In an embodiment, a cutting tool includes a holder and a cutting insert. The holder is elongated, extends from a first end to a second end along a rotational axis. The holder includes an insert pocket on a side of the first end. The cutting insert is located in the insert pocket and includes a cutting edge. The insert pocket includes an opening in an end surface of the first end and an outer peripheral surface adjacent to the first end of the holder. The cutting insert further includes a first portion that is located more radially inward than an outer peripheral opening of in the insert pocket in a front view of the first end of the holder. The first portion has a width greater than a width of the opening in a direction along a rotation direction of the rotation axis.

An end mill includes a body including an axis, first cutting edges on a side of a front end of the body, second cutting edges at a rear side of the respective first cutting edges, flutes located along the second cutting edges, and heels located along the flutes. A shape of each of the flutes in a cross section includes a first concave curve on a side of the second cutting edges, a second concave curve on a side of the heels, and a protrusion located between the two concave curves, the protrusion includes two concave curves intersect each other, and a ratio of a distance from a circle including a maximum diameter in the body centered on the axis to a top of the protrusion to a distance H from the circle to the second cutting edge is 0.1 to 0.4.

In an embodiment, a cutting tool includes a holder and a cutting insert. The holder is elongated and includes an insert pocket that is located on a side of a first end. The cutting insert is secured to the insert pocket. The cutting tool further includes a clamp that fastens the cutting insert in the insert pocket, and a screw that comes in contact with the cutting insert and is secured to the insert pocket. The screw includes a first surface including a first engagement portion on a first surface that is located on a side of the first end. The first engagement portion is located within a through-hole included in the screw in a front view of the first end.

In one embodiment, a holder includes a body part elongated from a first end part to a second end part along a rotation axis. The body part includes a first member, a second member, and a third member. The first member is located on a side of the first end part, and includes a pocket to receive a cutting insert. The second member is located closer to the second end part than the first member, and includes at least one cavity inside the second member. The third member is located closer to the second end part than the second member.

An end mill includes a plurality of teeth and flutes. The teeth and their associated flutes include one or more correlated physical parameters. One such correlated parameter is that, at an axial location in a front half of an effective cutting length, at least one tooth of the plurality of teeth has a rake angle smaller than an average rake angle value of the plurality of teeth, and, at the same axial location, a flute preceding each such tooth has a helix angle larger than an average helix angle value of the plurality of flutes.

A replaceable cutting head stably rotates a head body using a work tool during attachment. An outer periphery of the head body is provided with a plurality of chip discharge grooves extending along a direction of an axis, cutting blades extending along the chip discharge grooves, and a pair of latching faces that are formed by cutting the outer periphery of the head body and are arranged back to back with the axis interposed therebetween at a base end portion along the axial direction. A first chip discharge groove, and a second chip discharge groove having a narrower width along a circumferential direction around the axis than the first chip discharge groove at at least the base end portion along the direction of the axis are included in the chip discharge grooves. At least one latching face is connected to a base end portion of the second chip discharge groove.

A rotating tool includes a tool body which rotates around an axial line, four or more chip discharge grooves which are formed on an outer periphery of the tool body with gaps therebetween in a circumferential direction, and a plurality of cutting inserts which are arranged in multiple stages along the chip discharge grooves. In a cross-sectional view perpendicular to the axial line, when a center angle formed between a pair of virtual straight lines which connects each of the cutting edges of the cutting inserts disposed in a pair of chip discharge grooves adjacent to each other in the circumferential direction and the axial line to each other is defined as an angle, a plurality of angles formed around the axial line include one maximum angle (max), one minimum angle (min), and two or more angles other than the angle (max) and the angle (min).

Described is an end mill with four straight front cutting edges arranged on a front side and a corresponding number of circumferential cutting edges that each emanate from the outer nose of the front cutting edges and are separated from each other by flutes. One of the front cutting edges passes over into a second cutting edge via a free surface intersecting line. The additional front cutting edges lying between the latter in the cutting direction are offset relative to each other by a first angular pitch of 180, and end before the middle. So that the end mill can be used in an especially advantageous manner for incorporating dimensionally and positionally precise pilot holes or chamfering curved work piece surfaces, the first front cutting edge is offset relative to the second front cutting edge in the cutting direction by a second angular pitch ranging between 173 and 177, preferably between 174 and 176, wherein the first front cutting edge is offset relative to the next additional front cutting edge in the cutting direction by a third angular pitch ranging between 90 and 94, preferably between 91 and 93.

A rotary cutting tool with a longitudinal axis includes a shank portion and a cutting portion defining a length of cut. The cutting portion includes a plurality of blades separated by flutes extending along the length of cut. A first blade forms a first helix angle with respect to the longitudinal axis at the cutting tip. A second blade adjacent the first blade forms a second, different helix angle with respect to the longitudinal axis at the cutting tip. The cutting edge of the first blade is formed at a first distance with respect to the cutting edge of the second blade. A helix angle of at least one of the plurality of blades varies along the length of cut and a distance between cutting edges of the first and second blades varies along the length of cut.

A rotary cutting tool or end mill is provided, the tool comprising a plurality of pairs of diametrically-opposed, symmetrical, helical flutes formed in a cutting portion of the tool body, wherein the pitch between at least one pair of adjacent helical flutes is less than or greater than the pitch of at least one other pair of adjacent helical flutes in at least one radial plane along the axial length of the flutes, a plurality of peripheral cutting edges, wherein at least one of the peripheral cutting edges has a radial rake angle different from radial rake angle of a peripheral cutting edge of a different helical flute.