Abstract: Automatic monitoring system and method for providing an instantaneous tool status indication for a stock removal cutter when cutting workpieces in accordance with a given machining operation for which a substantially new stock removal cutter of the same type has a reference average tool wear coefficient R0. The system includes a torque monitor (7) for measuring a main drive cutting torque M during the cutting of an ith successive workpiece. Coupled to the torque monitor (7), is an instantaneous tool wear coefficient processor (13) for calculating a plurality of instantaneous tool wear coefficients r(j) during the cutting of the ith successive workpiece.

Abstract: A controller for optimization of metal-working on CNC-operated machine tools, includes a first unit for monitoring the torque of the main drive of the machine tool to establish the actual, instantaneous cutting torque, a second unit for setting the rated cutting torque in the teaching mode in dependence on the main-drive torque as monitored, a third unit for calculating the feed rate required to maintain the cutting torque at a constant level and controlling the feed drive, and a fourth unit responsive to the monitored main-drive torque and providing feed rate limiting signals to the third unit for protecting the tool against breakage.