Tool breakdown detecting system
A tool breakdown detecting system having at least one predicted standard pattern of change in the cutting resistance of a tool corresponding to a possible breakdown is prestored in a memory and compared with an actual change pattern of the cutting resistance of the tool monitored during working. When a coincidence is found between the prestored change pattern and the actual change pattern of the tool this indicates a breakdown of tool an alarm signal is generated. The alarm signal can activate a visual or audible alarm as well as regulate the further movement of the tool.