A method for electrical discharge machining (EDM) a workpiece by means of a train of machining pulses. During the machining time the machining pulses are applied to the working gap between workpiece and electrode. An open voltage is first applied, and it is increased to a second open voltage level if a discharge does not occur within a waiting time do, and further increased to a third open voltage level if a discharge does not occur within a second waiting time d.sub.1. The discharge electrical parameters can be adjusted according to the duration of d0 and d1.

A method for electrical discharge machining (EDM) a workpiece by means of a train of machining pulses. During the machining time the machining pulses are applied to the working gap between workpiece and electrode. An open voltage is first applied, and it is increased to a second open voltage level if a discharge does not occur within a waiting time do, and further increased to a third open voltage level if a discharge does not occur within a second waiting time d.sub.1. The discharge electrical parameters can be adjusted according to the duration of d0 and d1.