Chipping and crushing mechanisms in orthogonal rock cutting

The understanding of rock removal mechanisms, as one of the essential elements for advancing the cutting performance of polycrystalline diamond compact (PDC) cutters, is still incomplete. This paper is seeking to formulate a cutting theory to analytically explain how rock interacts with PDC cutters in a simple cutting configuration – linear cutting. In the proposed approach, a rock crushing zone is introduced at the rock-cutter interface beneath the cutter's rake face, namely the Tip Crushing Zone (TCZ), which, as a destruction kernel, is responsible for both the crushing and chipping phenomena occurring in the cutting process. The physical aspects of these two disparate chip formation mechanisms are discussed. Moreover, closed form expressions for the cutting and thrust forces are derived based on the equilibrium of moments and on the minimum chipping energy principle. To evaluate the force model, comprehensive linear rock cutting tests were conducted on a newly developed rock cutting facility. Both the chip formation phenomena and force responses are in good agreement with the newly proposed theory.