Using Divided Pulses to Avoid Open Circuits in EDM

Constantin Diaconescu, PhD in Industrial Engineering was a professor at "Lucian Blaga" University of Sibiu - Romania, from 1979 to 2016. Currently retired, he is an associated professor at the same university. His main areas of interest are Pulse circuits, Digital electronics and VHDL design.

Electrical Discharge Machining (EDM) is a well-known machining technique since more then sixty years. Its principle is to use the eroding effect on metals of successive electric spark discharges created by the breakdown of a dielectric liquid. Many researchers indicate a ratio of open circuit pulses from 10% to 35% during the EDM process.Therefor, reducing the frequency of these unproductive pulses could increase significantly the machining performance. A prognosis of open circuit pulses being impossible to do, a solution is proposed to transform an open circuit pulse into a productive one. The basic idea of this solution is to increase the probability to obtain a breakdown of the dielectric liquid. The proposed technique consists in dividing the voltage pulse in a large number of elementary pulses, realising by that an enhancement of the thermal phenomena in the dielectric liquid, favouring the breakdown. To apply this solution, the architecture of a pulse generator, able to detect in real time an open circuit pulse and to apply in succession a divided pulse was conceived. This book is of interest for all engineers involved in improving the EDM techique.