Surface integrity of tool steels multi-cut by wire electrical discharge machining

Electrical discharge machining removes electrically conductive material by means of rapid and repetitive spark discharges resulting from local explosion of a dielectric liquid. The electrical discharge machining has been widely used for cutting fine blanking tools which are made of especially hard tool steels. Whereas, its thermal nature causes great concerns regarding surface integrity, which matters a lot to tool life. In the present study, the evolution of surface integrity of the S390 and SKD11 with multi-cutting is comprehensively compared. The result shows that the surface roughness, white layer thickness and surface residual stress decrease with the increase of cutting pass. Compared to the finish trim cut surface of S390 sample, more pinholes and slightly larger craters were produced and the micro cracks could be found on the finish trim cut surface of SKD11 sample. (C) 2014 Published by Elsevier Ltd.