A replaceable milling head rotatable in a cutting direction about a longitudinal central axis, the central axis defining a forward direction and an opposite rearward direction, has a forward cutting portion and a rear threaded coupling portion for coupling to a shank. The cutting portion includes two or more key actuating portions which assist in mounting the milling head onto the shank. The cutting portion includes a plurality of helical chip flutes alternating with cutting edges. At least one or more of the cutting edges and flutes extend axially rearward of at least a portion of the key actuating portions.

A cutter head structure includes a cutting edge portion including a cutting body. An outer surface of the cutting body is a curved surface which protrudes forwardly. The outer surface of the cutting body is provided with a first cutting edge and at least two second cutting edges. The first cutting edge extends from one side of the cutting body to a top region of the cutting body and then to the other side of the cutting body. The second cutting edges are respectively disposed on both sides of the first cutting edge. First chip flutes are defined between the first cutting edge and the second cutting edges adjacent thereto, and each of the first chip flutes has a width gradually increasing from the top region to both ends of the cutting body.

The purpose of the present invention is to perform machining on a double-curved surface to have good finished surface characteristics while achieving high speed feeding. An end mill (2) is provided with a bottom blade (2A) formed in a curved convex and circular arc shape, and a radius blade (2B) located at the edge and formed in a circular arc shape. The bottom blade (2A) has a region where a blade part is not formed on the axis of the end mill (2), and the end mill (2) is further provided with a center blade (2C) in the region of the bottom blade (2A). The center blade (2C) is formed in a circular arc shape with a radius smaller than that of the circular arc part of the bottom blade (2A).

Provided is an end mill which includes an end mill main body having a bottom blade having a convex hemispherical shape, and a hard coating film coated on at least a surface of a distal end portion of the end mill main body. A diameter D (mm) of the bottom blade is 2 mm or less. A ratio W/D of a width W (mm) of a chisel portion to the diameter D (mm) is within a range of 0.020 to 0.060. A ratio L/D of a facing length L (mm) of chip discharge grooves to the diameter D (mm) is within a range of 0.014 to 0.090. A rake angle of the bottom blade in a range in which a chisel edge is formed in the chisel portion is within a range of −15° to −30°.

An insert includes a main body extending from a first end toward a second end. The main body includes a cutting edge, a rake face, and a flute. In the rake face, a second rake angle of a second surface region positioned closer to the second end than a first surface region connected to the cutting edge is smaller than a first rake angle of the first surface region. A third rake angle of a third surface region is smaller than the second rake angle, the third surface region being adjacent to the flute rearward in a rotational direction and on an outer peripheral side of the main body.

An end mill for milling composite materials, for example, fiber-reinforced plastics, having a defined rotating direction, a shank and a cutting part that extends from a shank-side end up to a frontal end and in a front length region adjoining the frontal end of the cutting part, has a plurality of first circumferential cutters running with a positive helix angle, each of which adjoins a first groove running with a positive helix angle, and in a rear length region adjoining the shank-side end of the cutting part, has a plurality of second circumferential cutters running with a negative helix angle, each of which adjoins a second groove running with a negative helix angle. At least a part of the first circumferential cutters in the front length region, and at least a part of the second circumferential cutters in the rear length region, are each divided into cutting segments.

A replaceable milling head rotatable in a cutting direction about a longitudinal central axis, the central axis defining a forward direction and an opposite rearward direction, has a forward cutting portion and a rear threaded coupling portion for coupling to a shank. The cutting portion includes two or more key actuating portions which assist in mounting the milling head onto the shank. The cutting portion includes a plurality of helical chip flutes alternating with cutting edges. At least one or more of the cutting edges and flutes extend axially rearward of at least a portion of the key actuating portions.

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.

The present invention is to eliminate formation of a shape that induces reduction of fatigue strength, without forming a step part, in a shape portion formed by machining. This processing apparatus includes end mills having bottom blades formed in a curved convex shape, and arcuately formed radial blades provided in corner areas; a drive section for driving the end mills; and a control unit for controlling the drive unit. The control unit includes a planar-shape-formation unit that controls the drive unit so as to form, in a workpiece, only a planar-shape portion adjacent to a fillet shape portion in such a manner that a portion of the shape to be processed corresponding to the fillet shape portion is left unprocessed; and a fillet formation unit that controls the drive unit so as to form the fillet shape portion in the workpiece in a single pass using the radial blades.

A metal slitter body including a cylindrical body portion and cutting body portions extending outwardly from and integrally formed with the cylindrical body portion. The cutting body portions each include an insert pocket having an insert receiving slot, first and second clamping jaws and a slot end. The slitter body further including a reinforcement portion extending from the cylindrical body in an outward radial direction further than each slot end.