Impact Analysis of Electrode Material on Electrical Discharge Grinding Polycrystalline Diamond Cutting Tools

Abstract

The electrode material plays a very important role in the electrical discharge grinding (EDG), affects the electrical discharge machining efficiency and machining surface quality. Experiment testing and materials analysis as the primary method, affected layer thickness and workpiece surface roughness value as evaluation indexes. Polycrystalline diamond cutting tool samples were electrical discharge machined using copper electrodes and graphite electrodes respectively. After machining, the polycrystalline diamond cutting tool samples’ surfaces was analyzed by X-ray diffraction, Surfaces appearances were observed under the scanning electron microscope, and the surface roughness values were measured by the roughness measuring instrument. Polycrystalline diamond samples’ surface effect layer thickness values and surface roughness values, affected layer distribution structure was statically analyzed in typical EDG process conditions with different electrode materials. Test results demonstrate that the affected layer is inevitably presented on a polycrystalline diamond surface after electrical discharge grinding polycrystalline diamond. The principal cause of the affected layer is the diamond graphitization and the decomposition of binders. In the same EDG process parameters, the processing efficiency of the graphite electrode is clearly higher than that of the copper electrode; but the tool edge roughness value and affect layer thickness of the graphite electrode machining is greater than those of the copper electrode machining. This research provides an essential experimental basis for designing technics of precision and highly efficient electrical discharge grinding polycrystalline diamond cutting tools.