A basic analysis of pulse trains in electro-discharge machining

Abstract The paper analyses the time-averaged effects of ignition delay and inactive pulses (short circuit and open circuit), assuming rectangular pulses in electro-discharge machining. Consideration is given to both the normal voltage-pulse timed, and current-pulse timed (isopulse) types of generator system. Relationships derived demonstrate that both ignition delay and the incidence of inactive pulses affect the erosion performance of the former type of generator, whereas the current-pulse timed generator is susceptible only to the effects of ignition delay and short-circuit conditions, in these terms. Nevertheless a basis for analysis of the comparative performance of these types of generator is discussed. Actual (non-rectangular) pulses are considered, and various methods for derivation of the “equivalent rectangular pulse” are examined, including the principles of conservation of charge, conservation of energy, and the “minimum departure area” criterion.