Wear of WC inserts textured by shot peening and electrical discharge machining

In this paper, the wear and cutting performance of uncoated cemented tungsten carbide (WC) inserts textured by shot peening (SP) and electrical discharge machining (EDM) was compared to examine the hypothesis that texturing processes involving surface re-melting are inferior to processes based on surface plastic deformation. Lubricated orthogonal tube turning experiments demonstrated that the WC inserts with irregular rake face surface texture exhibit either longer or shorter tool lives than untreated inserts depending on the combination of surface roughness and residual stress. Higher roughness and compressive residual stress produced by SP led to increase in wear resistance and tool life by about 30% through reduction of the tool-chip contact area and the apparent tool-chip friction. Tensile surface residual stresses generated by EDM resulted in chipping of the tool and, hence, shorter tool life by more than 80% even when cutting forces were lowered. Moving the treated area away from the cutting edge neutralized the effect of texture on tool life. Based on the test results, surface modification of WC inserts through SP yielded better tool life performance than surface modification through EDM.