A mounting seat bottom surface facing a holder rotation direction; a first mounting seat wall surface (3b) facing an outer peripheral side of the holder main body (1), and a first relief portion (3d) on a corner portion where they intersect, are formed on an outer peripheral portion of a tip of a holder main body (1) rotated in a direction around an axis, on the inner peripheral side of the first mounting seat wall surface (3b), an inclined face (6) is formed in a range from an end edge (3b1) of the first mounting seat wall surface (3b) to 2 mm or less in the inner peripheral side, and the inclined face (6) being retracted toward the posterior end side in the axial direction as being extended toward the inner peripheral side, and an inclination angle θ is 20° or more and 50° or less.

An end mill includes: a columnar tool body that rotates about a center axis; and outer peripheral cutting edges on an outer peripheral surface of the tool body, the outer peripheral cutting edges including a first outer peripheral cutting edge and a second outer peripheral cutting edge. A relief angle θ of the first outer peripheral cutting edge changes to increase in an axial direction of the tool body from a bottom face that is one end of the tool body. A relief angle θ of the second outer peripheral cutting edge changes to decrease in the axial direction from the bottom face.

A cutting insert includes an upper surface, a lower surface opposite to the upper surface, a first side surface and a second side surface configured to connect the upper surface and the lower surface, a mounting hole formed to penetrate the upper surface and the lower surface, a first cutting edge formed at an edge of the upper surface that meets the first side surface, and a second cutting edge formed at an edge of the upper surface that meets the second side surface. The lower surface includes a ridge portion, and a first inclined surface and a second inclined surface positioned on both sides of the ridge portion as a boundary. When looking at the lower surface, the first inclined surface and the second inclined surface have asymmetric shapes with respect to the ridge portion.

Disclosed is a radius end mill equipped with end cutting edges formed such that rotational locus thereof around an axial line draw a protruded curved face. That is, the protruded curved face is formed so as to have a protruded curved face where a curvature radius in an inner portion located closer to an axial line side than a tip outer-peripheral side of an end mill body is greater than a curvature radius on the tip outer-peripheral side, in a sectional view along the axial line. A gash depth angle θ(°) calculated by θ=tan.sup.−1 (A/B) on the basis of a distance A in an axial direction from a protruded end of an end cutting edge to a most-posterior end of a gash and a radius B from the axial line to a contact point between a peripheral cutting edge and the end cutting edge is set to be 50° or less.

A milling tool having a radial cutting edge for milling high-feed rates. The radial cutting edge having first, second and third sub-edges which extend at angles which are relatively small when formed with a longitudinal axis AL of the milling tool, thereby allowing the high-feed rates.

A milling tool having a radial cutting edge for milling high-feed rates. The radial cutting edge having first, second and third sub-edges which extend at angles which are relatively small when formed with a longitudinal axis AL of the milling tool, thereby allowing the high-feed rates.

A rotary cutting tool includes a shank portion, a cutting portion, and a cutting tip. The cutting portion includes a plurality of blades and a plurality of flutes. Each blade includes a leading face, a trailing face, and a land surface extending between the leading face and the trailing face. The cutting end includes an end cutting edge having a first end face cutting edge portion formed with a positive, neutral or negative radial angle, a positive dish angle and a negative axial rake angle, and second end face cutting edge portion formed with a highly positive radial angle, a positive dish angle and a negative axial rake angle. The highly positive radial angle of the second end face cutting edge portion enables the rotary cutting tool to perform a ramp operation at very large ramp angles of between about 15-45 degrees.

An end mill includes: a columnar tool body that rotates about a center axis; and outer peripheral cutting edges on an outer peripheral surface of the tool body, the outer peripheral cutting edges including a first outer peripheral cutting edge and a second outer peripheral cutting edge. A relief angle of the first outer peripheral cutting edge changes to increase in an axial direction of the tool body from a bottom face that is one end of the tool body. A relief angle of the second outer peripheral cutting edge changes to decrease in the axial direction from the bottom face.

A rotary cutting tool includes a shank portion, a cutting portion, and a cutting tip. The cutting portion includes a plurality of blades and a plurality of flutes. Each blade includes a leading face, a trailing face, and a land surface extending between the leading face and the trailing face. The cutting end includes an end cutting edge having a first end face cutting edge portion formed with a positive, neutral or negative radial angle, a positive dish angle and a negative axial rake angle, and second end face cutting edge portion formed with a highly positive radial angle, a positive dish angle and a negative axial rake angle. The highly positive radial angle of the second end face cutting edge portion enables the rotary cutting tool to perform a ramp operation at very large ramp angles of between about 15-45 degrees.

An object of the present invention is to provide helically fluted end mill with a diamond cutting surface. More particularly, it is an object of the present invention to provide a helically fluted end mill with helical grooves in the flutes that are filled with compacted polycrystalline diamond that can provide an effective cutting length based on the appropriate relationship between cutting length, diameter, the number of flutes, angle, and the number of polycrystalline diamond segments per flute.