In-process tool-failure detection of a coated grooved tool in turning

Abstract

With the increasing use of computer numerical control, there is a growing need to ensure a reliable system to optimise tool usage or tool wear. This paper presents a study on the fool failure of a coated grooved tool by monitoring the tool wear indirectly using the dynamic component of the tangential cutting force, Ft. Experiments conducted on AISI 4340 (ASSAB 705) and AISI 1148 (ASSAB 760) steels using a CNC lathe have revealed that there is a good correlation between the dynamic tangential cutting force and the flank wear of the tool. The natural frequency of the recorded dynamic force corresponds to the natural frequency of the tool. The results indicated a trend for Ft, which starts at a low value and fluctuates about this level during the normal wear stage. As VBmax increases to about 0.4 mm, the force increases rapidly in a non-linear fashion until the tool fails. Statistical analysis using a t-distribution test has showed that the dynamic tangential force gave a promising threshold value for the prediction for AISI 4340 and AISI 1148 steel. On-line tool-wear monitoring software was used to track the dynamic force signals to predict the possible onset of tool failure.