Patent ID: 7262381

Claim:
A controller for a wire electric discharge machine for performing machining of removing part of a workpiece by electric discharge generated between a wire electrode and the workpiece while moving the wire electrode relative to the workpiece, said controller comprising: machining rate determining means for determining a machining rate which is an amount of removed part of the workpiece in a predetermined time period; motion control means for controlling motion of the wire electrode relative to the workpiece in accordance with the determined machining rate such that a motion rate, which is an amount of motion of the wire electrode relative to the workpiece in the predetermined time period, decreases when the machining rate increases; switching means for switching a set value of the motion rate for a reference value of the machining rate from a first value to a second value smaller than the first value when the machining rate increases to be greater than a first threshold, and changing the set value of the motion rate back to the first value when the machining rate decreases to be lower than a second threshold.