Cutting insert and tool for machining a workpiece

A tool for machining a workpiece, having a tool holder which comprises at least one cutting insert receptacle in which a cutting insert is releasably fastened, the cutting comprising:

• two identical parts, a first part and a second part;
• a through-bore which runs through both parts along a bore axis;
• two identical, oppositely arranged base sides, a first base side which is part of the first part and comprises a first planar support surface which runs orthogonally to the bore axis, and a second base side which is part of the second part and comprises a second planar support surface which runs orthogonally to the bore axis;
• four identical main sides which extend between the two base sides, wherein each of the four main sides comprises a planar contact surface which runs orthogonally to the first and the second support surface;
• precisely four rectilinear main cutting edges, wherein precisely one of the four main cutting edges is arranged on each of the four main sides, respectively, and each of the two parts comprises two of the four main cutting edges, respectively, wherein the two main cutting edges of the first part run parallel to one another, and wherein the two main cutting edges of the second part run parallel to one another and at an acute angle to the main cutting edges of the first part;
• precisely four rectilinear secondary cutting edges, wherein precisely one of the four secondary cutting edges is arranged on each of the four main sides, respectively, and each of the two parts comprises two of the four secondary cutting edges, respectively, and wherein the secondary cutting edges run transversely to the main cutting edges;
• wherein the two parts are connected together along a center plane which runs orthogonally to the bore axis and at an identical distance from the first support surface and the second support surface, respectively, and wherein the first part is projected onto the second part as a result of rotation by 180° about a rotational axis lying in the center plane and a subsequent rotation by the acute angle about the bore axis;
• wherein each of the four main cutting edges is connected at a first end to one of the four secondary cutting edges, which is arranged on the respective same main side, via a first corner edge, which comprises a radius and/or a chamfer, and
• wherein each of the four main cutting edges is arranged with the secondary cutting edge, arranged on the respective same main side, in a common cutting plane which is aligned parallel to the contact surface arranged on the respective same main side, wherein each of the contact surfaces is offset toward the central bore axis in relation to the cutting plane arranged on the respective same main side.