The relief surface and the rake surface form a first angle.

The substrate has a rake surface (16) and a flank surface (14) wherein there is a cutting edge (18) at the intersection of the rake surface and the flank surface.

At least one side face is provided with a first, possibly helically twisted relief surface and under this first relief surface, a secondary relief surface.

The cutting portion has a rake surface (26), a relief surface (28) and a cutting edge (24) defined at the intersection between the rake surface (26) and the relief surface (28).

It comprises a top surface, a round clearance surface (2) and a bottom surface (3).

The cutting edge is formed at the intersection of a rake surface and a relief surface.

Adjacent each major cutting edge, in each major side surface, is a primary relief surface (50).

The primary relief surface forms with the associated side abutment surface a primary relief surface angle that varies from a maximal value adjacent an upper end (58) of the primary cutting edge to a minimal value.

The relief surface (20) having a plurality of recesses (26) extending to the chip rake surface (22).

A deflecting surface is formed adjacent the rake surface and generally transverse thereto.

The clearance surface of the corner blade has a variable-angle surface part in which the clearance angle varies continuously from the bottom blade side to the outer peripheral blade side.

A clearance surface (28) is provided opposite the first contact point (38).

Each of the plurality of abrasive grains (210) comprises a relief surface (216) which has a relief angle equal to a predetermined angle (β).

Each flute includes a rake surface intersecting with the outer surface to form a cutting edge, and a relief surface opposite the rake surface.

The upper side (11) comprises a chip surface comprising at least one chip breaker portion (18) and said edge surface constitutes a clearance surface.