Exploring the contribution of unconventional parameters on spark gap formation and its minimization during WEDM of layered composite

Abstract

Cladded materials are heterogenous in nature and considered as difficult-to-cut especially via conventional machining operations. Gas and/or plasma cutting are common in practice to cut clad materials. However, these processes induce deeper heat-affected zones and provide very rough surface integrity. Wire electric discharge machining (WEDM) is a capable alternate yielding better cut quality. Formation of a significant spark gap between the cut surfaces is the iconic problem of WEDM which is addressed in this study. WEDM has been performed on stainless-clad steel with a focus on identifying the significant parameters affecting the amount of spark gap and its minimization in the final cut. Eight input control factors, namely workpiece orientation, thickness of individual layer, servo voltage, pulse on-time, wire diameter, wire feed, and pressure ratio, have been employed to investigate their effects on spark gap development. Experimentation has been performed according to L18 orthogonal array followed by comprehensive statistical analyses. ANOVA shows that wire diameter and pressure ratio are the two main influential parameters for spark gap having percentage contribution of 71% and 16%, respectively. Optimal settings of control variables are also achieved through S/N ratio analysis. Improvement of 23.4% towards spark gap reduction is realized.