An approximate upper bound approach for the single-grit rotating scratch with a conical tool on pure metal

An upper bound model has been proposed for the single-grit rotating scratch with a conical tool on a rigid perfectly-plastic material. The model was validated experimentally with a newly-developed technique to make scratches on annealed pure titanium. It has been realized that the built-up edge (BUE) governs the material removal process of the rotating scratch. The current model makes use of the modification of BUE to the tool configuration so that the discretization of plastic region in the vicinity of the tool becomes feasible. The features of side-ridge and front-ridge, BUE and sub-layer plastic zone have been found to be evolving in different ways during the rotating scratch. Three material removal mechanisms were uncovered to be involved with the rotating scratch process, namely, plastic (shear) deformation, contact friction and ductile fracture. In the first-half of the scratch, the first two mechanisms dominate the process, while in the second-half, the ductile fracture plays an active role as evidenced by the extensive tearing along the both banks of scratch.