A fast reference table for matching CNC inserts to common workpiece materials. Use this as a starting point, then fine-tune with your specific operation.
Grade selection quick chart
| Material | Application | Recommended series | Grade group |
|---|---|---|---|
| Carbon steel | Rough turning | CNMG / SNMG | P10-P30 |
| Carbon steel | Finishing turning | WNMG / TNMG | P01-P15 |
| Alloy steel | Medium turning | WNMG / DNMG | P20-P40 |
| Stainless steel | Turning | WNMG / TNMG (sharp edge) | M10-M30 |
| Cast iron | Turning | CNMG / SNMG | K10-K30 |
| Aluminum | Turning / Milling | CCGT / TPGT (sharp) | N01-N10 |
| Hardened steel | Finishing | CBN grades | H01-H10 |
Reading the grade: P / M / K / N / H
The ISO letter tells you which material group the insert is designed for:
- P — steel (the most common group)
- M — stainless steel
- K — cast iron
- N — non-ferrous metals (aluminum, copper)
- S — heat-resistant alloys
- H — hardened materials
The number after the letter indicates hardness: lower numbers (P05) = harder, for finishing; higher numbers (P40) = tougher, for roughing.
Practical tips
- Steel turning: PVD or CVD coated grades both work; CVD excels at high-speed roughing.
- Stainless steel: choose sharp positive geometries to reduce work hardening and built-up edge.
- Cast iron: Al2O3-coated grades handle the abrasive wear well.
- Aluminum: uncoated sharp inserts avoid edge build-up; diamond-tipped for abrasive alloys.
Matching tool holders
The insert shape must match the holder pocket. A WNMG insert fits a WNMG-compatible holder; never force-fit a different shape — it damages both the holder and the workpiece.
For a personalized recommendation, contact us with your material, operation and machine specifications. We reply within 24 hours.