Tool Performance Assessment based on Three-Dimensional Tool Wear Rate

Abstract

Determining the tool wear rate is one of the key factors in the models to predict the tool performance. The challenge of the tool wear rate based on the flank or crater wear is the balance of the tool wear mechanisms and its impact on the tool wear pattern. This research aims to contribute to the tool wear fields showing a method to assess the tool wear rate based on the volume of removed material from the tool (wear parameter WRM), which has the advantage of encompassing the effect of wear phenomena on the whole cutting edge in one output value. The methodology applied consist of the measurement of the WRM parameter (performed by a Focus Variation Microscope) in pre-defined machining times. In the sequence, the WRM values are submitted to two filters: (a) progressivity and (b) stability criterion. The first is related to the progressivity of tool wear over the time, and the latter defines the maximum dispersion of rates within measured WRM values. The tool wear rate (WRRM) is calculated based on Ordinary Least Squares (OLS). The validation experiments were carried out with PCBN tools during hard turning AISI 52100 steel with 60 HRC in 120, 150 and 187.5 m/min cutting speeds. For 120 m/min, the tool wear rate was 608 μm³/s; for 150 m/min it was 1427 μm³/s (135% higher); and for 187.5 m/min it was 2950 m³/s (107% higher than the previous). It was found that the criteria for validating WRM data prevent calculating unrealistic tool wear rates. The method showed itself to be reliable and can inspire new approaches for cutting optimization with two major combined advantages: it is possible to apply the real tool wear values from the specific process studied, and short machining tests are necessary to acquire reliable tool wear values (WRM).