A cutting insert including a body having three vertices, an upper face, a lower face, and flank faces joining the upper and lower faces. At least one cutting edge is formed at an intersection between the upper face and the flank faces. A generally triangular-shaped island surrounds a central axis of the cutting insert and is higher in elevation than at least one portion of the upper face.

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 turning insert includes a top surface, an opposite bottom surface, side surfaces connecting the top surface and the bottom surface and two opposite nose portions. Each nose portion includes a convex nose cutting edge, a first cutting edge and a second cutting edge. The convex nose cutting edge connects the first and second cutting edges. A bisector extends equidistantly from the first and second cutting edges. In a top view the first and second cutting edges on the same nose portion form a nose angle () of 70-85 relative to each other. Each nose portion includes a third convex cutting edge adjacent to the first cutting edge and a fourth cutting edge adjacent to the third cutting edge. In a top view the fourth cutting edge forms an angle () of 0-34 relative to the bisector.

A turning insert includes a top surface, an opposite bottom surface, side surfaces connecting the top surface and the bottom surface and two opposite nose portions. Each nose portion includes a convex nose cutting edge, a first cutting edge and a second cutting edge. The convex nose cutting edge connects the first and second cutting edges. A bisector extends equidistantly from the first and second cutting edges. In a top view the first and second cutting edges on the same nose portion form a nose angle () of 70-85 relative to each other. Each nose portion includes a third convex cutting edge adjacent to the first cutting edge and a fourth cutting edge adjacent to the third cutting edge. In a top view the fourth cutting edge forms an angle () of 0-34 relative to the bisector.

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.