Antiabrasive coatings: application for wood processing

The aim of the study was to examine how a modification of the tool surface influences the knives blunting for wood processing. The process was conducted with a laboratory Micro-lathe test apparatus. The cutting tools used in the experiments had an edge angle of 20 degrees and were made of 60SMD8 low-alloy steel and Z90WDCV high-speed steel. The modification of the working surface of the tool involved covering it with antiabrasive coatings: TiN, (Ti,Zr)N, CrXNY W-C:H(DLC) and Cr. 60SMD8 steel was also nitrided. The lowest reduction of the cutting edge has been observed for CrXNY coated knives. The CrXNY coated knives seemed to have the best adhesion to steel: resisting scratching Lip to 4000 m of the cutting path. The obtained results demonstrate that the modification of a knife with hard coatings delays drawbacks of a knife wearing out processes. The relatively high values of friction coefficient between coatings and wet wood (up to 0.4) require a very large extent of adhesion between coatings and tools surfaces. It seems that for wood rotary peeling with a knife with an edge angle of 20 degrees, it is not enough to increase the edge hardness but it also needs a complete study of the geometry of the edge. It appears that a low value of friction, a good resistance to abrasion and, to some extent, a good adhesion between a coating and a steel knife are the most important factors in wood knife modification. (C) 1999 Elsevier Science S.A. All rights reserved.