Mechanical properties and cutting performance of Cr–Al–N hybrid coated micro-tool for micro high-speed machining of flexible fine die

In this paper, comparative studies on mechanical properties and cutting performance between CrN and Cr–Al–N coatings for high-speed machining of flexible fine die (FFD) were conducted. Ternary Cr–Al–N coatings, in which Al was incorporated into CrN, were synthesized onto WC–Co substrates using a hybrid coating system of arc ion plating and sputtering techniques. From XRD analysis the nanocomposite Cr–Al–N coatings were related to the composite microstructure consisting of the fine CrN crystallites and amorphous Si3N4. The average friction coefficient of Cr–Al–N coatings gradually decreased with Al content in CrN coatings. The values of tool wear for uncoated, CrN and Cr–Al–N coated tools were evaluated under a high-speed cutting condition using a vertical high-speed machining center. Consequently, the ternary Cr–Al–N coated micro-tool showed good cutting performance under micro high-speed machining of AISI W1-8 steel of hardness 52 HRC for flexible fine die.