Self-sharpening ability of monolayer brazed polycrystalline CBN grinding wheel during high-speed grinding

Abstract

Polycrystalline CBN (PCBN) grinding wheel has self-sharpening ability, which is beneficial in maintaining its cutting ability, due to its unique structure. However, only few quantitative methods to evaluate the self-sharpening ability of PCBN are available. In this research, wear experiments of PCBN grinding wheel were carried out. The wear phenomena were discussed on the basis of SEM images and grain protrusion height. The self-sharpening ability of the grinding wheel was evaluated using fractal dimension. The grinding performance was discussed. Grinding experiments of monocrystalline CBN (MCBN) grinding wheel were conducted for comparison. Results showed that the main wear modes of PCBN grinding wheel were intergranular fractures and attrition wear of abrasive grains, whereas that of MCBN grinding wheel was transgranular fracture of grain. The fractal dimensions of PCBN grinding wheel nearly remained constant, whereas those of MCBN grinding wheel decreased continuously in the initial and steady wear stages. Lower standard deviation of grain protrusion height was obtained using PCBN grinding wheel than using MCBN grinding wheel during the steady wear stage. The active grain ratio of PCBN grinding wheel was 1.84 times larger and its grinding force was 18.6% lower than those of MCBN grinding wheel. An enhanced workpiece surface was obtained using PCBN grinding wheel.