A trigonal cutting insert for a shoulder milling tool includes an upper side, an opposite lower side and a peripheral side surface. A plurality of indexable cutting edges extend along corners of the cutting insert, each cutting edge having a main cutting edge, a corner cutting edge, and a surface-wiping secondary cutting edge. The upper side includes a recessed central surface, and a plurality of positively inclined rake surfaces having a main rake surface portion, a corner rake surface portion, and a secondary rake surface portion. A concave indentation is formed in the corner rake surface portion and in at least an initial part of the main rake surface portion adjacent to the corner rake surface portion, wherein the concave indentation has an elongated shape.

An example end mill includes a shaft, a cutting head positioned on one end of the shaft, and an edge relief cutting head positioned on the shaft spaced apart from the cutting head. The portion of the shaft between the cutting head and the edge relief cutting head has a diameter that is less than the diameters of the cutting head and the edge relief cutting head. The end mill is rotated around a longitudinal axis of the end mill and revolved around a central axis of a hole to be cut, with the longitudinal axis radially offset from the central axis, to cut the hole with the cutting head and cut an edge relief in a leading edge of the hole with the edge relief cutting head.

An example end mill includes a shaft, a cutting head positioned on one end of the shaft, and an edge relief cutting head positioned on the shaft spaced apart from the cutting head. The portion of the shaft between the cutting head and the edge relief cutting head has a diameter that is less than the diameters of the cutting head and the edge relief cutting head. The end mill is rotated around a longitudinal axis of the end mill and revolved around a central axis of a hole to be cut, with the longitudinal axis radially offset from the central axis, to cut the hole with the cutting head and cut an edge relief in a leading edge of the hole with the edge relief cutting head.

A cutter includes a rake face on which a recessed groove extending along a direction of a rotation axis of a rotary holder to be open at a flank face of the cutter are formed. The recessed groove includes a plurality of recessed grooves formed at predetermined intervals along a direction intersecting with the rotation axis. A cutting blade portion extending along a direction intersecting with the rotation axis is provided on a continuous portion of the rake face and the flank face. The cutting blade portion includes a first region made up of an intersecting portion of the rake face and the flank face and a second region made up of a peripheral edge portion of an opening portion of the recessed groove at the flank face.

A cutter includes a rake face on which a recessed groove extending along a direction of a rotation axis of a rotary holder to be open at a flank face of the cutter are formed. The recessed groove includes a plurality of recessed grooves formed at predetermined intervals along a direction intersecting with the rotation axis. A cutting blade portion extending along a direction intersecting with the rotation axis is provided on a continuous portion of the rake face and the flank face. The cutting blade portion includes a first region made up of an intersecting portion of the rake face and the flank face and a second region made up of a peripheral edge portion of an opening portion of the recessed groove at the flank face.

Provided is a cutting tool for a sputtering target that is used to chamfer a corner portion formed between a sputtering surface and a side surface of a sputtering target, into an R plane, the cutting tool comprising: a shaft portion; and a blade portion provided at a tip end of the shaft portion, wherein as viewed from a cross section along an axis of the shaft portion, the blade portion includes: a side surface extending along the axis; a leading end surface intersecting the axis; a main concave curved surface positioned between the side surface and the leading end surface, the main concave curved surface extending from a trailing end to a leading end; a first notched surface connected between the leading end of the main concave curved surface and the leading end surface; and a second notched surface connected between the trailing end of the main concave curved surface and the side surface.

Provided is a cutting tool for a sputtering target that is used to chamfer a corner portion formed between a sputtering surface and a side surface of a sputtering target, into an R plane, the cutting tool comprising: a shaft portion; and a blade portion provided at a tip end of the shaft portion, wherein as viewed from a cross section along an axis of the shaft portion, the blade portion includes: a side surface extending along the axis; a leading end surface intersecting the axis; a main concave curved surface positioned between the side surface and the leading end surface, the main concave curved surface extending from a trailing end to a leading end; a first notched surface connected between the leading end of the main concave curved surface and the leading end surface; and a second notched surface connected between the trailing end of the main concave curved surface and the side surface.

A rotatable tool for producing a circular groove through metal cutting in a metal work piece and a method of forming the circular groove with the rotatable tool is disclosed. The rotatable tool includes a front end and a second end. The front end includes a first radially outer cutting edge and a second radially inner cutting edge, where the first radially outer cutting edge is located at a larger radial distance from the tool center axis than any other cutting edge of the rotatable tool, and where the second radially inner cutting edge is located at a smaller radial distance from the tool center axis than any other cutting edge of the rotatable tool.

An end mill having a plurality of cutting edges on a surface of a rod-shaped main body is rotated about its longitudinal axis and is moved relative to a workpiece in a feed direction tangential and orthogonal to the longitudinal axis along the workpiece. The end mill is also moved relative to the workpiece in a reciprocal manner in the axial direction while it is moved in the feed direction. In this way, a plurality of dimples are formed by the end mill on the workpiece, such that the dimples are relatively spaced apart from each other on the workpiece. The plurality of dimples are arranged side by side in the feed direction along a line inclined at a predetermined angle relative to the feed direction so as to be offset while partially overlapping with respect to each other in the axial direction.

An end mill having a plurality of cutting edges on a surface of a rod-shaped main body is rotated about its longitudinal axis and is moved relative to a workpiece in a feed direction tangential and orthogonal to the longitudinal axis along the workpiece. The end mill is also moved relative to the workpiece in a reciprocal manner in the axial direction while it is moved in the feed direction. In this way, a plurality of dimples are formed by the end mill on the workpiece, such that the dimples are relatively spaced apart from each other on the workpiece. The plurality of dimples are arranged side by side in the feed direction along a line inclined at a predetermined angle relative to the feed direction so as to be offset while partially overlapping with respect to each other in the axial direction.