An insert based on an aspect includes a first face, a second face located opposite to the first face, a third face located between the first face and the second face, and a cutting edge located on an intersection of the first face and the third face. The first face includes a first region inclined so as be close to the second face as being separated away from the cutting edge. A virtual straight line orthogonal to the cutting edge is set as a first virtual straight line in a front view of the first face. A ten-point average of roughness the first region in a direction along the first virtual straight line is expressed by Rz1a and a ten-point average of roughness of the first region in a direction along the cutting edge is expressed by Rz1b, and Rz1a is larger than Rz1b.

Tool holder has a first section adapted to be connected to a machining center and a tool holding section comprising a bore with a surface defining an inner diameter of the bore. Dispersed around the surface of the bore and at least partially embedded in the surface of the bore is a joining compound having a Young's modulus greater than a Young's modulus of the surface of the bore.

An insert based on an aspect includes a first face, a second face located opposite to the first face, a third face located between the first face and the second face, and a cutting edge located on an intersection of the first face and the third face. The first face includes a first region inclined so as be close to the second face as being separated away from the cutting edge. A virtual straight line orthogonal to the cutting edge is set as a first virtual straight line in a front view of the first face. A ten-point average of roughness the first region in a direction along the first virtual straight line is expressed by Rz1a and a ten-point average of roughness of the first region in a direction along the cutting edge is expressed by Rz1b, and Rz1a is larger than Rz1b.

Tool holder has a first section adapted to be connected to a machining center and a tool holding section comprising a bore with a surface defining an inner diameter of the bore. Dispersed around the surface of the bore and at least partially embedded in the surface of the bore is a joining compound having a Young's modulus greater than a Young's modulus of the surface of the bore.

A rotating cutting tool having a shank composed of siliconized silicon carbide (SiSiC), and a diamond cutting head that is mechanically connected to and in thermal communication with the shank via a vacuum-brazed thermal interface.

A cutting tool comprising a base material and a coating, wherein the coating comprises a hard particle layer, the hard particle comprises a multilayer structure in which a first unit layer formed from a first compound and a second unit layer from a second compound are alternately stacked, each of the first compound and the second compound consists of one or more metal elements selected from the group consisting of a periodic table group 4 element, a periodic table group 5 element, and a periodic table group 6 element, silicon, and one or more elements selected from the group consisting of carbon, nitrogen, boron, and oxygen, and a percentage of the number of atoms of the silicon to a sum of the numbers of atoms of the metal element and the silicon in the first unit layer is different from that in the second unit layer.