An indexable lay-down cutting insert (20) comprising:
- opposing upper and lower surfaces (22, 24) with a continuous peripheral side surface (26) extending therebetween, and a central axis (A1) extending therethrough, the central axis (A1) defining an upward-to-downward direction (DU, DD), and a central body portion (30) and three circumferentially spaced apart cutting portions (32) radially protruding therefrom,
- the central body portion (30) having lower body surface (34) facing in the downward direction (DD), and three circumferentially spaced apart radially outward facing central side surfaces (36),
- each cutting portion (32) having a support surface (38) facing in the downward direction (DD), a rake surface (40) facing in the upward direction (DU), a radially outward facing relief surface (42) extending between the rake surface (40) and the support surface (38), and a cutting edge (44) formed at the intersection of the rake surface (40) and the relief surface (42), each cutting edge (44) having first and second cutting end points (NE1, NE2), and
- each cutting portion (32) further including:
- an imaginary bisector plane (PB) containing the central axis (A1) and bisecting its cutting edge (44) at a bisector cutting point (NBC);
- and
- imaginary first and second vertical planes (PV1, PV2) parallel to the imaginary bisector plane (PB) and containing the first and second cutting end points (NE1, NE2) of said each cutting portion (32), respectively,
- wherein apart from containing the first and second cutting end points (NE1, NE2), the imaginary first and second vertical planes (PV1, PV2) do not intersect their respective cutting portion (32),
- wherein, in a top view of the cutting insert (20):
- the imaginary first and second vertical planes (PV1, PV2) intersect two different central side surfaces (36) of the central body portion (30) adjacent their respective cutting portion (32) at first and second body side points (NB1, NB2), respectively;
- the first and second body side points (NB1, NB2) are located first and second cutting distances (DC1, DC2) from the first and second cutting end points (NE1, NE2), respectively;
- and
- an imaginary first circle (CC1) defined by the three cutting edges (44) circumscribes the cutting insert (20), and has a first radius (R1)
- and wherein:
- the three bisector cutting points (NBC) are located inside the imaginary first circle (CC1);
- and
- each of the first and second cutting distances (DC1, DC2) is greater than twenty-five percent of the first radius (R1).