A cutting tool is a cutting tool comprising a substrate and a coating film disposed on the substrate, in which the coating film includes a first layer, the first layer is composed of an alternate layer where a first unit layer and a second unit layer are alternately stacked, the first unit layer is composed of Ti.sub.1-a-bAl.sub.aCe.sub.bN, a is 0.350 or more and 0.650 or less, b is 0.001 or more and 0.100 or less, the second unit layer is composed of Al.sub.cCr.sub.1-cN, c is 0.40 or more and 0.75 or less, and a and c satisfy a relationship of c>a.

A cutting tool includes: a rake face; a flank face continuous to the rake face; and a cutting edge formed by a ridgeline between the rake face and the flank face. The cutting tool includes: a base material having a first face on a side of the rake face and a second face on a side of the flank face; and a diamond layer covering the first face and the second face. The first face includes: a first top face continuous to the second face; and a second top face continuous to the first top face and disposed such that the first top face is sandwiched between the second top face and the second face. An angle formed between the first top face and the second top face is a negative angle in a cross section perpendicular to the cutting edge.

A coated cutting tool comprises a substrate and a coating layer and the coating layer comprises a first laminate structure and a second laminate structure and each of the first laminate structure and the second laminate structure is laminated in an alternating manner and the number of laminations is three or more and one compound layer and other compound layer of the compound layers of two kinds in the each of the first laminate structure and the second laminate structure has a specific composition and the first laminate structure and each of the second laminate structure satisfies a specific condition and an average thickness of each of the layers constituting the first laminate structure and the second laminate structure and an average thickness of the coating layer is respectively a specific one.

The drill has a rake face, a flank face, and an outer circumferential surface. The flank face is continuous to the rake face. The outer circumferential surface is continuous to both the rake face and the flank face. A ridgeline between the rake face and the flank face constitutes a cutting edge. A ridgeline between the rake face and the outer circumferential surface constitutes an outer circumferential end. A groove is provided cyclically in the rake face to extend at an angle relative to an axis of the drill, the angle being larger than a helix angle of the drill. The groove has a depth of more than or equal to 1.5 m.

A surface-coated cutting tool includes a base material and a coating formed on a surface of the base material. The coating includes a first hard coating layer including crystal grains having a sodium chloride-type crystal structure. The crystal grain has a layered structure in which a first layer composed of nitride or carbonitride of Al.sub.xTi.sub.1-x and a second layer composed of nitride or carbonitride of Al.sub.yTi.sub.1-y are stacked alternately into one or more layers. The first layer each has an atomic ratio x of Al varying in a range of 0.6 or more to less than 1. The second layer each has an atomic ratio y of Al varying in a range of 0.45 or more to less than 0.6. The largest value of difference between the atomic ratio x and the atomic ratio y is 0.05xy0.5.

A surface-coated cutting tool includes a base material and a coating formed on a surface of the base material. The coating includes a first hard coating layer including crystal grains having a sodium chloride-type crystal structure. The crystal grain has a layered structure in which a first layer composed of nitride or carbonitride of AlxTi1x and a second layer composed of nitride or carbonitride of AlyTi1y are stacked alternately into one or more layers. The first layer each has an atomic ratio x of Al varying in a range of 0.6 or more to less than 1. The second layer each has an atomic ratio y of Al varying in a range of 0.45 or more to less than 0.6. The largest value of difference between the atomic ratio x and the atomic ratio y is 0.05xy0.5.

The diamond coated tool of the present invention is a diamond coated tool including a base material and a diamond layer coating a surface of the base material, and characterized in that the surface of the base material has an arithmetic average roughness Ra of not less than 0.1 m and not more than 10 m and an average length of roughness profile elements RSm of not less than 3.1 m and not more than 5.4 m, and that the diamond layer has a plurality of cavities at a portion bordering on the base material.

A coated cutting tool comprises a substrate and a coating layer and the coating layer comprises a first laminate structure and a second laminate structure and each of the first laminate structure and the second laminate structure is laminated in an alternating manner and the number of laminations is three or more and one compound layer and other compound layer of the compound layers of two kinds in the each of the first laminate structure and the second laminate structure has a specific composition and the first laminate structure and each of the second laminate structure satisfies a specific condition and an average thickness of each of the layers constituting the first laminate structure and the second laminate structure and an average thickness of the coating layer is respectively a specific one.

In an embodiment, a cutting insert including a base member, a first face, a second face, a cutting edge, and a nose portion. The base member includes a coating layer on at least a part thereof. The first face has corner portions. The second face is adjacent to the first face. The cutting edge is on at least a part of the ridgeline portion of the first face and the second face, and includes first and second cutting edges. The first cutting edge is on the coating layer and has a C chamfered surface with a first width of 5 m to 30 m in the front view of the first face and a chamfer angle of 35 to 50. The nose portion is at the corner portions between the first cutting edge and the second cutting edge.

The strength of the bond formed by a braze material between a polycrystalline hard material and a hard composite may be physically strengthened. For example, a method of physical strengthening may include etching a bonding surface of a polycrystalline material body to produce a synthetic topography on the bonding surface of the polycrystalline material body, the bonding surface opposing a contact surface of the polycrystalline material body; and brazing the bonding surface of the polycrystalline material body having the synthetic topography to a bonding surface of a hard composite using a braze material.