Cutting tool and undersized bore-less indexable insert therefor

An undersized, indexable single-sided cutting insert (14, 114, 214) being devoid of a through bore;

• the cutting insert comprising:
• opposite insert top and bottom surfaces (48, 148, 248, 50) and an insert peripheral surface (52) which extends therebetween, the insert top surface having a top edge (54);
• a symmetry central axis (CA) which passes through the top and bottom surfaces, and around which the cutting insert has 120 degree rotational symmetry;
• and
• exactly three main cutting edges (58, 158, 258);
• wherein:
• the cutting insert is not made of polycrystalline diamond (PCD) or polycrystalline boron (PCB);
• the cutting insert comprises an inscribed circle (IC) which tangentially contacts only and all main cutting edges, the inscribed circle (IC) having an inscribed circle diameter (ICD) of under 3.8 millimeters;
• the insert top surface (48, 148, 24) comprises an abutment protrusion (55) which extends outwardly from the top surface (48), beyond the top edge (54) in a side view of the insert, the abutment protrusion being three-sided in a plan view of the insert top surface (54);
• a top abutment surface (68) is formed on top of the abutment protrusion (55), the top abutment surface (68) comprising exactly three top abutment sub-surfaces (76) one of which is non-triangular in the plan view of the insert top surface, each top abutment sub-surface configured for abutting engagement with a clamping screw (74), the plurality of top abutment sub-surfaces (76) defining the perimeter of the top abutment surface (68);
• a deflector (57) extends from a main rake surface (170, 270) onto a side of the abutment protrusion (55), the deflector configured to deflect chips;
• the bottom surface (50) has a smaller footprint than the top surface (48, 148, 248);
• and
• the bottom surface (50) includes a planar bottom abutment surface (78).

An undersized indexable cutting insert (14, 114, 214) being devoid of a through bore;

• the cutting insert (14) comprising:
• opposite insert top and bottom surfaces (48, 148, 248, 50) and an insert peripheral surface (52) which extends therebetween, the insert top surface having a top edge (54);
• exactly three main cutting edges (58, 158, 258) associated with the top edge (54);
• a symmetry central axis (CA) which passes through the insert top and bottom surfaces (48, 148, 248, 50);
• and
• an abutment protrusion (55) having a top abutment surface (68) formed on top of the abutment protrusion (55), the top abutment surface (68) configured for abutting engagement with a clamping screw (74);
• wherein:
• the top abutment surface (68) is non-planar and comprises a plurality of top abutment sub-surfaces (76);
• the plurality of top abutment sub-surfaces (76) are circumferentially sloped relative to the symmetry central axis (CA) and separated from one another by a radially extending step discontinuity characterized by a difference in height of opposing radially extending edges belonging to circumferentially adjacent top abutment sub-surfaces (76);
• and
• the cutting insert (14, 114, 214) comprises an inscribed circle (IC) which tangentially contacts only and all main cutting edges (58, 158, 258) and has an inscribed circle diameter (ICD) of under 3.8 millimeters.

An indexable cutting insert (14, 114, 214) being devoid of a through bore;

• the cutting insert (14) comprising:
• opposite insert top and bottom surfaces (48, 148, 248, 50) and an insert peripheral surface (52) which extends therebetween, the insert top surface having a top edge (54);
• exactly three main cutting edges (58, 158, 258) associated with the top edge (54);
• a symmetry central axis (CA) which passes through the insert top and bottom surfaces (48, 148, 248, 50);
• and
• an abutment protrusion (55) having a top abutment surface (68) formed on top of the abutment protrusion (55), the top abutment surface (68) configured for abutting engagement with a clamping screw (74);
• wherein:
• the top abutment surface (68) is non-planar and comprises a plurality of top abutment sub-surfaces (76);
• the plurality of top abutment sub-surfaces (76) are circumferentially sloped relative to the symmetry central axis (CA) and separated from one another by a radially extending step discontinuity characterized by a difference in height of opposing radially extending edges belonging to circumferentially adjacent top abutment sub-surfaces (76);
• and
• the cutting insert (14, 114, 214) comprises an inscribed circle (IC) which tangentially contacts only and all main cutting edges (58, 158, 258).