REPLACEMENT DETERMINATION DEVICE FOR ELECTRICAL DISCHARGE MACHINING ELECTRODE AND REPLACEMENT DETERMINATION METHOD

In order to solve the problem of being unable to precisely determine whether or not electrode replacement is required and the problem of the wear ratio of the electrode being set high for safety reasons and the electrode being replaced while still being usable, this replacement determination method determines whether or not replacement of an electrode (10) that sequentially electrical-discharge machines a plurality of throughholes (22) in a workpiece (20) is required. The replacement determination method: detects the remaining length (La) of the electrode (10); detects the electrical discharge commencement position, being the position of the electrode (10) when electrical discharge starts; detects the throughole position, being the position of the electrode (10) when the workpiece is pierced; sets the required length (Lb) for the electrode (10) as required for machining the next throughhole (22), on the basis of the difference (E) between the detected electrical discharge commencement position and the detected throughole position; compares the detected remaining length (La) and the set required length (Lb); and determines whether or not electrode replacement is required.