Milling tool and milling inserts having impact protection for main cutting edges

A milling tool for milling a workpiece, comprising:

• a holder defining an axis of rotation and forming a plurality of pockets around an outer periphery of a forward end thereof;
• and
• a plurality of milling inserts secured in respective ones of the pockets, each milling insert comprising a body having upper and bottom surfaces interconnected by an edge surface structure, a transition between the upper surface and the edge surface structure forming a main cutting edge structure comprised of a plurality of identical main cutting edges, the body further including a plurality of protruding portions, each protruding portion disposed at a corner toward which two of the main cutting edges converge, each protruding portion forming a secondary cutting edge disposed outside of an intersection of imaginary extensions of the two main culling edges, the secondary cutting edge being joined to a first of the two main cutting edges by a transition edge;
• the edge surface structure forming a plurality of clearance surfaces for respective ones of the main cutting edges, each clearance surface including two portions together forming a generally convex profile defining a transition crest therebetween, wherein the transition crest is situated closer to the bottom surface than to the upper surface;
• each insert including a forwardmost inactive main cutting edge having one of the clearance surfaces disposed therebehind with reference to a direction of rotation of the holder,
• a plane oriented perpendicularly to the axis of rotation and containing the transition crest of the clearance surface associated with the axially forwardmost inactive main cutting edge being disposed axially forwardly with respect to such axially forwardmost inactive main cutting edge.