Multilayer coatings on tools for woodworking

This paper presents the results of modeling of CrCN/CrN and TiAlN/TiN multilayer coatings with a thickness of 3 μm, which consist of seven bilayers, each of the thickness of ca. 400 nm, and the thickness ratio of bilayers as 1:1 for both coatings, their deposition on the HS6-5-2 steel substrate using the cathodic arc evaporation method and the measurements of their mechanical properties. The mechanical properties of monolayer coatings, which are contained in the multilayer coatings were also examined. The coatings were investigated concerning the EDS hardness and adhesion. The coefficient of friction and the wear rate of the coatings were also measured. Further research includes the determination of the durability of tools for woodworking with wear resistant coatings. The coatings tested, both the multilayers and their components, are characterized by a good adhesion being not less than 80 N. The lowest wear rate is characterized by the CrCN/CrN multilayer coating (8.5 × 10−7 mm3 N−1 m−1), the TiAlN/TiN coating has a rate being 10 times higher. Among the tested coatings TiN coating shows the lowest coefficient of friction (0.4) but the wear rate is not the lowest. It is ca. 7 × 10−6 mm3 N−1 m−1 and is almost 5 times higher than for the CrCN coating. Industrial research of the “lifetime” of woodworking tools with wear resistant coatings was carried out in planer knives to the head. These tools with multilayer coatings exhibit more than a twofold increase in the work life of dry pine wood cutting. Both coatings show a similar increase of durability. Further sequential re-sharpening did not change significantly the lifetime of both knives.