Factors governing the onset of severe drag tool wear in rock cutting

Laboratory cutting tests have been performed in hard rock utilising an instrumented 50 tonne capacity rock planer. The experiment involved intermittent cutting of felsic gneiss up to a maximum of 20 m or until tool failure. Each cutting tool was fitted with a thermocouple in the tungsten carbide insert to monitor the insert tip temperature. The cutting forces and tool wear were also monitored. Cutting was conducted with and without high pressure water jet assistance (HPWJA). The results show that a dependence exists between the tool temperature and the tool normal force component. HPWJA enhances the tool life and acts as a heat sink during cutting. An elementary model is proposed to explain the findings and provide a theoretical basis for anticipating high tool wear. (C) 1997 Elsevier Science Ltd.