Provided is a coated cutting tool in which a surface of a substrate is coated with a hard coating film. The hard coating film includes: a layer (A) disposed on the surface of the substrate, and having a face-centered cubic lattice structure, in which the total content ratio of W and Ti is at least 85 atomic %, and which contains W as the most abundant element and Ti as the next most abundant element among metal (including metalloid) elements; and a layer (B) disposed on the layer (A) and having a face-centered cubic lattice structure, which is composed of nitrides or carbonitrides containing Al, Cr, and Si, and in which, among metal (including metalloid) elements, the Al content ratio is at least 50 atomic %, the total content ratio of Al and Cr is at least 85 atomic %, and the Si content ratio is 4 to 15 atomic %.

A cutter holder has a body, a fastening bolt, and a vibration absorbing structure. The body has a specific weight. The fastening bolt is mounted inside the body. The vibration absorbing structure is mounted inside the body and has a sleeve, an elastic unit, a spacer, and a set nut. The sleeve is mounted around the fastening bolt and has a specific weight. The specific weight of the sleeve is larger than the specific weight of the body. The elastic unit is mounted around the fastening bolt and has two opposite ends. One of the ends of the elastic unit abuts against the sleeve. The spacer is mounted around the fastening bolt and abuts against the other end of the elastic unit. The set nut is screwed with the fastening bolt and abuts against the spacer.

An insert includes a base. The base includes first and second surfaces, and a cutting edge on at least a part of a ridgeline of the first and second surfaces. The first surface includes a groove away from the ridgeline and at an angle θ1 of 20-90° relative to the ridgeline. The groove extends from a first end part closest to the cutting edge to a second end part most away from the cutting edge. The groove includes an opening and a bottom surface. An angle θ2 formed by the bottom surface and a raised surface extended from the bottom surface toward the first end part is 95-135°. A cutting tool includes a holder, which has a length extending from a first end to a second end and includes a pocket located on a side of the first end, and the insert located in the pocket.

A diamond cutting tool comprises a base metal part and a diamond part joined to the base metal part, wherein the base metal part is made of an alloy containing tungsten carbide, the diamond part configures at least a cutting blade, the cutting blade comprises a portion of a rake face, a portion of a flank face, and a ridge line at which the rake face and the flank face cross, the diamond cutting tool has a region A, the region A is a region that is present bridging over the three, which are the rake face, the ridge line, and the flank face on the surface of the cutting blade, and the region A has a surface roughness Ra of not more than 0.2 μm and a concentration of tungsten element of not more than 1 mass %.

A cutting insert according to an aspect includes a base portion and a cutting portion. The cutting portion includes an upper surface, a side surface, a ridge line including a first ridge line and a second ridge line, and an intersection point. The upper surface includes a top surface region and a rising surface region located between the top surface and the ridge line, and having a shape protruding toward the intersection point. In a top view, a first distance from the first ridge line to the rising surface increases as close to the intersection point, and a second distance from the second ridge line to the rising surface increases as close to the intersection point.

A drill bit includes a bit body; a plurality of gouging cutters rotatably mounted to the bit body so as to define a first profile; and a plurality of gouging cutters non-rotatably mounted to the bit body so as to define a second profile. The first profile is longitudinally ahead of the second profile in a direction of drilling of the drill bit by a selected distance.

A cutting insert according to an aspect includes a base portion and a cutting portion. The cutting portion includes an upper surface, a side surface, a ridge line including a first ridge line and a second ridge line, and an intersection point. The upper surface includes a top surface region and a rising surface region located between the top surface and the ridge line, and having a shape protruding toward the intersection point. In a top view, a first distance from the first ridge line to the rising surface increases as close to the intersection point, and a second distance from the second ridge line to the rising surface increases as close to the intersection point.

A drill bit includes a bit body; a plurality of gouging cutters rotatably mounted to the bit body so as to define a first profile; and a plurality of gouging cutters non-rotatably mounted to the bit body so as to define a second profile. The first profile is longitudinally ahead of the second profile in a direction of drilling of the drill bit by a selected distance.

In a surface-coated cutting tool, a hard coating includes one or more layers. At least one layer thereof is a hard coating layer composed of a complex nitride or carbonitride layer of Al, Cr, and Si and satisfying (Al.sub.1-x-yCr.sub.xSi.sub.y)(C.sub.zN.sub.1-z) where x, y and z are atomic ratios and satisfy 0.1x0.4, 0.01y0.2, and 0z0.3, respectively. The hard coating layer contains particles including: less than 10 atomic % of non-metal components selected from C and N; and metal components selected from Cr, Al and Si. In the cross-section perpendicular to the tool body surface, the number ratio of oblate particles with an Al content of 50 atomic % or less, a long diameter of less than 0.5 m, and an aspect ratio of 2.0 or more is 90% or more with respect to the total number of the particles.

A rod, a cutting tool and a method for manufacturing a cutting tool are disclosed. In an embodiment, the rod may include a cemented carbide member containing WC and Co. The cemented carbide member may be elongated and include a first end portion and a second end portion in a longitudinal direction. The first end portion may have a Co content Co.sub.AC smaller than a Co content Co.sub.BC of the second end portion. The cemented carbide member may include a first portion on a side of the first end portion and a second portion on a side of the second end portion. The first portion may have a gradient S.sub.1 representing a change in a Co content per millimeter. The second portion may have a gradient S.sub.2 representing a change in a Co content per millimeter. The gradient S.sub.1 may be greater than the gradient S.sub.2.