Rotationally asymmetric double-ended grooving cutting insert, insert holder and cutting tool

A double-ended cutting insert (22) comprising:

• opposing first and second relief face surfaces (28a, 28b) and an insert peripheral surface (30) extending therebetween about an insert longitudinal axis (A), the insert peripheral surface (30) comprising a first rake face surface (34a) and an opposing first support face surface (36a), and a second rake face surface (34b) and an opposing second support face surface (36b), which all connect the first and second relief face surfaces (28a, 28b);
• a first insert central axis (C1) oriented perpendicular to the insert longitudinal axis (A) and extending through the first rake face surface (34a) and the first support face surface (36a);
• a second insert central axis (C2) oriented perpendicular to both the first insert central axis (C1) and the insert longitudinal axis (A), and extending through the second rake face surface (34b) and the second support face surface (36b);
• a first cutting edge (44a) formed at an intersection of the first relief face surface (28a) and the first rake face surface (34a);
• a second cutting edge (44b) formed at an intersection of the second relief face surface (28b) and the second rake face surface (34b);
• a first rake engagement groove (48a) recessed in the first rake face surface (34a) and extending along a first rake longitudinal axis (RG1), the first rake engagement groove (48a) opening out to the second relief face surface (28b);
• a first support engagement groove (50a) recessed in the first support face surface (36a) and extending along a first support groove longitudinal axis (SG1), the first support engagement groove (50a) opening out to the second relief face surface (28b);
• a second rake engagement groove (48b) recessed in the second rake face surface (34b) and extending along a second rake longitudinal axis (RG2), the second rake engagement groove (48b) opening out to the first relief face surface (28a);
• a second support engagement groove (50b) recessed in the second support face surface (36b) and extending along a second support groove longitudinal axis (SG2);
• the second support engagement groove (50b) opening out to the first relief face surface (28a);
• wherein:
• the first rake longitudinal axis (RG1) and the first support engagement groove longitudinal axis (SG1) converge towards each other in a direction from the first relief face surface (28a) towards the second relief face surface (28b), thereby defining an acute first groove wedge angle (θ1);
• the second rake longitudinal axis (RG2) and the second support engagement groove longitudinal axis (SG2) converge towards each other in a direction from the second relief face surface (28b) towards the first relief face surface (28a), thereby defining an acute second groove wedge angle (θ2);
• the first support engagement groove (50a) is intersected by a first insert bisector plane (B1) containing the insert longitudinal axis (A) and the first insert central axis (C1);
• the second support engagement groove (50b) is intersected by a second insert bisector plane (B2) containing the insert longitudinal axis (A) and the second insert central axis (C2);
• for at least one-half its length, the first support engagement groove (50a) is mirror symmetric about the first bisector plane (B1);
• and
• for at least one-half its length, the second support engagement groove (50b) is mirror symmetric about the second bisector plane (B2).