The Effect of Material Microstructures on Tool Edge Preparation of PCBN Cutting Tools

PCBN tools are widely used in the machining of ferrous metals. Tool edge preparation is a crucial procedure in the tool preparation process that directly affects tool performance. In this paper, tool chamfer grinding and edge blunting were conducted on the PCBN tool to investigate the effect of material microstructures. In tool chamfer grinding, the PCBN tool with larger particles exhibits a larger chamfer width error and roughness than that of smaller particles, and the PCBN tool with higher Al content exhibits a larger chamfer width error and roughness than that with lower Al content. The optimal tool chamfer grinding speed is 24 m/s for the PCBN tool with larger particles, and 27 m/s for smaller particles. The optimal feed rate is 70 mm/min for both PCBN materials. In edge blunting, PCBN tools with larger particles or lower Al content are more difficult to passivate, and the optimal blunting time is about 30 s for an edge radius of 30 μm. The PCBN tools were prepared using the obtained machining parameters and used in the turning of brake pads. It is found that the PCBN tool with smaller particles exhibits longer life than that of larger particles. Although it exhibits the same wear characteristics, the tool life of the PCBN tool with lower Al content is longer than that of the tool with higher Al content.