Structure and properties of cathodic arc ion plated CrN coatings for copper machining cutting tools

Cathodic arc ion plated chromium nitride (CrN) coatings were deposited on WC–Co substrates at negative substrate bias voltages in a range from 0 to 200 V. The properties of CrN coatings were investigated, including the structure, hardness, adhesion and residual stress. The performance of cutting tests of CrN-coated endmills in copper was also investigated correlating with the properties. At a negative substrate bias voltage of 30 V, the adhesion strength of the coating was maximized, and the grain size became relatively small. The endmill deposited at the same bias voltage exhibited the best cutting performance of all the other samples. The cutting performance of CrN-coated endmills were superior to that of (Ti,Al)N coated endmills or uncoated endmills. The relationships between the cutting performance and film properties were discussed in terms of the wear system of the cutting tools.