Design and experimental study of a multi-mode controllable RC pulse generator for micro-EDM

A multi-mode controllable RC pulse generator is developed with the state-of-art electronic technique. The circuit can work at both pulse-train and isopulse mode, and a 100ns open-circuit pulse on-time can be achieved. By drilling micro via and blind holes, the influences of capacitance and pulse parameters to the process are studied. For both pulse-train and isopulse mode, the existence of the capacitance will lead to a sharper rising edge, high density and less vibrating of the discharge current, which results in a more effective metal removal rate per pulse. With the pulse-train mode, when the capacitance is smaller than a certain value, with the increase of it, the machine time decreases and the side discharge gap between electrode and via hole is almost unchanged. The value of certain capacitance is 15000pF with the controllable RC circuit. And with the existence of the capacitance, the discharge can also remove metal during pulse-off time, and a high discharge frequency and machining speed can be achieved. With isopulse mode, the discharge energy is more consistent, and better surface roughness can be achieved.