A cutting tool assembly includes: a cutter body extending perpendicularly from a bottom surface and including a cylindrical portion with a rotational axis; insert pockets disposed and formed concavely in the bottom surface and the cylindrical portion to be spaced apart from each other along a circumferential direction; fixed cutting inserts mounted within the insert pockets and disposed at the outermost portion of the cutter body in a radial direction; and stepped cutting inserts mounted within the insert pockets, the stepped cutting insert being disposed between two adjacent fixed cutting inserts. The fixed cutting insert is disposed to have an identical length from the rotational axis and an identical length from the bottom surface. At least one stepped cutting insert is disposed to have a different length from the rotational axis and a different length from the bottom surface compared to the remaining stepped cutting inserts.

A cutting insert has opposing first and second end surfaces, and a peripheral side surface (connecting the end surfaces. A central axis penetrates the two end surfaces. The peripheral sure surface includes an outwardly inclined first side surface part related to a major cutting edge and a second side surface part related to a minor cutting edge. The outwardly inclined first side surface part gradually extends outward from the cutting insert, heading from the first end surface to the second end surface. When a second virtual plane, which is substantially perpendicular to the central axis and passes through the major cutting edge, is defined, an inwardly inclined part, on a back side of the cutting edge, of the second end surface is inclined so as to become more distant from the second virtual plane, heading from the outwardly inclined first side surface part to the central axis.

A cutting insert has opposing first and second end surfaces, and a peripheral side surface (connecting the end surfaces. A central axis penetrates the two end surfaces. The peripheral sure surface includes an outwardly inclined first side surface part related to a major cutting edge and a second side surface part related to a minor cutting edge. The outwardly inclined first side surface part gradually extends outward from the cutting insert, heading from the first end surface to the second end surface. When a second virtual plane, which is substantially perpendicular to the central axis and passes through the major cutting edge, is defined, an inwardly inclined part, on a back side of the cutting edge, of the second end surface is inclined so as to become more distant from the second virtual plane, heading from the outwardly inclined first side surface part to the central axis.

A cutting insert includes a cutting edge having an involute-curve approximate shape. A cutting edge is formed so as to wholly take on a first curved shape with a first curvature radius when the cutting insert is viewed from the end surface, and is formed so that a large part of the cutting edge takes on a second curved shape with a second curvature radius when the cutting insert is viewed from the side surface.

A prismatic and cylindrical cutting insert for long edge rotary milling applications has multiple indexable cutting edges ranging from four to six or even more depending on the actual milling applications. Each cutting edge of a prismatic or cylindrical cutting insert provides a positive cutting geometry and is equivalent to an indexable cutting edge of a traditional single-sided parallelogram-shaped cutting insert having two indexable cutting edges (often referred as A-Style insert). The prismatic and cylindrical (including tapered or conical) cutting insert may be used for machining a wide range of materials including difficult-to-machine materials, cast-iron and alloys, aluminum and alloys, carbon steels, and fiber reinforced composites.

A prismatic and cylindrical cutting insert for long edge rotary milling applications has multiple indexable cutting edges ranging from four to six or even more depending on the actual milling applications. Each cutting edge of a prismatic or cylindrical cutting insert provides a positive cutting geometry and is equivalent to an indexable cutting edge of a traditional single-sided parallelogram-shaped cutting insert having two indexable cutting edges (often referred as A-Style insert). The prismatic and cylindrical (including tapered or conical) cutting insert may be used for machining a wide range of materials including difficult-to-machine materials, cast-iron and alloys, aluminum and alloys, carbon steels, and fiber reinforced composites.

A cutting insert includes an end cutting edge, a first major cutting edge, and a second major cutting edge. The height of the end cutting edge relative to an imaginary plane orthogonal to a central axis of a through-hole is fixed. The height of the first major cutting edge relative to the imaginary plane increases, when viewed from a side, moving away from the end cutting edge. The height of the second major cutting edge relative to the imaginary plane decreases, when viewed from a side, moving away from the first major cutting edge. When viewed from a side, the angle of inclination, relative to the imaginary plane, of an imaginary line connecting both ends of the second major cutting edge is greater than an angle of inclination, relative to the imaginary plane, of an imaginary line connecting both ends of the first major cutting edge.

A cutting insert of an embodiment includes an upper surface including a first upper cutting edge and a second upper cutting edge, a lower surface including a first lower cutting edge and a second lower cutting edge, and a side surface. The side surface includes a first surface extending from the second upper cutting edge, a second surface extending from the first lower cutting edge, a third surface extending from the first upper cutting edge, and a fourth surface extending from the second lower cutting edge. The first surface and the fourth surface are parallel to a central axis. The second surface is inclined so as to depart from the central axis as going from the lower surface toward the upper surface. The third surface is inclined so as to depart from the central axis as going from the upper surface toward the lower surface.

The invention concerns a cutting insert comprising an upper and a lower surface and one or more edge surfaces which connect the upper surface and the lower surface together, wherein provided at the transition of at least one edge surface at least to the upper surface is at least one cutting edge, wherein the upper surface adjoining the cutting edge is in the form of a chip surface and the edge surface adjoining the cutting edge is in the form of a tool flank. To provide a cutting insert in which the chip break range is enlarged and the risk of damage to the cutting insert and/or the tool and/or the workpiece by coiling chips is reduced it is provided according to the invention that at least one recess is provided in the tool flank at a spacing from the cutting edge.

An insert includes a rake angle set corresponding to the hardness of a material to be cut and that can suppress an increase in the material cost even when the strength of a cut edge section is increased. The insert has a polygonal shape and includes a cutting edge portion on at least one side of the polygonal shape. The cutting edge portion includes a rake face having a convex formed on one of opposite surfaces in the thickness direction a flank face having a concave formed on a surface intersecting with the one surface in the thickness direction and a concave cutting edge that is formed between the rake face and the flank face.