Response optimisation in wire electrical discharge machining of AISI H11 tool steel using Taguchi - GRA approach

摘要

Wire electrical discharge machining (WEDM), is the most commonly used thermoelectric method to machine electrically conductive materials because of its ability to machine any complex and intricate shapes with increased precision and dimensional accuracy. In this study, the fatigue samples are prepared through WEDM process according to Taguchi's L9 orthogonal array (OA) of experiments by varying the pulse time (T_(ON)/T_(OFF)) and wire speed, each at three levels. The parametric effect on fatigue life, surface roughness (SR), material removal rate (MRR), recast layer depth and microstructure is studied. The recast layer and microstructure of the machined samples were analysed using scanning electron microscopy (SEM). From the results, the fatigue life of the component decreases (53.86%) as the T_(ON) time increases (108 μs to 112 μs). This reduces the surface quality by 21.37% and increases the depth of recast layer. Simultaneously, an improvement of 14.31% in MRR was obtained by increasing the T_(ON) from 108 μs to 112 μs and wire speed from 1 m/min to 3 m/min. The optimal level of the factors for better responses was found by Taguchi response graph and variance analysis. Grey relational analysis (GRA) was done for overall process optimisation.