A milling tool is suggested having a base body (3), a central axis (M), and a front side (5), whereby at least two geometrically defined first front edges (9) that are arranged, respectively, at front side (5) of base body (3) exhibit a first edge section (13) facing central axis (M). Milling tool (1) distinguishes itself by the first edge sections (13) of the at least two front edges (9) being formed in an ascending fashion towards center axis (M), so that they form a centering tip (15), and that centering tip (15) is arranged in a recessed manner in an axial direction when compared with an axial outermost point (17) of at least two of the first front edges (9) (FIG. 1).

A single-sided four-way indexable cutting insert includes a positive basic shape, a rake surface, a peripheral surface including four side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has an imaginary square frustum which defines a square base containing the cutting insert's base bearing surface, and further defines four isosceles trapezoid side surfaces respectively containing the cutting insert's four side abutment surfaces. A material volume V.sub.F of the cutting insert and a void volume V.sub.S of the insert fulfill the condition V.sub.S/V.sub.F0.25.

An orbital drill includes a drilling portion, a shank portion, and a neck portion between the drilling portion and the shank portion. The drilling portion includes one or more right-handed spiral flutes with cutting edges having a positive axial rake angle for positive cutting action while orbiting into a material. The right-handed spiral flutes have a positive radial and axial rake angle. The drilling portion also includes one or more left-handed spiral flutes located rearward of the one or more right-handed spiral flutes with cutting edges having a positive axial and radial rake angle for positive cutting action while orbiting back out of the material and removing any material left in the hole, thereby eliminating a separate reaming operation. A method of machining a workpiece using the orbital drill is also disclosed.

A reusing method of an end mill involves machining a base material of an end mill in advance so as to have coaxiality equal accuracy to coaxiality for a cutting part, and when the cutting part is worn out, cutting off of the cutting part and machining a new cutting part on a shank part while a part of outer peripheral surface of the shank part is left as margin without cutting. The new cutting part has accuracy of coaxiality and an outer diameter identical to those of the cutting part.

An orbital drill includes a drilling portion, a shank portion, and a neck portion between the drilling portion and the shank portion. The drilling portion includes one or more right-handed spiral flutes with cutting edges having a positive axial rake angle for positive cutting action while orbiting into a material. The right-handed spiral flutes have a positive radial and axial rake angle. The drilling portion also includes one or more left-handed spiral flutes located rearward of the one or more right-handed spiral flutes with cutting edges having a positive axial and radial rake angle for positive cutting action while orbiting back out of the material and removing any material left in the hole, thereby eliminating a separate reaming operation. A method of machining a workpiece using the orbital drill is also disclosed.

An indexable cutting insert has opposing upper and lower end surfaces, and a peripheral surface including three side surfaces circumferentially alternating with three corner surfaces. The three side surfaces define an imaginary triangle and an imaginary hexagon. Each corner surface intersects the upper end surface to form an upper corner peripheral edge having a primary cutting edge. In a top view, each triangle side traverses two upper corner peripheral edges, imaginary lines tangential to the end points of each primary cutting edge are either collinear or form an obtuse angle greater than 175 degrees, each primary cutting edge has a primary length greater than half the hexagon side length, and at least one triangle side traverses each primary cutting edge. The insert is removably secured in a rotary cutting tool such that one of the upper corner peripheral edges contains an axially forwardmost point of the insert's upper peripheral edge.

A mirror finishing method for mirror-finishing a workpiece includes: a step of performing a first machining operation with a first tool which has a cylindrical portion made of polycrystalline diamond or cubic boron nitride at the tip of a shank thereof and further has a cutting edge formed by forming a linear groove on the cylindrical portion; and a step of, after the first machining operation has been performed, performing a second machining operation with a second tool which has a cylindrical portion made of polycrystalline diamond or cubic boron nitride at the tip of a shank thereof with no cutting edge on the cylindrical portion.

The present invention provides a cutting insert in which suitable honing is formed on a cutting edge. The cutting insert is provided with: two end surfaces opposing each other; a peripheral side surface extending between the two end surfaces; and a cutting edge formed on an intersecting ridge between at least one of the two end surfaces and the peripheral side surface. The cutting edge at least includes a major cutting edge and an inner cutting edge. Honing is provided on the major cutting edge and the inner cutting edge. A width of second honing of the inner cutting edge is narrower than a width of first honing of the major cutting edge, as viewed from a side of the end surfaces.

A micro form end mill includes a tool shank (2) and a cutting head (3) fixedly connected to the tool shank (2). The cutting head (3) has a plurality of cutting teeth (Z), and each of the plurality of cutting teeth (Z) has a cutting edge (S). A maximum radial distance (A.sub.max) of cutting points (6, 7, 8, 9) on the cutting edge (S) from the longitudinal axis (L) is less than 0.5 mm. At least two of the cutting edges (S) are arranged with a radial offset (V) from one another at least regionally. The radial offset (V) corresponds to a difference in the radial distances from the longitudinal axis (L) of such cutting points (6, 7, 8, 9) to the at least two cutting edges (S) that lie in a common plane (E) that is perpendicular to the longitudinal axis (L).

In the ball end mill, at least two end cutting edges are extended to the vicinity of an axis at a tip portion of an end mill main body which rotates around the axis. In two gashes in which two end cutting edges adjacent to each other in a circumferential direction are formed, a first gash on the end mill rotation direction side extends beyond the axis on the tip of the end mill main body and a second gash on the rear side in the end mill rotation direction does not exceed the axis. A first tip flank face which intersects with the first gash through a first end cutting edge is extended toward a second tip flank face which intersects with the second gash through a second end cutting edge.