Material Removal Characteristics and Polarity Effect in Micro EDM
To further investigate the material removal characteristics in micro electrical discharge machining(mi-cro EDM),a multi-physical field coupled simulation was conducted on the thermal conduction at the discharge point and the material removal process,and single pulse discharge experiment was carried out for validation.Based on the motion characteristics of electrons and ions within the discharge plasma channel,the polarity effect in micro EDM was analyzed.The results show that the edge protrusion of the discharge crater can be formed by introducing Marangoni convection module,and the simulated discharge crater morphology is consistent with the measured discharge crater morphology.The energy utilization rate of short pulse discharge is relatively high,and the energy utilization rate decreases gradually with the increase of discharge duration.By introducing the actual discharge conditions to conduct the model correction,the simulation accuracy of the discharge crater radius can be improved to less than 7％.The acceleration and velocity of electrons in the discharge channel are very high,the number of times that electrons bombard the surface of the positive electrode in the same time is more than 40 times that of positive ions bombarding the surface of the negative electrode.Therefore,the material removal rate at the anode is significantly higher than at the cathode,and micro EDM exhibits a pronounced polarity effect.
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