Modular cutting tool assembly

A cutting insert having n-fold rotational symmetry for some value of n where n≧3, the cutting insert being indexable exclusively at n indexing stations within an insert receiving pocket which is configured to receive alternately cutting inserts having both n-fold rotational symmetry and m×n-fold rotational symmetry for some value of m where m≧2, the cutting insert comprising a unitary structure having an upper surface bounded by a cutting edge, a base, a peripheral flank surface and a central axis, wherein said peripheral flank surface is shaped such that an outline of a first cross-section taken through the lower part of the cutting insert perpendicular to said central axis exhibits a recessed form including:

• (a) n corner portions angularly spaced around said central axis, said corner portions corresponding to n-fold rotationally symmetric lateral abutment features;
• and
• (b) support protrusions protruding outwards from said peripheral flank surface between said corner portions,
• wherein said support protrusions are shaped such that, when the cutting insert is positioned within the insert receiving pocket in a first position, a plurality of said corner portions abut support surfaces of the insert receiving pocket and, when the cutting insert is rotated through an angle of less than 360°/n about said central axis from said first position, contact of said support protrusions with the support surfaces of the insert receiving pocket interferes with seating of the insert within the insert receiving pocket.

A modular cutting tool assembly comprising:

• (a) a tool holder having at least one insert receiving pocket with a base and a plurality of lateral support surfaces;
• (b) a first cutting insert receivable within said pocket, said first cutting insert having an upper surface, a bottom surface and a peripheral flank surface, said peripheral flank surface being configured to provide abutment features with m×n-fold rotational symmetry about a central axis of said first cutting insert such that said first cutting insert is configured to be restrained against said lateral support surfaces in any of m×n angular positions, for at least one value of each of n and in where n≧3 and m≧2;
• and
• (c) a second cutting insert receivable within said pocket, said second cutting insert having an upper surface, a bottom surface and a peripheral flank surface, said peripheral flank surface being configured to provide reduced-symmetry abutment features with only n-fold rotational symmetry about a central axis of said second cutting insert such that said second cutting insert is configured to be restrained against said lateral support surfaces in only n angular positions,
• wherein said peripheral flank surface of said first cutting insert is configured such that a lower cross-section taken through the lower part of said first cutting insert perpendicular to said central axis exhibits a recessed form.

A modular cutting tool assembly comprising:

• (a) a tool holder having at least one insert receiving pocket with a base and a plurality of lateral support surfaces, and having a predetermined feed direction relative to said lateral support surfaces;
• (b) a first cutting insert receivable within said pocket, said first cutting insert having an upper surface bounded by a cutting edge, a bottom surface and a peripheral flank surface, said peripheral flank surface being configured to provide abutment features with n-fold rotational symmetry about a central axis of said first cutting insert such that said first cutting insert is configured to be restrained against said lateral support surfaces in n angular positions, for at least one value of n where n≧3, said first cutting insert being configured such that, when mounted within said pocket, said first cutting insert presents a primary operative portion of said cutting edge at a first entering angle to said feed direction;
• (c) a second cutting insert receivable within said pocket, said second cutting insert having an upper surface bounded by a cutting edge, a bottom surface and a peripheral flank surface, said peripheral flank surface being configured to provide abutment features with n-fold rotational symmetry about a central axis of said second cutting insert such that said second cutting insert is configured to be restrained against said lateral support surfaces in n angular positions, said second cutting insert being configured such that, when mounted within said pocket, said second cutting insert presents a primary operative portion of said cutting edge at a second entering angle to said feed direction, said second entering angle being different from said first entering angle.