Topographic analysis of the crater wear on TiN, Ti(C,N) and (Ti,Al)N coated carbide tools

One of the criteria employed for analyzing cutting tool life used for cemented carbide tools is the depth of the crater (KT) located on the rake face, given as a function of the feed rate. This approach is thus considered a bi-dimensional measurement and it does not take into account the three-dimensional nature of this type of wear. In this work a 3-D surface topography measurement technique using a stylus-based profilometric data acquisition system, was employed for characterizing the evolution of the crater wear volume in coated hard metal tools. These cutting tools were used for turning quenched and tempered AISI 4340 steel on a lathe. Ti-N, Ti(C,N) and (Ti,Al)N films, deposited through the PAPVD process onto cemented carbide inserts were used as cutting tools. Evaluations of the wear volume using this 3-D topography technique were carried out for pre-established cutting times up to 22 min. Statistical analysis using a piecewise linear regression determined the existence of different crater wear regimes for each coated tool studied. These results bring a new approach and confirm the importance of the coating to the crater wear resistance, even if the coating has already been delaminated on the rake face.