Wear characterisation and tool performance of sintered carbide inserts during automatic machining of AISI 1045 steel

Abstract

This paper presents tool condition monitoring (TCM) of dry turning processes on automatic lathes, and describes the information generated by different measuring systems applied to the single point turning situation. The outputs measured were correlated with the state and wear rate of the cutting tools. Semi-finishing and rough-shaping tests have been carried out at different cutting speeds. Uncoated sintered carbide inserts have been used in both processes, while TiC–TiN coated inserts have only been used in the semi-finishing processes. The behaviours of the utilised power, the tool-holder shank vibrations and the surface roughness vs. pass number were studied. The main criteria used for the wear assessment, were the roughness checks on work pieces in the semi-finishing processes, the electrical input by the lathe motor together with the vibrations level in the rough-shaping processes. The life of the tool inserts was assessed for each test, and Taylor's equation was determined for the three types of inserts used. The parameters investigated show that the results are directly influenced by degree of the tool wear and also give indications when the tool insert has reached the end of its life. Coated inserts permit approximately 50% longer machining time, a higher wear mark width and a reduced applied power consumption, compared with uncoated inserts. The end of tool life in the semi-finishing processes, when compared to the rough-shaping processes, refers to the higher power range used in the latter. The established relationships can be used in the evaluation of a tool insert's life and subsequently give rise to clear indications of the opportunity for higher productivity.