The current invention proposes sharpening thin hardened metal blades with the hard turning process using a holder designed to hold the blades in a firm and stiff manner and a ceramic cutting tool held in a fixture. Generally, the cutting tool is held stationary in its fixture while the workpiece, in its holder, is rotated such that it repeatedly comes into controlled contact with the cutting tool. In sharpening operations such as proposed here, it is critical to (i) hold the workpiece firmly and rigidly, and (ii) position the cutting tool in a precise, predictable and reliable manner.

An assembly-type cutter includes a shank and a cutter head. The shank has a hole at one end. The hole has a receiving portion, which includes an internal thread and can be treated thermally for increased rigidity. The cutter head has a cutting portion and a connecting portion at opposite ends respectively. The connecting portion includes a threaded member and can also be treated thermally for increased rigidity. The cutter head and the shank are threadedly connectable via the connecting portion and the receiving portion. The threaded member includes a body portion, whose diameter is defined as a root diameter, and an external thread on the body portion. The body portion is slightly tapered such that a locus of the root diameter is inclined.

Provided is a tip dresser blade comprising a body of M-2 steel hardened to a Rockwell C hardness in the range of 63 to 66, inclusive, by double tempering. The body may be ground to provide a specific first geometry, or a specific second geometry, or a specific third geometry, or a specific fourth geometry.

Provided is a tip dresser blade blank comprising a casting of M-2 steel hardened to a Rockwell C hardness in the range of 63 to 66, inclusive, by double tempering. The casting may be ground to provide a specific first geometry or a specific second geometry.

Provided is a method of machining a sealing surface, the method being capable of finishing a sealing surface at low cost and in a short period of time, eliminating lead marks, and forming the sealing surface highly accurately. The method of machining a sealing surface comprises finishing a sealing surface (M), which is to be machined, by cutting the sealing surface (M) using a rotating cutting tool (81) while rotating a workpiece having the sealing surface (M) about an axis thereof. The cutting of the sealing surface (M) using the rotating cutting tool (81) comprises hardened steel cutting which generates no lead marks.

Ceramic end mill with cutting edge portion including gashes between cutting edges and adjacent in a rotation direction. Center cut edges are formed at end cutting edges close to and facing rotation axis O. Center grooves are formed on rear sides of center cut edges and end cutting edges in the rotation direction continuous with a radial direction. The center grooves are continuous with positions where end cutting edge second surfaces face or approach rotation axis O. End cutting edge second surfaces are laid between center cut edges and end cutting edges. Center grooves are formed between end cutting edge second surfaces and center cut edges positioned on a rear side of end cutting edge second surfaces in the rotation direction. The center grooves pass on rotation axis O. Center grooves double as rake faces of the respective center cut edges and are continuous with the gashes.

A surface-coated cutting tool of the present invention includes: a hard coating layer which is vapor-deposited on a surface of a tool body made of tungsten carbide-based cemented carbide and has an average thickness of 2 mm to 10 mm, in which (a) the hard coating layer comprises a layer made of complex nitride of Al, Cr, and B in which a ratio (atomic ratio) of the amount of Cr is 0.2 to 0.45 and a ratio (atomic ratio) of the amount of B is 0.01 to 0.1 to the total amount of Al, Cr, and B, and (b) in an area within 100 mm from an edge tip on a flank face of the surface-coated cutting tool, the hard coating layer has a granular crystal grain structure and the average grain size of granular crystal grains is 0.1 mm to 0.4 mm on the surface of the hard coating layer.

A rotary tool for machining workpieces, comprising at least one main body with a clamping segment, a tool head comprising a cutting region, and at least one coolant channel for feeding a cooling and lubricating fluid into the cutting region. At least one partial surface section of the cutting region forms a hardened region, which covers and/or defines the coolant channel and is surface-hardened. A method for producing a rotary tool.

An assembly-type cutter includes a shank and a cutter head. The shank has a hole at one end. The hole has a receiving portion, which includes an internal thread and can be treated thermally for increased rigidity. The cutter head has a cutting portion and a connecting portion at opposite ends respectively. The connecting portion includes a threaded member and can also be treated thermally for increased rigidity. The cutter head and the shank are threadedly connectable via the connecting portion and the receiving portion. The threaded member includes a body portion, whose diameter is defined as a root diameter, and an external thread on the body portion. The body portion is slightly tapered such that a locus of the root diameter is inclined.