A parting lathe tool for machining metal is described. This has a clamping seat for receiving a cutting insert and an internal coolant supply system for supplying coolant to a cutting zone. In this case, the coolant supply system comprises at least three coolant outlets. The coolant outlets are fluidically connected to a coolant supply port via at least two separate coolant lines running within the parting lathe tool.

A parting tool is in the form of a blade and a replaceable cutting insert, as well as, a key having an eccentric body. The cutting insert may be clamped in a seat under an elastic, resilient clamping finger. In the blade, a keyhole is formed, into which the eccentric body can be inserted. In the keyhole, there are included concave sliding surfaces, which border on a flat stop surface. With these, convex corner surfaces and flat shoulder surfaces on the eccentric body can interact. By the unique design of the keyhole and eccentric body, a gentle interaction between the surfaces is obtained, which guarantees a long service life of the blade, as well as the key.

A cutting tool comprising a holder (12) having a slot-shaped, arcuate receptacle (16), with respectively a lower and an upper bearing surface (36, 38) attached to rigid clamping jaws (18, 20) of the holder (12), for the reception (16) of a cutting insert, (14) and a cutting insert (14) having an arcuate shank (22) with lower and upper locating face (32, 34), which cutting insert is arranged exchangeably in the receptacle (16), and having a cutting head (24) with cutting edge (26), which cutting head is disposed on a workpiece-side end (44) of the shank (22), wherein the arcuate receptacle (16) and the arcuate shank (22), measured respectively on the lower bearing surface (36) of the receptacle (16) and the lower locating face (32) of the cutting insert (14), extend respectively over at least 90, wherein the receptacle (16) extends over a larger angular range than the shank (22) of the cutting insert (14), and wherein the shank (22) is held in the receptacle (16) such that the holder-side end (28) of the shank (22) is distanced from the holder-side end (30) of the receptacle (16).