Optimization of process parameters during laser beam cutting of Ni-based superalloy thin sheet along curved profile using grey-fuzzy methodology

Abstract

Nickel-based superalloys are widely used in the aircraft and nuclear reactor industries due to their high strength-to-weight ratio and corrosion resistance properties at elevated temperatures. Typical applications of these superalloys demand technologically advanced cutting processes to create intricate shapes in macro- and microfeature sizes with exceptional good quality. These objectives can be obtained using laser beam cutting process. In this paper, multiple laser cut quality characteristics (i.e. top kerf deviation, bottom kerf deviation and kerf taper) are optimized simultaneously using grey relational analysis coupled with fuzzy logic during pulsed Nd-YAG laser cutting of thin Ni-based superalloy sheet. These laser cut characteristics are the functions of four laser cutting parameters, namely: lamp current, pulse width, pulse frequency and cutting speed where lamp current is considered as a new cutting parameter. The different values of lamp current are utilized to find the different levels of pumping energy which is further utilized to generate the laser energy. Further, laser cut results have been obtained by performing the experiments using Box–Behnken design (BBD). The results have been analysed using grey-fuzzy method to predict the optimum level of cutting parameters. The application of grey-fuzzy is capable to reduce the top kerf deviation, bottom kerf deviation and kerf taper in laser cut kerf by 47.69, 25.96 and 7.59%, respectively.