The present invention includes an end mill body which is formed of ceramic, a chip discharge flute which is formed on an outer periphery of the end mill body, a peripheral cutting edge which is formed on an intersection ridge line between a wall surface facing a tool rotation direction in the chip discharge flute and an outer peripheral surface of the end mill body, an end cutting edge which is formed on an intersection ridge line between the wall surface in the chip discharge flute and a tip surface of the end mill body, and a corner cutting edge which is positioned at a tip outer-peripheral part of the end mill body, connects an outer end of the end cutting edge and a tip of the peripheral cutting edge to each other, and has a convexly curved shape which is convex toward a tip outer-peripheral side of the end mill body.

A corner radius end mill includes a blended gash extending along a cutting edge. The blended gash is formed in a corner sector of the end mill. The corner sector has a first half-sector and a second half-sector defined on opposite sides of an imaginary bisection line of the corner sector, the first and second half-sectors subtending equal angles about the imaginary bisection line. The blended gash extends from a first extremity and blends an end gash surface and flute rake surface of the corner radius end mill. The blended gash is spaced from a radial tangent point by a predetermined distance, and extends to a second extremity which is spaced apart from the axial line and the second half-sector.

The invention relates to a side milling cutter (1) which comprises a disk body (11) with a central hub (12) for accommodation in a milling drive, and a plurality of cutters (21) which are arranged on the outer periphery thereof. A plurality of inner cooling lubricant channels (3) extend in the disk body (11), said channels having two or more outlet openings (31) in the area of each cutter (21). Said outlet openings (31) are oriented such that a cooling lubricant jet (K) which exits from the cooling lubricant channel (3) can be directed to the cutter (21). The invention also relates to a production method for the side milling cutter (1).

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).

A cutting tool, including a silicon nitride (Si.sub.3N.sub.4) ceramic substrate, and a diamond film coated on the surface of the Si.sub.3N.sub.4 ceramic substrate. The diamond film has a thickness of 7-12 μm. The cutting tool includes a tool nose, a blade, and a handle. The blade has a rake angle γ of 5-15°, a clearance angle α of 10-14°, and a helix angle of 15-45°. The blade includes four cutting edges.

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.

A radius endmill suppressing chatter vibration includes a circular arc edge provided on an outer peripheral side of a distal end portion of a tool body, and a nose (R) angle (r) that is an angular range in which the circular arc edge is formed in a vertical section including a central axis line of the tool body and which is equal to or less than 30. The circular arc edge is formed, as a circular arc edge for a bottom surface, from a position having a tangential line in a direction that perpendicularly intersects the central axis line to a side surface in a bottom surface of the distal end portion of the tool body in a vertical section. A nose (R) height (Hr) that is a dimension of the circular arc edge in the direction of the central axis line is equal to or less than 0.75 mm.

In an indexable rotary cutting tool of the present invention, a cutting edge portion of an insert includes a peripheral cutting edge, a bottom cutting edge, a cutting edge of a corner R, and a chamfered surface, a radial rake angle () of the cutting edge of the corner R has a negative value in an entire edge length region of the cutting edge of the corner R, and the radial rake angle () becomes a minimum value at an intermediate portion located between a pair of boundary points (P, Q) in the cutting edge of the corner R.

In an indexable rotary cutting tool of the present invention, a cutting edge portion of an insert includes a peripheral cutting edge, a bottom cutting edge, a cutting edge of a corner R, and a chamfered surface, a radial rake angle () of the cutting edge of the corner R has a negative value in an entire edge length region of the cutting edge of the corner R, and the radial rake angle () becomes a minimum value at an intermediate portion located between a pair of boundary points (P, Q) in the cutting edge of the corner R.

An indexable rotary cutting tool and insert is capable of performing a high-accuracy cutting process with high efficiency. A twist angle of an outer peripheral cutting edge of the tool has a positive value, an axial rake angle of the cutting edge of a corner R of the tool 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 a reference point has a negative value, and the radial rake angle at least 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. The radial rake angle at the reference point is smaller than the radial rake angle at the boundary point.