CrxNy hard coatings deposited with PVD method on tools for wood machining

Although well known and widely used, tools modified with hard coatings are still not applied to the wood industry. Difficulties come from mechanical, physical and tribological properties of wood and of wood based materials to gether with particular parameters of their processing. The aim of this stud y was to synthesise hexagonal and cubic chromium nitride coatings and apply them in wood processing to improve cutting tools' wear resistance. The app aratus used was an industrial type router. The material subjected to cuttin g was OSB (Oriented Strand Board). The cutting tools with an edge angle of 55 degrees were cemented carbide inserts. The coatings were deposited by tr iode sputtering system; the hexagonal phase was obtained for 10% of nitroge n in the Ar + N-2 mixture used in the discharge, the cubic one was obtained for a percentage higher than 20%. The composition of coatings was determin ed by EDS and WDS microanalysis and SEM cross-section observations were per formed. The mechanical properties of layers were determined by stress measu rements and by a wear test performed with in situ method. It reveals that t he most resistant coatings are the Cr2N films. These optimal conditions of deposition have been applied to cutting tools in routing process. It appear s that CrN or Cr2N coatings deposited on both tools' faces ameliorate signi ficantly tools wear resistance. (C) 2000 Elsevier Science B.V. All rights r eserved.