Optimization of tensile properties of evaporative pattern casting process through Taguchiʹs method

Evaporative pattern casting (EPC) process allows the production of complex parts and reduces machining of the part. To make a casting by EPC process, an expandable polystyrene pattern of the final part is made. In EPC process, all the limitations imposed by the binders and additives are absent as it is a binderless process. In this paper an attempt has been made to achieve a set of values of EPC process parameters that may yield optimum tensile properties to the Al–7% Si alloy castings. The effect of selected process parameters on the tensile properties of Al–7% Si alloy casting and subsequent optimal settings of the parameters have been obtained using Taguchi parametric design approach. The results indicate that the grain fineness number and the pouring temperature are the significant parameters in deciding the tensile strength and percent elongation after fracture of Al–7% Si alloy castings. Time of vibration and degree of vacuum are insignificant parameters. The predicted optimal value of tensile strength and percent elongation after fracture of Al–7% Si alloy castings produced by EPC process are 141.17 N/mm2 and 2.713%, respectively, at 22 kg/m3 density of expandable polystyrene pattern.