Abstract
Polycrystalline cubic boron nitride compact (cBN) tools are widely used for cutting hardened steel, due to their higher hardness and higher thermal conductivity. However, in higher feed rate cutting, fracture of the cBN cutting tool occurs easily because it has poor fracture toughness. Coated cemented carbide tools, which have good fracture toughness and wear resistance, seem to be effective tool materials in the higher feed rate cutting of hardened steel.
In this study, hardened steel (SKD11, 60HRC) was cut with three physical vapor deposition (PVD) coated cemented carbide tools in order to investigate effective tool materials for cutting hardened steel at high feed rate cutting. The coating films used were (Ti, Al)N, (Ti, W, Si)N and (Ti, W)N/(Ti, W, Si)N coating film.
The following results were obtained: (1) In turning hardened steel, the wear progress of the (Ti, W)N/(Ti, W, Si)N coated tool was slower than that of the (Ti, Al)N or (Ti, W, Si)N coated tool. (2) In milling hardened steel, the (Ti, W)N/(Ti, W, Si)N coated cemented carbide was an effective tool material for high speed cutting below a cutting speed of 2.5 m/s.
