Surface fractal evolution of fracture behavior of polycrystalline cBN grains in high-speed grinding

Abstract

High-speed grinding experiments on nickel-based superalloy Inconel718 were carried out with single grain of polycrystalline cubic boron nitride (PcBN). Surface fractal evolution of fracture behavior of PcBN grains was discussed. The fracture reason of PcBN grains was studied from the viewpoint of grinding load based on finite element method (FEM). Results obtained show that micro fracture behavior is the predominant wear pattern of the PcBN grain cutting edges. Because the tested grains have different wear patterns, the statistical relationship is established between the fractal dimension of the grain cutting edges and the attritious wear flat percentage. The dynamic grinding force is the determining factor for the micro fracture behavior of the grain cutting edges in the particular region, where the grain firstly contacts the workpiece in the initial stage of the grinding process.