PROCESS VARIABLE OPTIMIZATION OF CASTINGS PRODUCED BY INVESTMENT CASTING PROCESS

Abstract

The ultimate aim of a foundry engineer is to produce defect free and dimensionally accurate castings with very good surface finish. The investment casting process is an ideal process for achieving desired dimensional accuracy, as no rapping allowing has to be given, thus eliminating machining to a great extent The present investigation is conducted to study the effect of process variables on the quality of Al - 7% Si alloy investment castings. Three variables mould material, pouring temperature, mould temperature have been varied at three levels keeping wax composition constant and Taguchi's experimental design technique have been used to plan the experiments. The characteristics for comparing the effect of variables were dimensional accuracy, surface finish, hardness and tensile strength. The experiments were conducted in accordance with L9 orthogonal array and it was found that best dimensional accuracy was obtained with level 3 of pouring temperature, level 1 of mould temperature and level 1 of mould material. Best surface finish was obtained with level 1 of pouring temperature, level 2 of mould temperature and level I of mould material. I larduess value was lound to he maximum for level I of pouring temperature, level I of mould temperature and level 3 of' mould material. Also tensile strength was Ibtind to he maximum for level 1 of pouring temperature, level 1 of mould temperature and level 3 of mould material.