange–root junction leads to isolated liquid zones that develop into shrinkage cavities. By modifying the feeding layout, heat extraction and directional solidification toward the riser are improved. Experimental casting with the optimized design shows no visible shrinkage defects and achieves an average hardness of 42.3 HRA. These findings highlight the importance of maintaining solidification continuity to eliminate defects in gray cast iron pump casings [1].