Present study analyses the current process and suggests improvements based on computer simulation and testing. Simulating ductile iron castings using simulating tool can help to understand the solidification behaviour and determine the effect of graphite expansion on porosity. Optimal gating design can then be determined to help take advantage of this expansion effect in ductile iron castings and predict the properties for casting solidification, mould filling, mould design etc. in order to reduce the defects and finally the rejection.