Selective surface enhancement by Milling EDM with ti and WC-Co electrodes

The quality of machined surfaces has always been a main concern and research topic in EDM. Investigations on surface alloying (selective surface enhancement) for sinking EDM showed that it is possible to improve the properties of the recast layer by using special electrode materials. The aim of the present research is to improve the hardness and wear resistance of a (iron and/or tool steel) workpiece surface by milling EDM. Milling EDM uses standard shaped tubular electrodes and has important advantages over classical die sinking EDM for selective surface enhancement using non-classical electrode materials. During EDM the electrode wears and some of these wear particles reach the top layer of the workpiece and form very hard alloys if a suitable electrode material is selected. The challenge is to create a recast layer with a good quality, sufficient thickness, limited roughness and enough alloyed material to increase its hardness and wear resistance. A substantial improvement in wear resistance for iron and tool steel was obtained using Ti electrodes. Dedicated Ti electrodes were made to increase the electrode wear. Milling EDM with WC-Co electrodes increases the hardness of the recast layer but not the wear resistance.