Influence of Thickness of Multilayered Nano-Structured Coatings Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrCrNbAl)N on Tool Life of Metal Cutting Tools at Various Cutting Speeds

• Main Authors: Alexey Vereschaka, Elena Kataeva, Nikolay Sitnikov, Anatoliy Aksenenko, Gaik Oganyan, Catherine Sotova
• Format: Article
• Language: English
• Published: MDPI AG 2018-01-01
• Series: Coatings
• Subjects: multilayered nano-structured coatings; tool life; metal cutting tools; scratch testing
• Online Access: http://www.mdpi.com/2079-6412/8/1/44

This paper considers the influence of thickness of multilayered nano-structured coatings Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrCrNbAl)N on tool life of metal cutting tools at various cutting speeds (vc = 250, 300, 350 and 400 m·min−1). The paper investigates the basic mechanical parameters of coatings and the mechanism of coating failure in scratch testing depending on thickness of coating. Cutting tests were conducted in longitudinal turning of steel C45 with tools with the coatings under study of various thicknesses (3, 5, and 7 µm), with an uncoated tool and with a tool with a “reference” coating of TiAlN. The relationship of “cutting speed vc—tool life T” was built and investigated; and the mechanisms were found to determine the selection of the optimum coating thickness at various cutting speeds. Advantages of cutting tools with these coatings are especially obvious at high cutting speeds (in particular, vc = 400 m·min−1). If at lower cutting speeds, the longest tool life is shown by tools with thicker coatings (of about 7 μm), then with an increase in cutting speed (especially at vc = 400 m·min−1) the longest tool life is shown by tools with thinner coating (of about 3 μm).