The Role of Thin-Film Vacuum-Plasma Coatings and Their Influence on the Efficiency of Ceramic Cutting Inserts

Abstract

The main problem with ceramics used in cutting tools is related to the unpredictable failures caused by the brittle fracturing of ceramic inserts, which is critical for the intermittent milling of cyclic loading. A 125-mm-diameter eight-toothed end mill, with a mechanical fastening of ceramic inserts, was used as a cutting tool for milling hardened steel (102Cr6). For the experiments, square inserts of the Al2O3 + SiC ceramic were used and compared with the samples made of Al2O3 + TiC to confirm the obtained results. The samples were coated with diamond-like coating (DLC), TiZrN, and TiCrAlN coatings, and their bending strength and adhesion were investigated. Investigations into the friction coefficient of the samples and operational tests were also carried out. The effect of smoothing the microroughness and surface defects in comparison with uncoated inserts, which are characteristic of the abrasive processing of ceramics, was investigated and analyzed. The process developed by the authors of the coating process allows for the cleaning and activation of the surface of ceramic inserts using high-energy gas atoms. The impact of these particles on the cutting edge of the insert ensures its sharpening and reduces the radius of curvature of its cutting edges.