Tool wear rate of the PCBN, mixed ceramic, and coated cemented carbide in the hard turning of the AISI 52100 steel

The hard turning process is generally performed by PCBN or mixed ceramics tools, which have the mechanical properties that withstand the tribological conditions of the process imposed by the hardened machined material. Coated cemented carbides are also an option for hard machining processes, although relying on the coating deterioration. This paper aims to evaluate the tool wear rate in function of the cutting speed in the hard turning of the steel AISI 52100 with a hardness of 50 HRC for three different types of cutting tool materials: coated cemented carbide, mixed ceramic, and PCBN. The methodology applied to assess the tool wear is based on three-dimensional parameters (volumetric) obtained from a focus variation microscope (FVM). The tool wear rate (WR_RM) is calculated based on ordinary least squares (OLS) adopting five values of W_RM in five machining time intervals. The face turning experiments were performed at four cutting speeds: v_c = 120, 150, 187.5, and 234 m/min. At v_c = 120 m/min, the PCBN presented the lowest tool wear rate (182 μm³/s); at v_c = 150 m/min, the coated cemented carbide (tool wear rate on the coating) had the best performance (417 μm³/s). The mixed ceramic tool presented a better performance at the higher cutting speeds of v_c = 187.5 and 234 m/min, 1206 and 1878 μm³/s, respectively. The methodology applied was reliable to understand and discuss the performance of the machining process through the tool wear rate (WR_RM), which is based on the volume of removed material from the tool (W_RM). The three-dimensional tool wear parameters can also be applied to machining process optimization, cutting tool wear model creation, benchmarking, and development of new cutting tool materials and grades. Furthermore, the methodology can be considered more agile and precise when compared to the current industrial methodology of tool performance evaluation. Thus, this innovative methodology promotes important information for cutting tool manufacturers and for its customers such as automotive and aeronautic industry.