In an embodiment, a cutting tool includes a holder and a cutting insert. The holder is elongated and includes an insert pocket that is located on a side of a first end. The cutting insert is secured to the insert pocket. The cutting tool further includes a clamp that fastens the cutting insert in the insert pocket, and a screw that comes in contact with the cutting insert and is secured to the insert pocket. The screw includes a first surface including a first engagement portion on a first surface that is located on a side of the first end. The first engagement portion is located within a through-hole included in the screw in a front view of the first end.

In an end view, a cutting insert 10 comprises a first connecting part 30A which is inclined such that the first connecting part 30A travels in a first direction as it heads away from a second peripheral side surface part 18 and approaches a fourth peripheral side surface part 22, and also comprises a second connecting part 30B which is connected to a center point serving as an end of the first connecting part 30A and which is inclined such that the second connecting part 30B travels in a third direction as it heads away from the second peripheral side surface part 18 and approaches the fourth peripheral side surface part 22. A cutting edge 24 comprises: a first cutting edge part 24A which is formed on the first connecting part 30A so as to be distant, by a first distance L1, from a virtual plane PR1 including a center point C1; a second cutting edge part 24B which has, in a side view, a concave circular-arc shape having a second curvature radius smaller than a first curvature radius and which is formed on the second connecting part 30B so as to be distant, by a second distance L2 greater than the first distance L1, from the virtual plane PR1; and a third cutting edge part 24C connecting the first cutting edge part 24A and the second cutting edge part 24B.

A cutting tool may have a columnar shape extended along a rotation axis from a first end toward a second end, and may include a holder, a first insert and a second insert. The holder may include a first pocket, a second pocket, a first flute and a second flute. The second pocket may be located closer to the second end than the first pocket. The first flute may be extended along the first pocket. The second flute may be extended along the second pocket. A first length from the rotation axis to the first flute may be smaller than a second length from the rotation axis to the second flute. An opening width of the first flute may be smaller than an opening width of the second flute.

The technical objective of the present invention is to provide a cutting insert that has an improved fastening property with a cutting tool, thereby preventing reduction of the service life. To this end, the cutting insert according to the present invention has three corners along the circumference thereof; an upper main cutting edge, which is formed on the edge between the upper surface and the first side surface, and an upper sub cutting edge, which is formed on the edge between the upper surface and the second side surface, are continuously disposed between respective corners; the lower surface has the same shape as that of the upper surface; and the angle defined between the upper main cutting edge and the upper sub cutting edge, which are placed on both sides with reference to each corner, is larger than or equal to 85? and is smaller than 90?.

A cutting insert for a rotary cutting tool has a second surface that includes a second seating surface having a shape of a flat surface. The first cutting edge has a first main cutting edge portion and a first sub cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub cutting edge portion. When viewed in a direction from the first surface toward the second surface, at least a portion of the second sub cutting edge portion is located outside the first main cutting edge portion, and at least a portion of the first sub cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub cutting edge portion and the second sub cutting edge portion has a shape of a curved line.

An indexable mill includes a tool holder and an indexable bit. The tool holder has a positioning shaft whose one side is provided with a braking block that has curved mortises. The positioning shaft is centrally provided with a threaded hole. The indexable bit is centrally provided with a positioning hole. The positioning hole of the indexable bit has its one side formed with a braking notch. The plug-socket like connection between the positioning shaft of the tool holder and the positioning hole of the indexable bit provides a first positioning function. The wrapping, curved surface contact between the braking block and the braking notch provides a second positioning function. The dual positioning enhances stability and rigidity of the combination.

Provided is a milling/cutting tool including: a tool main unit that is rotated about an axis; and a plurality of tips that are disposed at one end surface of the tool main unit with spacings therebetween in a circumferential direction about the axis of the tool main unit, wherein the individual tips are disposed so that turning rake surfaces thereof are inclined in the axial directions.

The technical objective of the present invention is to provide a cutting insert that has an improved fastening property with a cutting tool, thereby preventing reduction of the service life. To this end, the cutting insert according to the present invention has three corners along the circumference thereof; an upper main cutting edge, which is formed on the edge between the upper surface and the first side surface, and an upper sub cutting edge, which is formed on the edge between the upper surface and the second side surface, are continuously disposed between respective corners; the lower surface has the same shape as that of the upper surface; and the angle defined between the upper main cutting edge and the upper sub cutting edge, which are placed on both sides with reference to each corner, is larger than or equal to 85? and is smaller than 90?.

In an embodiment, a cutting tool includes a holder and a cutting insert. The holder is elongated and includes an insert pocket that is located on a side of a first end. The cutting insert is secured to the insert pocket. The cutting tool further includes a clamp that fastens the cutting insert in the insert pocket, and a screw that comes in contact with the cutting insert and is secured to the insert pocket. The screw includes a first surface including a first engagement portion on a first surface that is located on a side of the first end. The first engagement portion is located within a through-hole included in the screw in a front view of the first end.

A method for milling a planar surface, during which a milling cutter, an axis of rotation of which is perpendicular to a surface to be machined, is moved in a direction parallel to the plane of the surface, to machine the surface in a single machining operation, over a predetermined layer of material, using a single milling head, and the milling cutter, in a same axial position relative to the surface to be machined, simultaneously carries out rough working, at least one intermediate finishing operation, and a finishing operation over a same layer of material.