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Abstract

Commonly, on Die Sinking Electrical Discharge Machining (DS EDM), a special generator enables current pulses in sinusoidal or triangular shapes, only in a single polarity. The duration and the amplitude are adapted to the machining sequence, allowing the achievement of different surface finishing. By using a new configuration, it is shown that if one applies pulses of current in both polarities, related together but with a certain ratio between the positive and the negative peaks current, machining results could be improved. The purpose of this new generator is the ability to control with great flexibility the generation of these pulses, in terms of durations, amplitudes and sequence. These parameters can be independently selected for the positive and negative polarity and modified during the machining. One can also choose a special predefined or settable sequence of pulses. The generator includes also the double polarity ignition and the high-speed gap breakdown detection. An embedded programmable circuit (FPGA) provides a high-speed control of the sequence. Machining tests have been performed in order to explore and quantify different sequences of pulses in terms of machining results and performances achieved, compared against the current situation.

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