Comparative analysis of indirect, direct and hybrid cryogenic machining of Nimonic C-263 superalloy

Nickel based superalloys finds extensive usage in manufacturing of intricate part shapes in gas turbine, aircraft, submarine, and chemical industries owing their excellent mechanical property and heat resistant abilities. However, machining of such difficult-to-machine alloys up to the desired accuracy and preciseness is a complex task owing to a rapid tool wear and failure. In view of this, present work proposes an experimental investigation and optimization of process parameters of the cryogenic assisted turning process during machining of Nimonic C-263 superalloy with a multilayer CVD insert. Taguchi’s L-27 orthogonal array is used plan the experiments. Effects of input parameters viz. cutting speed (V), cutting feed (F), depth of cut (D) are studied on responses viz. surface roughness (SR), nose wear (NW) and cutting forces (CF) under indirect, direct and hybrid cryogenic (indirect+direct) machining environment. A scanning electron microscope (SEM) analysis is carried out to explore the post- machining outcomes on the performance measures. The multiple responses are converted in to single response and ranked according to Taguchi based grey relational analysis (TGRA). Feed rate (F) is found to be the most influential parameter from the analysis of variance (ANOVA) of grey relational grade (GRG). Further, the means of GRG for each level of process parameters are used to improve the optimal process parameters. Finally, a confirmative experiment is performed on the optimum machining conditions to validate the optimization study results. It is seen that the value of GRG is improved by 9.34% when compared to the previous best result. The proposed work can be beneficial to choose ideal process conditions to enhance the performance of turning operation.