Wire electric discharge machining device and method

A wire electric discharge machining device that starts machining of a workpiece by generating an electric discharge in a machining gap formed between the workpiece and a wire electrode threaded through a start hole in the workpiece, the wire electric discharge machining device comprising:

• a tension controller consisting of an input device, a memory device, and a processor, the tension controller outputting a command based on a detected value of tension of the wire electrode measured by a strain gauge and a gain, and controlling a rotational speed of a servomotor, which rotates a roller to give the tension of the wire electrode to be maintained at a set value;
• a short circuit detection circuit detecting a short circuit between the wire electrode and the workpiece, wherein the short circuit detection circuit is connected to a counter;
• and
• a short circuit termination equipment having at least one of a vibrator or a vertical motion device having a compressed air supply device, wherein the short circuit termination equipment reduces the tension of the wire electrode and vibrates the wire electrode to terminate the short circuit when the short circuit detection circuit has detected the short circuit,
• wherein the short circuit termination equipment reduces the set value of the tension to 10 to 50% when the short circuit detection circuit has detected the short circuit.