A cutting tool includes a substrate and a diamond layer that covers the substrate. The diamond layer includes a rake face and a flank continuous to the rake face. A ridgeline between the rake face and the flank forms a cutting edge. The substrate includes a top surface opposed to the rake face. When viewed in a direction perpendicular to the top surface, the rake face includes a plurality of protrusions. In a cross-section perpendicular to a direction of extension of the cutting edge, each of the plurality of protrusions includes an inclined portion and a curvature portion continuous to the inclined portion. In the cross-section, a height of the inclined portion in the direction perpendicular to the top surface increases as a distance from the cutting edge increases.

A cutting tool having a cutting edge member which forms at least one corner part, wherein a material for the cutting edge member is selected from either diamond, an ultrahigh-pressure sintered body containing cubic boron nitride or a PVD or CVD coating applied to a surface of the ultrahigh-pressure sintered body. At least part of an intersecting edge between an end surface of the cutting edge member and a peripheral side surface thereof is provided with a cutting edge. A chip breaker comprising a breaker wall surface is formed in the end surface of the cutting edge member. The breaker wall surface has at least one projected surface part which bulges outwardly from the cutting tool. As viewed from the end surface, the recessed surface part is arranged so as to be apart from a virtual plane A which is defined so as to divide the corner part into halves.

A cutting element, which is configured for the machining of a non-metallic composite material composed of a matrix and particles held together by the matrix, has a flank face, a rake face and a cutting edge which is coated with an edge coating and via which the flank face and the rake face are connected to one another, with which the non-metallic composite material can be machined in an improved fashion. The cutting edge within a cutting edge section thereof is curved in such a way that the cutting edge immediately beneath the edge coating in a section in a section plane that is perpendicular to the cutting edge has, at every point of the cutting edge section, a local radius of curvature which is greater than or equal to 10 μm and less than or equal to 80 μm.

A coated tool, such as a rotating, cutting tool, includes a tool body and a multilayer wear protection coating system. The wear protection system coats a functional surface of the tool body that is subject to wear and includes a first undoped diamond layer and a second undoped diamond layer disposed over the first undoped diamond layer. The first undoped diamond layer is electrically conductive and exhibits grain boundary conductivity from delocalized electrons. The second undoped diamond layer is electrically insulating. The first undoped diamond layer is 4-20 microns thick and is made with diamond grains whose size ranges from 4-10 nm. The first and second diamond layers are applied by chemical vapor deposition (CVD) using a hot-wire method. The wear protection system also includes an additional undoped diamond layer that is electrically insulating and is disposed between the functional surface of the tool body and the first diamond layer.

A coated cutting tool for chip forming machining of metals includes a substrate having a surface coated with a chemical vapour deposition (CVD) coating. The coated cutting tool has a substrate coated with a coating including a layer of α-Al2O3, wherein the α-Al2O3 layer exhibits a dielectric loss of 10−6≦tan δ≦0.0025, as measured with AC at 10 kHz, 100 mV at room temperature of 20° C.

A surface-coated cutting tool with a hard coating layer is provided. The hard coating layer includes at least a complex nitride or carbonitride layer (2) expressed by a composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y)(C.sub.zN.sub.1-z), Me being an element selected from Si, Zr, B, V, and Cr. The average content ratio X.sub.avg, the average content ratio Y.sub.avg, and the average content ratio Z.sub.avg satisfy 0.60≦X.sub.avg, 0.005≦Y.sub.avg≦0.10, 0≦Z.sub.avg≦0.005, and 0.605≦x.sub.avg+y.sub.avg≦0.95. There are crystal grains having a cubic structure in the crystal grains constituting the complex nitride or carbonitride layer (2). A predetermined periodic content ratio change of Ti, Al and Me exists in the crystal grains having the cubic structure.

A cutting tool comprises a base material which includes particles including a tungsten carbide (WC) as a main component, a binder phase including cobalt (Co) as a main component, and particles including a carbide or a carbonitride of at least one selected from the group consisting of Group 4a, 5a, and 6a elements, or a solid solution thereof; and a hard film formed on the base material, wherein the hard film comprises at least an alumina layer, a cubic phase free layer (CFL), in which the carbide or the carbonitride is not formed, is formed from a surface of the base material to a depth of 10 μm to 50 μm, and a Co content of a surface of the CFL is 80% or more of a maximum Co content of the CFL.

A hard coating layer on a cutting tool includes at least a Ti and Al complex nitride or carbonitride layer and has an average layer thickness of 1 to 20 μm. In a case where a composition of the complex nitride or carbonitride layer is expressed by: (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y), a content ratio x and a content ratio y satisfy 0.60≦x≦0.95 and 0≦y≦0.005, where x and y are in atomic ratio. Crystal grains constituting the complex nitride or carbonitride layer include cubic phase crystal grains and hexagonal phase crystal grains. An area ratio occupied by the cubic phase crystal grains is 30-80%. An average grain width W is 0.05-1.0 μm. An average aspect ratio A of the crystal grains with the cubic grain structure is 5 or less. A periodic content ratio change of Ti and Al in (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y) exists in each of the cubic phase crystal grains.

A surface-coated cutting tool has a hard coating layer on a tool body. The hard coating layer includes a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer (the average amount Xavg of Al and the average amount Yavg of C satisfy 0.60≦Xavg≦0.95 and 0≦Yavg≦0.005). Crystal grains having an NaCl type face-centered cubic structure in the layer have {111} orientation, a columnar structure in which the average grain width of the individual crystal grains having an NaCl type face-centered cubic structure is 0.1 μm to 2.0 μm and the average aspect ratio is 2 to 10 is included, and in the individual crystal grains having an NaCl type face-centered cubic structure, a periodic compositional variation in Ti and Al in the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) is present and the difference between the average of maximum values of x and the average of minimum values thereof is 0.03 to 0.25.

Provided is a coated tool in which a hard coating layer has excellent hardness and toughness and exhibits chipping resistance and defect resistance during long-term use. The hard coating layer includes at least a layer of a complex nitride or complex carbonitride expressed by the composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y) (C.sub.zN.sub.1-x) (here, Me is one element selected from among Si, Zr, B, V, and Cr), an average amount Xavg of Al, an average amount Yavg of Me, and an average amount Zavg of C satisfy 0.60≦Xavg, 0.005≦Yavg≦0.10, 0≦Zavg≦0.005, and 0.605≦Xavg+Yavg≦0.95, crystal grains having a cubic structure are present in crystal grains constituting the layer of a complex nitride or complex carbonitride, and in the crystal grains having a cubic structure, a predetermined periodic concentration variation of Ti, Al, and Me is present, whereby the problems are solved.