Investigation of crucial geometric parameters and service life cycle of CBN grains on an in-service honing stone

Cubic boron nitride (CBN) composites frequently serve as tool materials in abrasive machining for surface finishing. The geometric features of individual CBN grains are crucial for both machining stability and the resulting surface quality of workpieces. While the grains, whether embedded in the matrix or exposed on the working surfaces, showcase seemingly ‘random’ geometric characteristics, they can typically be described through statistical analysis. In this study, three crucial three-dimensional geometric features of the CBN abrasive grains exposed on the working surface of a commercial CBN honing stone were characterized. These features include the protrusion height, inclination angle, and projection angle. In total, 116 abrasive grains identified within the processing zone were individually measured and inspected using a digital microscope and scanning electron microscope. The obtained results underwent statistical analysis and were subsequently compared. The results revealed that the abrasive grains exhibited an average protrusion height of 18.56 μm, an average inclination angle of 35.32°, and an average projection angle of 120.70°. Utilizing the measurement and inspection results, the abrasive grains were categorized into five distinct groups, each corresponding to a different phase in their service life cycle.