Real-time tool wear compensation in milling EDM

Accurate machining by milling EDM (i.e. CNC contouring EDM with a rotating cylindrical or tubular electrode) necessitates compensation of the tool electrode wear. Existing anticipated wear compensation is based on off-line tool wear simulation prior to machining. This can be combined with corrections based on periodical measurements of tool length during machining. Anticipated wear compensation involves an important restriction: an exact model of the blank geometry must be available in order to perform the tool wear simulation. This paper presents a new method of wear compensation. On-line estimation of tool wear is used for combining anticipated compensation with real-time compensation. This extends the scope of milling EDM to the machining of blanks of which the exact shape is not known in advance.