Chip discharge during high-feed machining and low-feed machining particularly in a high-depth-of-cut state or the like is improved so as to provide adaptability to a wide range of cutting conditions during low depth and high depth cutting and during low-feed and high-feed machining and allow so-called freedom of feed during cutting to be improved. A cutting insert includes a cutting edge body and a substrate to which the cutting edge body is joined. The cutting edge body has a prismatic shape having a longitudinal direction and a lateral direction perpendicular to the longitudinal direction and includes a cutting edge formed on an intersecting edge between a peripheral side surface and an upper surface of the cutting edge body having the prismatic shape and a recessed part formed at a position on the upper surface of the cutting edge body which is more distant from the intersecting edge than from the cutting edge. The substrate has a projected part upwardly projecting from the upper surface of the cutting edge body.

Chip discharge during high-feed machining and low-feed machining particularly in a high-depth-of-cut state or the like is improved so as to allow so-called freedom of feed during cutting to be improved. A cutting edge body of a cutting insert includes a front cutting edge formed on one end side in a longitudinal direction, the front cutting edge being a cutting edge formed on an intersecting edge between a peripheral side surface and an upper surface of the cutting edge body having a prismatic shape, a side cutting edge formed on one end side in a lateral direction, a recessed part provided in the upper surface of the cutting edge body to be subsequent to the side cutting edge in the lateral direction, and a wall part having a wavy wall surface formed in a portion of the recessed part and a discrete wall surface formed at a position between the wavy wall surface and the side cutting edge and including a plurality of surfaces which are discrete along the longitudinal direction.

A cutting blade having a plurality of different coatings on surfaces thereof, including an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface, wherein the upper surface intersects the side surface to form at least one cutting edge unit, the cutting edge unit includes a main cutting edge and a secondary cutting edge, the upper surface includes at least one set of cutting planes, the cutting planes include a main cutting surface and a secondary cutting surface, the main cutting surface intersects the side surface to form the main cutting edge, the secondary cutting surface intersects the side surface to form the secondary cutting edge, a main coating is provided on the main cutting surface, a secondary coating is provided on the secondary cutting surface, and the main coating and the secondary coating are independent from each other.

A turning insert includes a top surface, an opposite bottom surface, a side surface connecting the top and bottom surfaces, and a cutting edge formed at an intersection between the top surface and the side surface. The cutting edge including a corner cutting edge, a first cutting edge, and a second cutting edge. The top surface having a first surface in the form of a depression, which borders at least a major portion of the corner cutting edge. The first and the second cutting edges subtending an angle θ which is 75-85°. At least a part of the corner cutting edge is concave in a front view.

An insert may include a base member and a resin layer located on the base member. The base member may include a first surface, a second surface, and a cutting edge. The first surface includes a rake surface region. The second surface may be adjacent to the first surface and includes a flank surface region. The cutting edge may be located in at least a part of a ridge line at which the first surface intersects with the second surface. The resin layer may not be located on the second surface but may be located on the first surface.

In accordance with various illustrative embodiments of the present disclosure, a rotationally symmetric surface of a workpiece is machined by a turning apparatus, wherein the workpiece is rotationally driven around a rotational axis, a cutting tool with a cutting edge positioned at the edge of a rake face is arranged relative to the workpiece, the cutting tool is brought into contact with the workpiece, and the cutting tool is advanced relative to the workpiece along a feed direction parallel to the rotational axis, the normal to the rake face being tilted relative to the feed direction, a first axis and a second axis, the first axis and the second axis are perpendicular to the feed direction and perpendicular to each other.

When seen in a direction perpendicular to a seating surface, the second boundary line has a first portion and a second portion, the first portion having an inclination relative to the second cutting edge portion in a counter clockwise direction, the first portion being located between the first boundary line and an intersection between the second boundary line and a straight line passing through a center of a mounting hole and perpendicular to the second cutting edge portion, the second portion being located opposite to the first portion relative to the intersection, the second portion having an inclination relative to the second cutting edge portion in a clockwise direction.

A cutting insert has a seating surface, an outer peripheral surface, a top surface, and an attachment hole. The cutting edge includes a curved cutting corner edge portion, a first cutting edge portion, and a second cutting edge portion. The top surface includes a first rake face contiguous to the first cutting edge portion, a second rake face contiguous to the second cutting edge portion, and a third rake face contiguous to the cutting corner edge portion and also contiguous to the first and second rake faces. The third rake face has a first region contiguous to the first rake face and a second region contiguous to the second rake face. The first rake face and the first region each have a rake angle which is a positive angle. The second rake face and the second region each have a rake angle which is a negative angle.

A cutting tool comprises a substrate and a coating that coats the substrate, the coating including an -alumina layer, the -alumina layer including crystal grains of -alumina, the -alumina layer including a lower portion and an upper portion, the upper portion being occupied in area at a ratio of 50% or more by crystal grains of -alumina having (006) plane with a normal thereto having a direction within 15 with respect to a direction of a normal to the second interface, the lower portion being occupied in area at a ratio of 5% or more and less than 50% by crystal grains of -alumina having (012) plane, (104) plane, (110) plane, (113) plane, (116) plane, (300) plane, (214) plane and (006) plane each with a normal thereto having a direction within 15 with respect to the direction of the normal to the second interface.

A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.