New interesting results on the electro-discharge machining

To have a better understanding of processes which play a role in erosion of electrodes caused by electro-discharge machining (EDM) plasmas, including the physical and chemical transformations in electrodes, it is important to know physical characteristics of the plasma and eroded materials. Its observation and their study, by techniques usual in a plasma or material science, have been undertaken. Following results have been obtained: measured plasma channel temperatures reaches values between 8000K and 10000K; craters observed on an electrode melting zone show important surface carbon concentration enrichment on about 20 mu m depth; mean diameter of the erosion crater on the cathode increases with time of the current impulse; for certain applied conditions, superposition of two current impulses, increased efficiency of our EDM device. Particularly, in the case of the cemented carbide, the improvement of erosion reached few hundred percents.