Cutting insert and holder for metal cutting machining

A tool for metal cutting machining comprising:

• a holder arrangement including a shim which defines an insert-receiving site for receiving a cutting insert, the site including an upwardly facing bottom support surface and at least two generally upright support surfaces disposed in non-parallel relationship;
• an indexable cutting insert seated on the site and including an upwardly facing chip surface, a downwardly facing abutment surface, and a side surface structure intersecting the chip surface to form therewith a cutting edge structure, the side surface structure defining an outer perimeter of the insert, the generally downwardly facing abutment surface disposed inside of the outer perimeter and abutting the bottom support surface of the site, the insert further including at least three generally upright abutment surfaces disposed inside of the outer perimeter, at least two of the generally upright abutment surfaces being disposed in facing relationship to respective ones of the generally upright support surfaces;
• and
• a tightenable insert-securing device extending through a hole in said shim arranged for generating a first force oriented in a first direction substantially perpendicular to a plane of the insert and which presses the downwardly facing abutment surface against the upwardly facing support surface, and a second force oriented for pressing at least two, but less than all, of the generally upright abutment surfaces against respective ones of the generally upright support surfaces, said hole positioned so as to generate the second force extending in a single second direction parallel to the plane of the insert and forming an oblique angle with each of the at least two generally upright abutment surfaces when said insert-securing device is inserted therein and tightened;
• the insert, upon loosening of the insert-securing device, being indexable to bring another portion of the cutting edge structure into active cutting position, the generally upright abutment surfaces arranged such that in response to indexing of the cutting insert and a re-tightening of the insert-securing device:
• the first and second forces are re-generated in the same first and second directions, respectively;
• one of the generally upright abutment surfaces previously disposed out of engagement with a generally upright support surface is moved into abutment with a generally upright support surface by the second force, and
• a generally upright abutment surface previously in abutment with a generally upright support surface is moved out of abutment with all of the generally upright support surfaces.