Patent ID: 8921729

Claim:
A wire electrical discharge machine for machining a workpiece by moving a wire electrode relatively to the workpiece and by electrical discharge generated, from a power source unit for machining, between the wire electrode and the workpiece, the wire electrical discharge machine comprising: a numerical controller configured to set a wire electrode inclination starting position located anterior to a step portion; determine whether or not the wire electrode passes the wire electrode inclination starting position; carry out control of inclining the wire electrode when the numerical controller determined that the wire electrode has passed the wire electrode inclination starting position, wherein said inclining is within the machining plane with respect to a side where the machining plane, formed by relative movement of the wire electrode with respect to the workpiece, crosses the surface of the step portion of the workpiece; detect a change of a plate thickness in the step portion of the workpiece based on energy supplied from the power source unit for machining; determine that the wire electrode has passed a position of the step portion when the detected change of the plate thickness exceeds a preset value; and finish the control of inclining the wire electrode when the numerical controller determines that the wire electrode has passed the position of the step portion.