Cutting tool and cutting insert having a mounting cut-out therefor

A cutting insert (20) comprising opposing first and second end surfaces (22a, 22b) with an insert peripheral surface (24) and a central axis (AC) extending therebetween,

• the cutting insert (20) having at least one cutting portion (26), at least one mounting cut-out (28), and a central through bore (30) extending between and intersecting the first and second end surfaces (22a, 22b),
• a median plane (M) perpendicular to the central axis (AC) is located midway between the first and second end surfaces (22a, 22b), and
• the first and second end surfaces (22a, 22b) are located on first and second sides (S1, S2) of the median plane (M), respectively,
• each of the at least one cutting portion (26) having a cutting edge (34) formed at the intersection of a rake surface (36) and a relief surface (38),
• the at least one rake surface (36) and the at least one relief surface (38) formed on the insert peripheral surface (24), at least one of the at least one rake surface (36) facing in a first rotary direction (DR1) about the central axis (AC),
• each of the at least one mounting cut-out (28) extending between and intersecting the first and second end surfaces (22a, 22b) and having a cut-out peripheral surface (40), the cut-out peripheral surface (40) including a first flank surface (42) and at least one adjacent first slope surface (44a, 44b),
• the at least one first flank surface (42) facing in a second rotary direction (DR2) about the central axis (AC) opposite to the first rotary direction (DR1), and
• one of the at least one first slope surface (44a, 44b) being a first upper slope surface (44a) located on the first side (S1) of the median plane (M), facing away from the median plane (M),
• wherein, in a cross-section taken in a first plane (P1) parallel to the central axis (AC) and transversely intersecting one of the at least one first flank surface (42) and the adjacent first upper slope surface (44a):
• the first upper slope surface (44a) extends away from the median plane (M) with increasing distance from the first flank surface (42);
• a first imaginary straight line (L1) tangential to the first upper slope surface (44a) forms an acute first slope angle (α1) with the median plane (M);
• and
• the first slope angle (α1) is greater than five degrees and less than twenty-five degrees.