Numerical and experimental study of the elimination of shrinkage in complex and small investment castings using water cooling process

Abstract

Shrinkage porosity, one of the most serious defects, is usually formed in castings. The traditional ways in solving these kinds of defects are adding feeding channels, risers, placing metallic chills, optimizing the gating system, and so on. Indeed, they are effective methods to solve shrinkage defects in large castings, but not to the complex and small castings. In this research, one small and complex investment casting was investigated for its inner shrinkage defects. Since the defects are unsuitable to the traditional optimal ways. A novel method, dipping the preheated shell mold in water, was used to optimize the order of solidification. Both finite element method (FEM) analysis and experiment results show that the solidification sequence was optimized, and the shrinkage was eliminated. It shows that the water cooling process is an available approach to eliminate shrinkage defects in those complex, small, while with big length to width ratio investment castings.