Experimental investigation of surface crack density and recast layer thickness of WEDMed Inconel 825

The present research attempts to analyze the surface topography of WEDMed Inconel 825 with respect to surface crack density (SCDi) and recast layer thickness (RCLt). Formation of cracks, recast layer and heat-affected zone are the major issues in determining the final performance of WEDM machined sample. In this study, WEDM characteristics viz. pulse on time (Ton), pulse off time (Toff), gap voltage (SV), peak current (IP), wire tension (WT) and wire feed (WF) are optimized for response SCDi and RCLt by response surface methodology. The outcome manifested that the topography of the machined surface becomes more rough at increased value of Ton, IP and SV. RSM emerged as a great tool in the development of a predicted model based on desirability approach and finding optimal parametric combination which results in reduced SCDi and RCLt. At optimum combination of process parameters i.e. 109 machine unit Ton, 36 machine unit Toff, 54 V SV, 120A IP, 9 machine unit WT and 7 m/min WF, the values obtained for SCDi and RCLt were 0.00160 μm/μm2 and 20.991μm respectively with an error of less than 5%.