Mold Design Optimization for Sand Casting of Complex Geometries Using Advance Simulation Tools

Abstract

Defects data and design optimization of gating system are a great challenge in casting. Most significant factors contributing to the volumetric changes and defects are pouring temperature, time, filling pattern, gating system, and casting geometry. The optimized design of gating system facilitates the smooth filling of the mold without air entrapment, material flow hindrance. Conventionally, the foundry method includes design calculations, best practices, and the tedious hit-and-trial method to get the optimum design of pattern/mold for defect-free casting. The design iterations and improvements directly affect the development cost and time, and one of the great challenges of the foundry method is to reduce this time and cost. The numerical simulation techniques embedded in casting simulation software are a powerful tool to overcome these challenges. It predicts the factors such as filling pressure, velocity, cooling rate, hot spots, and inside porosity. This article describes the design, simulation, experimental results, and design improvements for the complex geometries in the sand casting process. Impeller is selected as test case. The gating system was initially designed by using the text book mathematical relations and best practices recommendations. To study the predicted results of effected parameters, MAGMASOFT Software was used as a simulation tool. Three design modifications of mold design were studied. The effect of design including location and size of risers, gates on parameters such as filling pattern, pressure and velocity, cooling rate, solidification and defects such as air entrapment, hot spot, and porosity were studied. The predicted results were then compared with experimental data, and an excellent agreement between them was reported. The article highlighted the effectiveness of simulation to reach an optimal design of mold by passing the costly hit-and-trial conventional practice in the foundry industry and shows the effectiveness of simulations in time compression of casting pattern/development.

Keywords:

• Air entrapment
• Cast alloy
• Hot spot
• Impeller casting
• Numerical simulation
• Porosity
• Process modification