Professional roughing of stainless steel
The indexable insert SNMG-MR RT255M is a highly resilient solution for demanding turning operations. Combining a sturdy, square basic shape with the advanced PVD coating of the M20-M30 carbide grade, it is perfectly suited for medium machining and roughing of stainless steels. The eight available cutting edges promote cost-effective tool utilization, while the MR chipbreaker ensures proper chip control during both continuous and light interrupted cuts.
Suitable materials

Technical data
- Insert shape: SNMG (square, negative)
- Processing: Medium machining and roughing
- Cutting conditions: Continuous and light interrupted
- Recommended material: Stainless steel
- Carbide grade: RT255M (PVD-coated M20-M30)
- Packaging unit: 10 pieces
Dimensions of SNMG-MR RT255M
| |
Item Nr. |
r |
L |
I.C |
S |
d |
| SNMG 120404-MR RT255M |
1661671 |
0,4 |
12,7 |
12,7 |
4,76 |
5,16 |
| SNMG 120408-MR RT255M |
1661672 |
0,8 |
12,7 |
12,7 |
4,76 |
5,16 |
| SNMG 120412-MR RT255M |
1661673 |
1,2 |
12,7 |
12,7 |
4,76 |
5,16 |
Cutting data
|
Stainless Steel |
|
Vc (m/min) |
fn (mm/U) |
ap (mm) |
| SNMG 120404-MR RT255M |
80-200 |
0,2-0,4 |
0,5-4 |
| SNMG 120408-MR RT255M |
80-200 |
0,2-0,4 |
0,5-4 |
| SNMG 120412-MR RT255M |
80-200 |
0,2-0,4 |
0,5-4 |
Applications
The SNMG-MR RT255M is predominantly used in industrial machining when stainless steel components require roughing or medium turning operations. It is exceptionally well-suited for longitudinal and facing cuts on CNC machines where high material removal rates and process stability are essential. Thanks to its tough design, the cutting insert confidently handles light cut interruptions, opening up flexible application possibilities in series production.
Special features
A key characteristic of this turning insert is the state-of-the-art PVD coating of the RT255M grade, which reduces tool wear and enhances temperature stability when cutting stainless materials. The MR geometry supports smooth chip evacuation, minimizing the risk of chip jamming and unexpected tool breakage. Furthermore, the eight cutting edges of the negative design offer an excellent price-performance ratio for the professional user.