Patent ID: 7736733

Claim:
A round cutting insert for train wheels with a ceramic film formed on a substrate wherein: said substrate is formed from a hard phase and a binder phase, said hard phase being formed from WC and at least one metal compound selected from the group consisting of: a non-WC carbide, a nitride, and a carbonitride of a periodic table group 4a, 5a, 6a metal; and said binder phase being formed from at least one type of transition metal; in said hard phase, a total volume of said metal compound has a proportion of 1.5-20% relative to a volume of said WC, and an average grain size of said WC is 1-5 microns; said binder phase contains at least Co and a volume of said binder phase relative to a total volume of said substrate is 7-20%; said substrate includes a ridge line of a cutting edge with a honed section, a base face and a breaker disposed on a rake face connected to said ridge line of said cutting edge, and an insert hole for securing to a holder; round honing or combination honing is performed on said honed section and a nose radius is at least 1.6 mm; said ceramic film includes an a-type aluminum oxide film, and at least one compound film selected from the group consisting of: a carbide, a nitride, an oxide, a carbonitride, an oxycarbide, a carbon oxynitride, a boron nitride, and a boron carbon oxynitride of a periodic table group 4a, 5a, 6a metal and an aluminum oxide; said a-type aluminum oxide film has a thickness of 2-12 microns; grains with grain sizes of 3-5 microns are present over 5-80% of the area of the a-type aluminum oxide film surface; the over-all thickness of the ceramic film is 3-25 microns; a ten-point average surface roughness Rz (5 microns reference length) of an inside of said honed section, a flank face side of said honed section, and a rake face side of said honed section is no more than 0.2 microns; and a ten-point average surface roughness Rz (5 microns reference length) at an upper section of said breaker, said base face, and an area around said insert hole is no more than 0.5 microns.