Bio-inspired self-sharpening cutting tool surface for finish hard turning of steel

This research presents the structural analysis and machining results of a 3-D nanostructured coating designed for finish turning of ferrous alloys. The coating design, inspired from sea urchin and shark teeth architectures, delivers serrated cutting edges and self-sharpening. The coating is realized using cubic boron nitride particles (<2 μm in size) in soft titanium nitride matrix to produce superior tool life and consistent surface finish (<1.6 μm), on-par or better than polished PCBN inserts, during finish hard-turning of 4340 alloy steel. This research also discusses mechanism based on coating materials and morphology for reducing surface contact and sliding friction at the tool–workpiece interface.