Indexible cutting insert for end mills

Milling tool for rotary machining of metallic workpieces, the tool having a cylindrical tool body rotatable around a center axis, a rear part of the tool body provided with a shank portion adapted to be rotatably clamped in a driver, a periphery of the tool body having a number of circumferentially spaced recesses, each recess confined by a bottom support surface and at least one side support surface upstanding therefrom that extends in axial and radial directions, the tool further comprising indexible inserts releasably clamped in the tool body, each insert comprising a basically parallelogram shaped insert body including a top surface, a planar bottom surface, two longitudinal side surfaces intersecting the top face to form respective main cutting edges therewith, and two end faces each having a bevel provided on a portion of the body protruding longitudinally from the remainder of the insert body, each of the side surfaces having a width increasing toward a respective active cutting corner of the insert such that active cutting corner is raised, the side surfaces being generally inclined at an acute angle toward the top face and at an obtuse angle toward the bottom surface, an upper portion of each of the side surfaces comprising a wave-shaped primary clearance surface extending along the entire respective main cutting edge at a downward inclination from one end face toward the other end face, the primary clearance surface being provided on a portion of the insert body extending laterally from the remainder of the insert body, each primary clearance surface forming a step with a lower portion of the respective side surface, the lower portion of each side surface comprising a secondary helically twisted clearance surface, the upper portion of each side surface defining a clearance angle with a normal to the bottom surface, the clearance angle increasing in size as a distance from the respective active cutting corner increases, the bevels being separated from the main cutting edge by a smoothly curved edge portion, each insert oriented to form a positive axial angle and a negative radial angle.