Improving the Efficiency of the Cutting Tool Made of Ceramic when Machining Hardened Steel by Applying Nano-Dispersed Multi-Layered Coatings <sup></sup>

The functional role of nano-dispersed multi-layered composite coatings (NMCC) deposited on the working surfaces of cutting inserts (CI) made of the layered high-strength ceramic (LHC) to equip the cutting tools when cutting hardened (high-strength) steels was investigated. It is shown that the variation in the composition, structure and properties of coatings allows controlling the contact processes at cutting, increasing the length of contact, reducing normal contact stresses and probability of micro- and macro-brittle failure of tool cutting edge. The mathematical models of cutting which establish dependences of flank wear land of the tool, the tangential component of cutting force, power of cutting and roughness of the machined surface from conditions of cutting of high-strengthen steels are developed. It is found out that the application of nano-dispersed ceramic multi-layered coatings on ceramic tool significantly increases its wear resistance and improves the quality of machining.