Precision hard turning provides an alternative to grinding in some finishing applications. Rapid tool wear, however, remains a bottleneck to the process being economically viable. This experimental study reports microstructural effects on cubic boron nitride (CBN) tool wear in finish hard turning. Results indicate that; 1) carbide sizes of the workpiece have significant effects on tool wear; 2) wear resistance monotonically increases with decreasing CBN grain size; and 3) in finish turning with low CBN content tools, the governing wear mechanism is fine scale attrition by microfracture and fatigue. A powder metallurgy M50 bar hard turned using an ultrafine CBN grain tool shows flank wear less than 45 um VBmax after 6.2 km cutting distance; wear rate equals to 3.1 ?m/km. Surface finish is better than 80 nm Ra.
Journal of Manufacturing Science and Engineering-Transactions of the ASME