The material removal mechanism in mechanical lapping of diamond cutting tools

In order to reveal the surface layer removal nature and explain the anisotropy of material removal rate in mechanical lapping single crystal diamond cutting tools, a brittle-ductile transition lapping mechanism is proposed. And then, the dynamic critical depths of cut for brittle-ductile transition in different directions on different planes can be calculated. The lapped surface layer of diamond cutting tool will be removed in plastic mode as long as the embedding depth of diamond grit into the lapped surface is less than the corresponding critical depth of cut. Lapping experiments on the named (110) plane and (100) plane are carried out and the lapped surfaces are measured with atomic force microscope (AFM). The results show that all the lapped surfaces of diamond cutting tools consist of plastic grooves in nanometric scale and the maximal groove depths have prominent anisotropy in different orientations and on different planes, which are consistent with the critical depths of cut well. Therefore, the material removal rate anisotropy of lapped surface layer can be analyzed by comparing the critical depths of cut on different crystallographic planes and in different orientations of the identical plane quantitatively.