Enhanced wear performance of laser machined tools in dry turning of hardened steels

Polycrystalline boron nitride cutting tools are currently used for precision machining of automotive components made of hardened steel due to their high wear resistance and long durability, however adhesion of workpiece to the cutting tool can reduce cutting tool lifetime. Laser surface engineering of polycrystalline boron nitride single point cutting tools using a nanosecond fibre laser is proposed to improve their wear properties and extend tool life in turning of continuous hardened steel components. The effect of different designs on the wear properties was investigated in turning tests under dry conditions and compared to benchmark cutting tools made of the same material. Condition monitoring of machining forces revealed a 20% reduction of cutting force and 30% reduction of feed force for tools with crosshatch design and grooves perpendicular to chip flow direction, when benchmarked to commercial cutting tools. The number of grooves in contact with the forming chip contributed to the creation of three distinguished interfacial secondary deformation areas. Texturing the chamfer proved to alter the dynamic of chip formation in the secondary deformation zone, while engineering the formation of laser induced solid lubricant h-BN improved the heat dissipation rate in the secondary and tertiary deformation areas. To the best of authors' knowledge, this paper reports for the first time the possibility of simultaneously engineer geometry and chemistry of PcBN cutting tools so to enhance their service life by up to 20%.