New EDM polishing and texturing process with conductive polymer electrodes

To carry out these new EDM processes, an electrically conductive polymer electrode made of styrene-carbonaceous composite was investigated by design of experiments to minimize its electrical resistivity (0.08 Ω cm) and to maximize its thermal conductivity and formability. A compression molding module was also designed to perform efficiently multiple compression molding cycles of a same electrode. Since water is used as dielectric in the projected EDM processes, a preliminary evaluation of water as a dielectric medium, in conjunction with graphite EDM electrode, was performed. Finally, an experimental simulation of the “replica” method is presented, whereas a P20 tool steel workpiece with a macro-level 0.35 mm Peek-Valley milled surface roughness is smoothed down to a 0.25 mm PV in a single EDM iteration step in deionised water.