Temperature and stress influence on the tool wear mechanism of machining Zr-based bulk metallic glasses

Abstract

Bulk metallic glasses (BMGs) show excellent physical and chemical properties. However, during the machining of BMGs, the poor thermal conductivity led to severe tool wear. Among the various factors influencing the tool wear, cutting temperature and stress field played the most significant roles. In order to study the influence of cutting temperature and rake face stress field on tool wear behavior, the tool wear mechanisms of machining BMGs at different cutting speeds and corner radii were investigated in this study. The changes in wear morphology of the tool rake face and flank face were analyzed. The main wear mechanisms were adhesive wear and abrasive wear. Moreover, the cutting temperature was calculated to characterize the influence of cutting speed on tool wear behavior, and the influence of corner radius on tool wear behavior was also analyzed with considering the stress field on the rake face. With the increase in cutting speed, the cutting temperature increased from 777 K to 1216 K, with an increase of 56.5 %, leading to the thermal softening and hardness reduction of workpiece material. This resulted in enhanced adhesion on the rake face and diminished grooving on the flank face. As the corner radius increased, the maximum normal stress decreased from 1732 MPa to 986 MPa, a decrease of 43.07 %, which reduced the ploughing effect of hard particles on the tool surface and diminished the abrasive wear on the rake face. And it also reduced the adhesion tendency on the rake face, thereby reducing the adhesive wear.