Preferentially oriented diamond micro-arrays: A laser patterning technique and preliminary evaluation of their cutting forces and wear characteristics

The conventional manufacturing methods of superabrasive grinding wheels generally result in random crystallographic orientations of the abrasive grits with their inherent positioning/spacing inconsistencies on the wheel's working surface. To strategically address these variances, the paper reports on a novel concept of robust generation of preferentially orientated and feature-controlled diamond micro-arrays. Firstly, an Nd:YAG Q-switched pulsed laser was used to accurately produce innovative patterns of micro-crystallite abrasive features in thick-film chemical vapour deposition (CVD) diamond where the size, spacing and orientation of the crystallites can be accurately controlled using carefully selected laser path and operating parameters. Geometrical characterisation of diamond micro-arrays have then been evaluated to enable reproducibility of the laser patterning technique as well as to have a robust basis for comparison of the wear evolution of the crystallites when tested in cutting conditions. Secondly, the performance of both polycrystalline and preferentially orientated ({1 0 0} and {1 1 0} faces) monocrystalline CVD diamond micro-arrays were evaluated in simulated surface grinding trials against a Ti-6Al-4V alloy workpiece where levels/mechanisms of wear of the crystallites as well as the main cutting forces have been analysed. It was found that the diamond micro-arrays of {1 0 0} orientation in the 〈1 1 0〉 direction had a higher wear than the diamond arrays of {1 1 0} orientation in the 〈1 0 0〉 direction, while both array types resulted in similar levels of cutting forces and workpiece surface roughness. However, the use of monocrystalline CVD diamond micro-arrays yielded considerable lower level cutting forces and wear of the crystallites when compared with the values obtained with micro-arrays made of polycrystalline diamond. Although this novel idea of exploiting these diamond micro-crystallites/arrays as customised cutting tools is at a preliminary testing stage, the paper concludes by giving directions in developing highly engineered (micro) tooling solutions for niche applications.