A surface coated cutting tool comprises: a tool substrate and a coating layer on a surface of the tool substrate; wherein the coating layer comprises a lower layer, an intermediate layer, and an upper layer, in sequence from the tool substrate toward the surface of the tool. The lower layer comprises an A layer having an average composition represented by formula: (Al.sub.1-xCr.sub.x)N, where x is 0.20 to 0.60; the intermediate layer comprises a B layer having an average composition represented by formula: (Al.sub.1-a-bCr.sub.aSi.sub.b)N, where a is 0.20 to 0.60 and b is 0.01 to 0.20; and the upper layer comprises a C layer having an average composition represented by formula: (Ti.sub.1-α-βSi.sub.αW.sub.β)N where α is 0.01 to 0.20 and β is 0.01 to 0.10; and the upper layer has a repeated variation in W level with an average interval of 1 nm to 100 nm between adjacent local maxima and minima.

The present invention provides a diamond coated tool which is resistant to exfoliation at an interface between a base material and a diamond layer. 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 μm and not more than 10 μm and an average length of roughness profile elements RSm of not less than 1 μm and not more than 100 μm, and that the diamond layer has a plurality of cavities extending from a portion bordering on the base material in a crystal growth direction.

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 μm and not more than 10 μm and an average length of roughness profile elements RSm of not less than 3.1 μm and not more than 5.4 μm, and that the diamond layer has a plurality of cavities at a portion bordering on the base material.

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.

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 μm.

In a diamond-coated tool, a flank face of a tool base material includes a first flank face continuously extending to a cutting edge, a second flank face located farther away from the cutting edge than the first flank face and located outside the first flank face when viewed from an inside of the tool base material, and a flank face-side stepped portion connecting the first flank face and the second flank face. A diamond-coated layer is provided on the first flank face and the flank face-side stepped portion.

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 μm to 30 μm 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.

A coated tool include a first surface, a second surface which is adjacent to the first surface, and a cutting edge which is located on at least a portion of a ridge between the first surface and the second surface. The coated tool further includes a substrate, and a coating layer that is located on the substrate. The coating layer includes a titanium carbonitride layer and an aluminum oxide layer which has an -type crystalline structure. The titanium carbonitride layer is located nearer to the substrate than the aluminum oxide layer. When a value represented by the following equation is taken to be an orientation factor Tc(hkl) on the basis of peaks of the aluminum oxide layer analyzed by X-ray diffraction analysis, a ratio (Tcf(104)/Tcf(012)) of orientation factors Tcf(104) to Tcf(012) of the coating layer on the second surface is higher than a ratio (Tcr(104)/Tcr(012)) of orientation factors Tcr(104) and Tcr(012) of the coating layer on the first surface: Tc(hkl)={I(hkl)/I.sub.0(hkl)}/[(1/7){I(HKL)/I.sub.0 (HKL)}].

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, the coating layer including at least one -type aluminum oxide layer, wherein, in the -type aluminum oxide layer, a texture coefficient TC (1,0,16) of a (1,0,16) plane is 1.4 or more.