Wire electric discharge machining method of machining workpiece with different thickness

A wire electric discharge machining method of machining a workpiece into a required shape with a first cut and a second cut, each cut corresponding with different machining conditions and a wire path on which a wire electrode is moved relative to the workpiece being set for the cut, the method comprising the steps of:

• (a) detecting a position of the wire electrode relative to the workpiece;
• (b) detecting a change in thickness of the workpiece during the first cut;
• (c) storing the position of the wire electrode as a thickness change position when change in thickness of the workpiece from a first thickness to a second thickness is detected;
• (d) forming a zone around the thickness change position;
• (e) comparing the position of the wire electrode to the zone during the second cut;
• and
• (f) changing at least one machining condition during times when it is determined that the wire electrode is positioned in the zone.