Optimization and selection of forming depth and pressure for box shaped Superplastic forming using grey based fuzzy logic

Abstract

Superplastic forming (SPF) is the first choice of designers for manufacturing parts with complexity as used in aircraft and automobile industries, where the strength to weight ratio is the main criterion. Superplastic forming of a sheet metal has been extensively used to produce the parts with greater complexities that are much stronger at the same time lighter than with other methods. Superplastic forming of sheets invariably results in thickness variation. Minimum thickness results at the portion where sheet comes in to contact with the die last. Pressure, forming depth and complexity of the part affect this thinning. The present investigation aims for simultaneous optimisation of forming depth and pressure of box shaped Superplastic forming using grey based fuzzy logic. In the present study Sn-Pb chosen; which is a model material for SPF to carryout experiments, the same results could be applicable for any other Superplastic material. Results revealed that depth at level1 (D1) and pressure at level 3 (P3) parameter settings minimize the time of forming, and maximize the thinning ratio, simultaneously.