A ball end mill according to the present invention includes an end mill body which is formed in a shaft shape, a plurality of convex arcuate end cutting edges which are disposed on a tip portion of the end mill body at intervals around an axis and form a hemispherical shape such that a rotational locus around the axis has a center on the axis, and a plurality of gashes which are respectively disposed to be adjacent to the plurality of end cutting edges in an end mill rotation direction around the axis. The plurality of end cutting edges includes a first end cutting edge longest among the plurality of end cutting edges, a second end cutting edge which is adjacent to the first end cutting edge in the end mill rotation direction and a third end cutting edge which is adjacent to the second end cutting edge in the end mill rotation direction.

A rotary cutting tool having an axis of rotation, a shank area, and a cutting area. The rotary tool has chip flutes reaching as far as a core profile in the cutting area. In order to reduce vibrations of the rotary cutting tool and therefore to permit precise machining and high surface quality with long service lives, the center line of the core profile has a course that deviates from the axis of rotation of the rotary cutting tool and/or the core profile contains mutually alternating sections with increasing cross-sectional area and sections with decreasing cross-sectional area over the length of the cutting area.

An end mill includes end cutting edges located at a front end side of a cutting edge portion of a body including rotation axis, peripheral cutting edges, and helically extending flutes. Each of the peripheral cutting edges and the flutes are alternately located from the front end side to a rear end side, and a first distance between a deepest position of the flute and the rotation axis is equal among the respective flutes in a cross section taken along the rotation axis. The flute includes a first region located at a side of the peripheral cutting edge and includes the deepest position, a second region located at a side of a heel, and a boundary. A second distance from the rotation axis to the boundary located at the rear end side is larger than the second distance located at the front end side.

An end mill includes an end mill body having a bar-shape extending along a rotation axis and including a first end and a second end, a side surface, a first end cutting edge, a second end cutting edge, a first peripheral cutting edge extending from the first end cutting edge, and a second peripheral cutting edge extending from the second end cutting edge. In which, L2 is smaller than L1, where L1 is a distance from the rotation axis to the first peripheral cutting edge, and L2 is a distance from the rotation axis to the second peripheral cutting edge in a cross section orthogonal to the rotation axis. And 2 is greater than 1, where 1 is a rake angle of the first peripheral cutting edge, and 2 is a rake angle of the second peripheral cutting edge.

An end mill has a shank section and a cutting section connected thereto. The cutting section includes a core supporting at least two spaced apart teeth that have a cutting edge extending in the axial direction with respect to the axis of rotation of the end mill. Each cutting edge has a flute associated therewith and each flute has, for each cross-section of the end mill perpendicular to the axis of rotation thereof, a bottom point on the core at a shortest distance to the axis of rotation. At least two flutes have a shortest distance that varies differently with the distance to a cutting end of the end mill.

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 rotary cutting tool having an axis of rotation, a shank area, and a cutting area. The rotary tool has chip flutes reaching as far as a core profile in the cutting area. In order to reduce vibrations of the rotary cutting tool and therefore to permit precise machining and high surface quality with long service lives, the center line of the core profile has a course that deviates from the axis of rotation of the rotary cutting tool and/or the core profile contains mutually alternating sections with increasing cross-sectional area and sections with decreasing cross-sectional area over the length of the cutting area.