The technical objective of the present invention is to provide a cutting insert that can minimize a phenomenon in which the cutting insert is lifted up from a seat surface of a cutting tool while a cutting process is being performed, and can increase an area by which the cutting insert is fastened to the cutting tool. To this end, the cutting insert of the present invention comprises: a principal surface; a fastening surface opposite to the principal surface, the fastening surface being placed on the seat surface of the cutting tool; and a screw passage hole formed through each of central portions of the principal and fastening surfaces, wherein a screw is fastened to the cutting tool through the screw passage hole; and first and second long grooves extending across the fastening surface, wherein each of the first and second long grooves includes: a proximal sidewall adjoining a first adjacent fastening portion of the fastening surface and making an acute angle with the first adjacent fastening portion; a distal sidewall adjoining a second adjacent fastening portion of the fastening surface and making an angle with the second adjacent fastening portion; and a ceiling wall connecting the proximal and distal sidewalls, wherein the proximal sidewall is located closer to the screw passage hole than the distal sidewall is located to the screw passage hole.

A compression milling cutter includes a shank and a front cutting portion that terminates at a leading end of the milling cutter. The front cutting portion has a first circumferential row of one or more insert receiving pockets proximate a leading end of the milling cutter, and a second circumferential row of one or more insert receiving pockets, each insert receiving pocket configured to receive a respective indexable cutting insert. The cutting insert mounted in the first circumferential row has a positive axial rake angle, A, and the indexable cutting insert mounted in an insert pocket of the second circumferential row has a negative axial rake angle, B. Because of the different axial rake angles, chips generated during a machining operation flow in opposite directions, thereby creating a compression zone disposed between the first and second circumferential rows. This compression zone replicates the cutting action of a solid end mill, particularly when machining fiber reinforced plastic materials.

The present invention provides a cutting insert 10 which is mounted on an indexable rotating tool E comprising a body B that rotates about a predetermined rotational axis AX. The cutting insert 10 comprises an upper surface 10a, a lower surface 10b and a peripheral side surface. The cutting insert 10 further comprises an inner cutting edge 10g and a corner cutting edge 10f. A top part S, which has the maximum distance from the lower surface 10b, is located on the corner cutting edge 10f.

A cutting insert has: first sub cutting edges at positions corresponding to first corner portions of a polygonal top surface; second sub cutting edges at positions corresponding to second corner portions; and main cutting edges on side portions. In a side view, each of the main cutting edges has a first cutting edge adjacent to the first sub cutting edge, a second cutting edge adjacent to the second sub cutting edge, and a third cutting edge between the first cutting edge and the second cutting edge. Each of the main cutting edges inclines such that the height thereof decreases from a portion adjacent to the first sub cutting edge to a portion adjacent to the second sub cutting edge. An inclination angle of the third cutting edge is greater than inclination angles of the first cutting edge and the second cutting edge.

The technical objective of the present invention is to provide a cutting insert that can minimize a phenomenon in which the cutting insert is lifted up from a seat surface of a cutting tool while a cutting process is being performed, and can increase an area by which the cutting insert is fastened to the cutting tool. To this end, the cutting insert of the present invention comprises: a principal surface; a fastening surface opposite to the principal surface, the fastening surface being placed on the seat surface of the cutting tool; and a screw passage hole formed through each of central portions of the principal and fastening surfaces, wherein a screw is fastened to the cutting tool through the screw passage hole; and first and second long grooves extending across the fastening surface, wherein each of the first and second long grooves includes: a proximal sidewall adjoining a first adjacent fastening portion of the fastening surface and making an acute angle with the first adjacent fastening portion; a distal sidewall adjoining a second adjacent fastening portion of the fastening surface and making an angle with the second adjacent fastening portion; and a ceiling wall connecting the proximal and distal sidewalls, wherein the proximal sidewall is located closer to the screw passage hole than the distal sidewall is located to the screw passage hole.

A substantially parallelogramatic insert having a downward inclined main cutting edge and an auxiliary cutting edge in part of a long-side ridgeline and a short-side ridgeline adjacent to a pair of corner cutting edges of an upper surface; the main cutting edge being constituted by first to third straight cutting edges; the first to third straight cutting edges being connected in a bent-line shape with inward obtuse crossing angles when viewed from above, such that the second straight cutting edge is positioned outermost; and cutting edge angles .sub.1, .sub.2, .sub.3 between the rake faces and flanks of the first to third straight cutting edges meeting the relation of .sub.1>.sub.2>.sub.3.

A minor cutting edge has a first minor cutting edge and a second minor cutting edge that extends inward of the insert in a direction of an insert short side face axial line, as the second minor cutting edge extends from the first minor cutting edge in a direction of an insert major face axial line. A flank face of the second minor cutting edge is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from the second minor cutting edge in the direction of an insert long side face axial line, and is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from a major face adjacent to the flank face in the direction of the insert major face axial line.

A milling insert suitable for shoulder milling includes a side surface extending between an upper and lower side and a cutting edge having a primary and a secondary cutting edge portion. The side surface includes an axial support surface opposite of the secondary cutting edge portion. The lower side includes a locking groove extending longitudinally, and a lower contact region formed to bear on a fastening member. The upper side has an upper contact region arranged to bear on a top support member of a tool in which the milling insert is mountable. A milling tool is provided with a top support member for bearing on the upper contact region of the milling insert, a locking ridge for locking with the locking groove, and an axial contact surface for supporting the axial support surface. A fastening member presses the milling insert against the top support member and the locking ridge.

A cutting insert has a first end surface and a second end surface which are opposed to each other. The first end surface has at least one apex and two side edges which extend so as to sandwich the apex. At least part of the two side edges serves as a cutting edge. The first end surface has a rake surface which is connected to the cutting edge. As viewed in a cross-section which intersects with the two side edges and which is orthogonal to the second end surface, the rake surface is inclined relative to the second end surface.

A cutting insert has: first sub cutting edges at positions corresponding to first corner portions of a polygonal top surface; second sub cutting edges at positions corresponding to second corner portions; and main cutting edges on side portions. In a side view, each of the main cutting edges has a first cutting edge adjacent to the first sub cutting edge, a second cutting edge adjacent to the second sub cutting edge, and a third cutting edge between the first cutting edge and the second cutting edge. Each of the main cutting edges inclines such that the height thereof decreases from a portion adjacent to the first sub cutting edge to a portion adjacent to the second sub cutting edge. An inclination angle of the third cutting edge is greater than inclination angles of the first cutting edge and the second cutting edge.