Evaluation of lapping characteristics by particle shape analysis

Lapping tests are carried out with an artificial poly-crystal diamond powder of sharp size-distribution and different shapes. The effect of particle shape on lapping characteristics is examined. The particle shape is described by expanding x and y coordinates of the particle outline into Fourier series independently. Then, the shape is represented by elongation ratio of the approximated ellipse calculated from the first-order Fourier coefficient and asymmetricity, polygonality and edge sharpness by slopes along the particle outline based on higher-order Fourier coefficients. Lapping characteristics are evaluated by the rate of decrease in work thickness, and by the surface roughness. As a result, a correlation equation was obtained where the lapping rate increases with increasing polygonality and edge sharpness and decreasing elongation and asymmetricity, and the surface roughness isn't significantly affected by the particle shape. Thus, it becomes possible to prepare diamond particles of different shapes by adjusting only the lapping rate.