Performance Indicators of Grinding Tools with Cubic Boron Nitride Grains with Combined Wear-Resistant Coatings

We investigated the effect of surface coatings on cubic boron nitride (cBN) grains regarding tool wear resistance and processing efficiency. At a low processing rate (50 mm³/min), the wear resistance enhancement factor was 1.66 for the B₂O₃ + CeO₂ coating. Conversely, at a higher processing rate (200 mm³/min), the wear resistance enhancement factor decreased to 1.13 for the B₂O₃ + B₄C coating. The study demonstrated that under these processing conditions, surface coating of cBN grains with a combination of oxide and carbide (B₂O₃ + SiC) is preferable. This preference is based on improved grinding wheel wear resistance and reduced surface roughness (R_a) of the machined surface. Furthermore, at increased grinding efficiency, any coating on cBN grain surfaces decreases the t50 parameter, thereby decreasing the holding capacity of the rough surface generated during grinding with such wheels.