Characteristics of Corrosive Wear of TiN Coated High-speed Steel Wood Cutting Tools

摘要

To clarify the characteristics of corrosive wear of TiN coated high-speed steel tools in high moisture-content Douglas-fir (Pseudotsuga menziesii Franco) cutting, tool-life tests were conducted with a whirling disc-machine with four cutting speeds. The rake faces and the clearance faces of the tools were coated with TiN by physical vapor deposition (PVD) method, the thickness of thin-film for coated tool was 2-3 μm. In the tool-life tests for TiN coated tools and uncoated tools, the electrical-potential of +1kV, 0 V, or -1kV was applied to the tool by use of a direct-current power supply. The edge recession under 0 V for TiN coated tools progressed faster as cutting speed became faster, and progressed slightly faster than that of uncoated tools for each cutting speed. A little effect to lengthen the tool-life was recognized by coating the TiN. At the final cutting-length of 4 km, the edge recessions of both tools became the smallest under the cathode voltage of -1kV, due to the effect of cathodic protection, these values showed approximately 1/2-1/3 of those in normal cutting. The edge recessions of both tools became the largest under anode voltage of +1kV, these values showed approximately 4-5 times of those under zero voltage in normal cutting. The edge recessions for TiN coated tools under either cathode voltage or anode voltage became smaller than those of uncoated tools. The ratio of corrosive wear to the total edge recession under 0 V for uncoated tools was 45-60 %, and the value for TiN coated tools was 34-66 %.