A method to form a surface on a metal work piece includes providing a turning insert having a first cutting edge, a second cutting edge and a convex nose cutting edge connecting the first and second cutting edges, a nose angle formed between the first and second cutting edges being less than or equal to 85; arranging the second cutting edge such that it forms a back clearance angle of more than 90 in a feed direction; positioning all parts of the turning insert ahead of the nose cutting edge in the feed direction; rotating the metal work piece around a rotational axis in a first direction; and moving the turning insert in a direction parallel to or at an angle less than 45 relative to the rotational axis, such that the surface at least partly is formed by the nose cutting edge.

A cutting insert may include an upper surface, a lower surface, a front lateral surface and a rear lateral surface. The upper surface may include an upper constraining surface. The lower surface may include a lower groove having a V-shape. The lower groove may include a first region, a second region, a third region a first portion and a second portion. A length of a line segment connecting the first portion and the second portion in the first region may be a first length, a length of a line segment connecting the first portion and the second portion in the second region may be a second length, and a length of a line segment connecting the first portion and the second portion in the third region may be a third length. The first length may be larger than each of the second length and the third length.