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 obse rvation and their study, by techniques usual in a plasma or material scienc e, have been undertaken. Following results have been obtained: measured pla sma channel temperatures reaches values between 8000K and 10000K; craters o bserved on an electrode melting zone show important surface carbon concentr ation enrichment on about 20 mu m depth; mean diameter of the erosion crate r on the cathode increases with time of the current impulse; for certain ap plied conditions, superposition of two current impulses, increased efficien cy of our EDM device. Particularly, in the case of the cemented carbide, th e improvement of erosion reached few hundred percents.