ST4, a new super tough PVD coated carbide grade released by NTK Cutting Tools. The thick CrAlN coating provides high hardness and oxidation resistance solving issues related to machining materials such as: 304SS, 17-4PH, and Nitinol. High speed machining applications with ST4 inserts have proven results with stable machining, excellent surface finishes, and extended tool life. This super tough coating combined with NTK's top of the line chip-breakers for front turning, back turning, grooving, cut-off, and ID turning will exceed your machining expectations.