Abstract
Modelling and optimization of manufacturing processes for better quality engineered parts has always been a requirement. Numerous statistical and soft computing techniques have been used for this purpose. This paper reports on modelling and computation of Wire-EDM process parameters for optimum productivity and surface quality when machining Ni55.8Ti shape memory alloys using a TOPSIS-Fuzzy-PSO integrated hybrid technique. Ni55.8Ti is an important biomaterial and its appropriate machining at optimum set of parameters is essential to achieve high process productivity and to simultaneously maintain high product quality. Productivity in terms of material removal rate ‘MRR’ and surface quality in the form of maximum roughness ‘Rt’ and recast layer thickness ‘RCL’ have been considered. Four wire-EDM parameters namely servo voltage ‘SV’, pulse-on time ‘Pon’, pulse-off time ‘Poff’, and wire feed rate ‘WF’ have been varied at four levels each to machine Ni55.8Ti alloy based on Taguchi L16 robust design of experiment technique and the aforementioned conflicting responses have been measured corresponding to each experiment. To establish the relationship between wire-EDM parameters and the responses, all the response characteristics were converted into a single response of TOPSIS-fuzzy performance index (TFPi). PSO coupled with TOPSIS and Fuzzy logic has been employed for computation of optimum wire-EDM parameters for the best values of all responses considered. Analysis of variance (ANOVA) of TOPSIS-fuzzy performance index (TFPi) exhibited the effectiveness of the integrated hybrid technique. The optimum values of wire-EDM parameters obtained by hybrid technique are SV-50V; Pon-1µs; Poff-17 µs; WF-4 m/min for MRR-0.049 g/min, Rt- 11.45 µm, and RCL- 22.10 µm. Validation experiments conducted to confirm the reproducibility of the response characteristics predicted by hybrid technique.