Abstract: A cutting tool is provided which comprises a curved cutting edge at a nose, a pair of straight cutting edges between which the nose is located, and a chamfer extending along the curved cutting edge and the straight cutting edges so as to form a curved ridge at a junction of a portion of the chamfer extending along the curved cutting edge and a tool face. A portion of the chamfer increases in width from a junction of the curved cutting edge and each of the straight cutting edges to a midpoint of the curved cutting edge when observed in plan.

Abstract: A tip having an arcuate cutting edge capable of enhancing chip disposal. A ridgeline 4a of an arcuate cutting edge 4 and a rake face 7a extending rearward therefrom assume the form of a concave arc as viewed from the side of a front flank 8. Through radial feed of the tip 1, a raceway groove having an arcuate cross section is cut. The cross section of an ejected chip is deformed into an arcuate form according to the concave form of the ridgeline 4a and the rake face 7a. Thus, the rigidity of the chip is enhanced and is less likely to weave about. The chip is ejected straight rearwardly along the rake face 7a, and is curled into a spiral form on the rake face 7a, thereby improving chip disposal.

Abstract: A cutting tool is provided which comprises a curved cutting edge at a nose, a pair of straight cutting edges between which the nose is located, and a chamfer extending along the curved cutting edge and the straight cutting edges so as to form a curved ridge at a junction of a portion of the chamfer extending along the curved cutting edge and a tool face. A portion of the chamfer increases in width from a junction of the curved cutting edge and each of the straight cutting edges to a midpoint of the curved cutting edge when observed in plan.

Abstract: A plunge-cutting forming tip which improves chip disposal. A protrusion (11) is disposed on a rake face (7) in the vicinity of the ridgeline of a plunge-cutting edge (3). In cutting by means of the tip (1), a chip (K) is ejected which is not only merely thin, but also is ejected in such a manner as to be partially squeezed as a result of pressing against the protrusion (11). Accordingly, the chip is ejected such that a cross section thereof is deformed into a channel shape instead of assuming a flat shape. Thus, the rigidity of the chip is increased, so that chip disposal is improved accordingly.

Abstract: Heat- and wear-resistant ceramic materials is produced by sintering a composition until Ti cannot be detected as the metallic phase, said composition comprised of 5 to 40% by weight of Al.sub.2 O.sub.3, 0.05 to 4% by weight of a sintering aid and 56 to 94.95% by weight of a TiC component in which 4 to 30% by weight of TiC are substituted with Ti.