Indexable insert for end mills

A cutting insert comprises an upper chip surface (16), a bottom surface (17) and side faces (18, 19) therebetween. At each of the end faces the cutting insert has axially protruding portions (22, 23), each of which appears with a bevel face (26, 27). Main cutting edges are provided in the intersection between the chip surface (16) and the side surfaces (18, 19). On each side surface is provided a clearance surface (30) formed on a protruding portion (31) which via a step clearance extends into a secondary helically twisted clearance surface, the chip angle of which increases with increasing cutting depth. With the cutting insert regarded in plan view the bevel face is oriented in straight angle towards the main cutting edge (24, 25). Thanks to this embodiment is achieved constant functional edge angle along a wave-shaped edge line, which combined with step clearance and large positive axial angle ( alpha ) enables improved precision when machining a 90-degree shoulder in a work piece, which contributes to a more even wear along the main cutting edge and increased life-time of the cutting insert.