Effect of laser texturing on the performance of ultra-hard single-point cutting tools

This paper investigates the cutting performance and anti-adhesive properties of textured single point polycrystalline diamond (PCD) cutting tools in machining Aluminium 6082 alloys. The micro/nano textures were first milled using a fibre laser (1064 nm wavelength) at different power intensities, feed speeds and pulse durations, and finally characterised using scanning electron microscopy, white light interferometry and energy dispersive X-ray spectroscopy. The effect of different textures on the cutting performance was investigated in turning tests under dry cutting conditions. The test was stopped at regular lengths of cut to allow analysis of height of adhesion through 3D white light interferometry. The data processing of the cutting forces and the microscopical characterisation of the tested cutting tools enabled the evaluation of the effects of texture design, friction coefficient and adhesive properties. The results indicated that feed force in tools with grooves perpendicular to the chip flow direction (CFD) was more stable (20-40N) than the benchmark (6-41N). Similarly, the thrust force for tools with grooves parallel to CFD and grooves perpendicular to CFD showed a homogeneous trend fluctuating between 60N to 75N as compared to the benchmark (ranging between 73N to 90N). For texture depth in the order of 260 nm and post process roughness in the order of tens of nanometers a reduction of average friction coefficient (0.28±0.14) was reported when using lasered inserts with grooves parallel to the chip flow direction compared to the benchmark tools (0.34±0.26) corroborated by reduced stiction of workpiece material on the rake face. In machining via textured tools with grooves perpendicular to CFD, the cutting forces were reduced by 23%, and the surface quality of the machined workpiece was improved by 11.8%, making this geometry the preferred choice for finishing applications. Using grooves parallel to CFD reduced the cutting forces by 11.76%, adhesion by 59.36% and friction coefficient by 14.28%, however it increased the surface roughness of the machined workpiece, making this geometry suitable for roughing operations. For the first time, laser manufacturing is proposed as a flexible technique to functionalise the geometrical and wear properties of PCD cutting tools to the specific applications (i.e. roughing, finishing) as opposed to the standard industrial approach to use microstructurally different PCDs (i.e. grain size and binder%) based on the type of operation.