Effect of evaporative pattern casting process parameters on the surface roughness of Al–7% Si alloy castings

Evaporative pattern casting (EPC) process has drawn great attention from both academia and industry in recent years. The expandable polystyrene (EPS) pattern is a key feature of EPC process which is buried in unbonded sand and replaced by molten metal. This paper investigates the effect of process parameters like degree of vacuum, pouring temperature, grainfiness number, amplitude of vibration and time of vibration on the surface roughness of Al–7% Si alloy castings in EPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired surface roughness. The central composite rotatable design has been used to conduct the experiments. The analysis of results indicates that the surface roughness increases with increase in degree of vacuum, pouring temperature. Whereas, it has an inverse relationship with grainfiness number, amplitude of vibration and time of vibration.