A PRACTICAL APPROACH TO ELIMINATE DEFECTS IN GRAVITY DIE CAST AL-ALLOY CASTING USING SIMULATION SOFTWARE

Abstract

This paper deals with elimination of defects in aluminium alloy castings produced by gravity die casting process. The main intention of work is to investigate the defects and improve quality of a gravity die cast component using Computer Aided Casting Simulation Software. In this study an industrial gravity casting die is used which was producing defective components. The die and components produced by the die are studied to eliminate the defects using virtual simulations. The defects in the components are identified to be solidification shrinkage, cracks, unfilled riser and incomplete mould cavity. The reasons for the defects are analyzed as either improper selection of process parameters, or improper design of gating and risering system. SOLIDCast simulation software is used for simulating the solidification process of casting and visualizing outputs showing possible problematic areas or defects which may occur in the cast product. The work is carried out in two stages. In first stage, few test castings are produced by modifying the process parameters (pouring temperature, pouring time, pre heat and alloy type) and results are compared with simulation results produced using same parameters. The pouring and simulation results are observed to be in good accordance with each other. In second stage, number of virtual iterations of casting is performed by changing riser dimensions. It was found from the simulation results that riser with 35mm diameter is required to produce casting with zero defects. The die is modified accordingly with the simulation results and metal is poured. The castings produced are observed to be sound and contain no defects; and also it is verified that solidification simulation helps in locating the defects, eliminating them and ultimately improving the quality of castings without any shop-floor trails.