Object: To provide a cBN sintered compact having high wear resistance, and a cutting tool having high wear resistance that uses the cBN sintered compact.

Solution: A cBN sintered compact (1) including 50 vol. % or greater of cBN particles (2); and a binder phase (4) including Co; wherein in the binder phase (4), intra-phase particles (8) including Co.sub.aW.sub.b (where 0a0.95 and 0.05b1) are present. Additionally, a cutting insert (20) or similar cutting tool either includes a cBN tip (25) made from the cBN sintered compact (1) or is entirely made from the cBN sintered compact (1). The cBN sintered compact (1) and the cutting insert (20) or similar cutting tool have increased wear resistance.

Object: To provide a cBN sintered compact having high wear resistance, and a cutting tool having high wear resistance that uses the cBN sintered compact.

Solution: A cBN sintered compact (1) including 50 vol. % or greater of cBN particles (2); and a binder phase (4) including Co; wherein in the binder phase (4), intra-phase particles (8) including Co.sub.aW.sub.b (where 0a0.95 and 0.05b1) are present. Additionally, a cutting insert (20) or similar cutting tool either includes a cBN tip (25) made from the cBN sintered compact (1) or is entirely made from the cBN sintered compact (1). The cBN sintered compact (1) and the cutting insert (20) or similar cutting tool have increased wear resistance.

A cutting tool used for turning operations is releasably secured to a tool holder. The cutting insert includes top and bottom insert surfaces, each surface including two pairs of insert wedge surfaces. The tool holder includes an insert pocket having a pocket top surface and a pocket bottom surface. When the cutting tool is assembled, only one of the two pairs of insert wedge surfaces of the insert top surface engages the pocket top surface, and only one of the two pairs of insert wedge surfaces of the insert bottom surface engage the pocket bottom surface.

A cutting tool used for turning operations is releasably secured to a tool holder. The cutting insert includes top and bottom insert surfaces, each surface including two pairs of insert wedge surfaces. The tool holder includes an insert pocket having a pocket top surface and a pocket bottom surface. When the cutting tool is assembled, only one of the two pairs of insert wedge surfaces of the insert top surface engages the pocket top surface, and only one of the two pairs of insert wedge surfaces of the insert bottom surface engage the pocket bottom surface.

A cutting insert includes: a polygonal shaped upper surface; a lower surface; a side surface connected to each of the upper and lower surfaces; and an upper cutting edge located at the intersection of the upper surface and the side surface. The upper surface alternately includes three major corners and three minor corners. The upper cutting edge includes: a corner cutting edge; a minor cutting edge inclined toward the lower surface as separating from the corner cutting edge at a first inclination angle; and a major cutting edge inclined toward the lower surface as separating from the minor cutting edge at a second inclination angle. The corner cutting edge, the minor cutting edge and the major cutting edge are located sequentially from a first major corner to each of first and second minor corners, both of which are adjacent to the first major corner.

The present invention provides a cutting tool which comprises a cutting tool insert with a tip portion of cBN material having a cutting edge formed therein and a base portion forming a sintered composition with the tip portion, and a body portion coupling the cutting tool insert with a shank of the cutting tool, wherein the cutting tool insert has a rake face and a first flank face defining the cutting edge. The rake face has a negative rake angle relative to an axis parallel to a centre axis of the body portion. A second flank face defining a further edge with the first flank face is formed such that the cutting edge and the further edge do not have a common vertex. The second flank face is tilted with respect to an axis parallel to a centre axis of the body portion by an angle greater than 0.

The present invention provides a cutting tool which comprises a cutting tool insert with a tip portion of cBN material having a cutting edge formed therein and a base portion forming a sintered composition with the tip portion, and a body portion coupling the cutting tool insert with a shank of the cutting tool, wherein the cutting tool insert has a rake face and a first flank face defining the cutting edge. The rake face has a negative rake angle relative to an axis parallel to a centre axis of the body portion. A second flank face defining a further edge with the first flank face is formed such that the cutting edge and the further edge do not have a common vertex. The second flank face is tilted with respect to an axis parallel to a centre axis of the body portion by an angle greater than 0.

A composite part includes: a cutting edge part made of cubic boron nitride sintered material or WC-based cemented carbide; a cutting tool body made of cemented carbide; and a bonding part between the cutting edge part and the cutting tool body. A primarily TiC layer containing 50 area % or more of TiC is formed in an interface between the cemented carbide and the bonding part, and has a thickness of 0.5-3 m. TiNi enriched layer containing each of Ti and Ni at 30 atomic % or more is formed adjacent to the primarily TiC layer and has a thickness of 0.3-3 m. An intermittent net structure containing each of Ti, Ni and C at 10 atomic % or more is formed adjacent to the primarily TiC layer. A straight line overlapping with a major axis of each of crystal grains intersects 3 or more other crystal grains.

A composite part includes: a cutting edge part made of cubic boron nitride sintered material or WC-based cemented carbide; a cutting tool body made of cemented carbide; and a bonding part between the cutting edge part and the cutting tool body. A primarily TiC layer containing 50 area % or more of TiC is formed in an interface between the cemented carbide and the bonding part, and has a thickness of 0.5-3 m. TiNi enriched layer containing each of Ti and Ni at 30 atomic % or more is formed adjacent to the primarily TiC layer and has a thickness of 0.3-3 m. An intermittent net structure containing each of Ti, Ni and C at 10 atomic % or more is formed adjacent to the primarily TiC layer. A straight line overlapping with a major axis of each of crystal grains intersects 3 or more other crystal grains.

A cutting insert includes: a polygonal shaped upper surface; a lower surface; a side surface connected to each of the upper and lower surfaces; and an upper cutting edge located at the intersection of the upper surface and the side surface. The upper surface alternately includes three major corners and three minor corners. The upper cutting edge includes: a corner cutting edge; a minor cutting edge inclined toward the lower surface as separating from the corner cutting edge at a first inclination angle; and a major cutting edge inclined toward the lower surface as separating from the minor cutting edge at a second inclination angle. The corner cutting edge, the minor cutting edge and the major cutting edge are located sequentially from a first major corner to each of first and second minor corners, both of which are adjacent to the first major corner.