THE CUTTING PERFORMANCE OF A TIN-COATED DRILL WITH CURVED PRIMARY CUTTING EDGES

In this paper an investigation of the cutting performance of a TiN-coated drill with curved primary cutting edges is reported. The curved primary cutting edge is determined mathematically by changing the distribution of the orthogonal rake angle along the primary cutting edge. The drills are coated with a 2-4 mu m thick, titanium nitride layer (TiN) by a commercial facility using a physical vapor deposition (PVD) process. Experiments have been conducted to evaluate the cutting performance. In comparison with uncoated drills with straight (and curved) primary cutting edges which had the same web thickness, the experimental results show that a TiN-coated drill with curved primary cutting edges is effective in reducing the thrust forces, the torque, and the tool wear, which definitely provides a better cutting ability and a longer tool life.