Multi-objective analysis of ball burnishing process by Grey-Taguchi and Grey-Fuzzy methods

Abstract Rare earth based magnesium alloys exhibit superior performance than other alloys of magnesium. However, their application in automotive, aerospace and biomedical applications was constrained because of poor wear, corrosion and tribo-corrosion characteristics. The main aim of this project was to improve the surface integrity features such as surface roughness and hardness by ball burnishing technique and thereby, enhancing the wear performance. The multi-performance characteristics were optimized and predicted by using Grey-Taguchi and Grey-Fuzzy methods respectively. Also, the wear performance was evaluated at optimum multi-response condition. The best surface roughness of R a = 0.306 μm with an improvement of 67.48% and the best microhardness of 103.1 HV with an improvement of 37.10% has been obtained by grey analysis. Additionally, it was found that the burnishing force contributed for 35.02%, burnishing feed for 25.53%, burnishing speed for 20.93% and passes for 13.89% in achieving the best surface integrity of ball burnished Ze41A. The surface morphology images conclude that the surface at optimum burnishing condition was smoother, uniform and harder than that of initial milling condition. The tribology results at optimum burnishing condition reveal that wear rate reduced by 51.23%, CoF by 34.04% and interfacial temperature by 22.22% than that of initial milling condition. The results emphasize that ball burnishing technique outperforms as a surface modification treatment in improving the wear performance. The grey-fuzzy technique is found to be consistent, robust and accurate method in estimating the multi-responses of ball burnishing process.