A cutting insert (10) for a tool (100) for machining a workpiece. The cutting insert (10) is a four-bladed cutting insert which is in the form substantially of a rhomboid. The cutting insert (10) has two identical, oppositely arranged base sides (14a, 14b) and four identical main sides (16a-16d) which extend between the two base sides (14a, 14b). Each of the four main sides (16a-16d) comprises a rectilinear main cutting edge (12a-12d) and a rectilinear secondary cutting edge (26a-26d) which is arranged transversely thereto. The main and secondary cutting edges (12a-12d) and (26a-26d) of each main side (16a-16d) lie in each case in a common cutting plane which is aligned parallel to a contact surface (28a-28d) which is also provided on the main sides (16a-16d).

In an end mill body made of ceramic, a corner R rake face is formed in such a manner as to contain a point B and at least a region B, not a region A located on a side toward an end cutting edge. In other words, a first end portion of a cutting edge on a peripheral edge portion of the corner R rake face is formed on a peripheral edge of the region B of a corner R cutting edge, and a second end portion of the cutting edge reaches at least the point B. As a result, partial breakage of the corner R cutting edge is unlikely to occur in the course of cutting. That is, since the corner R rake face is formed in such a manner as to start from the first end portion located apart from a point A, which is the intersection of the end cutting edge and the corner R cutting edge, and such that the second end portion reaches the point B, a large cutting load is unlikely to be imposed on the starting point of the corner R rake face. Therefore, the corner R cutting edge is unlikely to be chipped.

In one aspect, elongated rotary cutting tools such as end mills are described herein which may provide one or more advantages over prior designs. For example, in some embodiments, cutting tools described herein can provide reduced wear rates at corner cutting edges, may permit high ramp angles during processing up to and including 45 ramp angles, and/or increased tool life.

A single-edged milling tool has a shaft section and a machining section. A face cutting edge is formed on a distal end of the machining section. The face cutting edge extends radially from an outside end at an outer peripheral edge to an inside end close to the axis of rotation. The face cutting edge has an outer peripheral planar portion at a constant planar distance to a reference plane extending perpendicular to the axis of rotation. An oblique portion connects the planar portion to the inside end. The oblique portion of the face cutting edge is closer to the reference plane than the planar portion. The distance of the face cutting edge from the reference plane in the oblique portion diminishes continuously starting out from the planar portion to the inside end of the face cutting edge.

An end mill configured as a high feed circle segment cutter and a high feed end cutter utilizable in 5-Axis machining. The end mill comprises the end work of a high feed mill and the fluting of a circle segment cutter, thereby allowing the operator to rough out the bulk of the material with a high feed method (small axial and larger radial depths of cuts), then use the side of the tool to finish/semi-finish the walls of the part with the circle segment cutter geometry on the side of the tool.

An indexable rotary cutting tool comprising, a twist angle of the outer peripheral cutting edge having a positive value, an axial rake angle of the cutting edge of the corner R at a boundary point between the cutting edge of the corner R and the outer peripheral cutting edge has a positive value, the axial rake angle of the cutting edge of the corner R at the reference point has a negative value, at least the radial rake angle in a region between the boundary point and the reference point in an entire edge length region of the cutting edge of the corner R has a negative value, and the radial rake angle of the cutting edge of the corner R at the reference point is smaller than the radial rake angle of the cutting edge of the corner at the boundary point.