Multi-response optimization of electrochemical micromachining on masked SS304

Abstract

This paper investigates on electrochemical micromachining of woven fabric masked stainless steel SS304 using 0.5 mm copper tool electrode with sodium nitrate (NaNO3) Electrolyte. Investigation is carried out to express the performance measures of micro hole such as metal removal rate (MRR), taper angle (TA) and surface roughness (SR). The experimental plan is based on taguchi L16 orthogonal array. Various input process parameters such as voltage, duty ratio, rotational speed, feed rate of tool and electrolyte concentration are varied at four levels. Significant contributions by input process parameters for each output responses such as metal removal rate, taper angle and surface roughness are analysed using contour plots. It is evident that significant contribution to metal removal rate mainly depends on rotational Speed and feed rate of tool. Similarly, duty ratio and feed rate of tool are the significant contributors for both taper angle and surface roughness. Multi response optimization are done for the three output responses using VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method to identify the significant process parameter. Performance score of VIKOR and TOPSIS proved that rotational speed of tool, feed rate and duty ratio are important parameters contributing significantly for precision of microfeatures. Both the multi response optimisation methods mutually concluded the best performance is achieved at voltage 21 V, duty ratio 80%, rotational speed of tool 600 rpm, feed rate of tool 0.8 μm s−1 and electrolyte concentration 0.2 M. The confirmation test showed an improvement of performance grade by approximately 0.245.