Abstract: A modular cutting tool assembly includes a tool holder (50) having at least one insert receiving pocket (52) and first (10,80) second cutting (100,102) inserts alternately receivable within the pocket (52). The first cutting (10,80) insert has a peripheral flank surface (18) configured to provide abutment features with m×n-fold rotational symmetry about the insert's central axis so that it can be restrained against the lateral support surfaces (56,58,60) in any of mn× angular positions, for at least one value of each of n and m where n≧3 and m≧2. The second cutting (100,102) insert has a peripheral flank surface (110) configured to provide reduced-symmetry abutment features with only n-fold rotational symmetry so that the second cutting insert can be restrained against the lateral support surfaces in only n angular positions.

Abstract: A cutting insert has an upper surface bounded by a cutting edge, a base, and a peripheral flank surface. The shape of the peripheral flank surface varies along the height of the cutting insert. Near the top of the peripheral flank surface, it conforms to the round or polygonal geometry of the cutting edge so as to provide support for the cutting edge. Lower down the cutting insert, the peripheral flank surface is shaped to provide transverse bearing surfaces which have considerably lower pressure angles, i.e., resistance to turning moments, than would be provided by the inherent geometry of the cutting edge. Preferably, these transverse bearing surfaces are formed by recessed features such as channels, and most preferably, as chevron-type channels. This latter possibility leads to a lower cross-sectional geometry which approximates to an n-pointed star.