Turning insert designation (ISO 1832)
Type the code from the box or the catalog — metric (CNMG 120408-PM) or inch (CNMG 432) — and see what each character means.
Quick answer
CNMG 120408: C — 80° diamond, N — 0° clearance, M — standard tolerance, G — hole, chipbreaker on both faces, 12 — 12.7 mm (1/2″) inscribed circle, 04 — 4.76 mm thick, 08 — 0.8 mm nose radius. The inch equivalent is CNMG 432 (1/2″ IC, 3/16″ thick, 1/32″ radius).
How the code reads
Take CNMG 120408-PM: C — shape, N — clearance angle, M — tolerance class, G — type (hole and chipbreaker), 12 — size, 04 — thickness, 08 — nose radius. Edge condition (F, E, T, S) and hand (R, L, N) may follow. Anything after the dash (-PM, -WM, -MF) is the maker's own chipbreaker and is not part of the standard.
The inch (ANSI) code differs in the digits: CNMG 432 means an inscribed circle of 4/8″ = 1/2″, thickness 3/16″, radius 2/64″ = 1/32″. It is the same insert as CNMG 120408.
1. Shape
| C | 80° diamond |
| D | 55° diamond |
| V | 35° diamond |
| E | 75° diamond |
| M | 86° diamond |
| S | square 90° |
| T | triangle 60° |
| W | 80° trigon |
| R | round |
| A | 85° parallelogram |
| B | 82° parallelogram |
| K | 55° parallelogram |
| H | hexagon |
| O | octagon |
| P | pentagon |
| L | rectangle |
2. Clearance angle
| N | 0° |
| A | 3° |
| B | 5° |
| C | 7° |
| P | 11° |
| D | 15° |
| E | 20° |
| F | 25° |
| G | 30° |
| O | other |
N (0°) is a negative insert, usually double-sided. C and P are positive, good for boring and light machines.
3. Tolerance class
| M | pressed, standard accuracy — the most common |
| G | ground periphery, tighter than M |
| U | pressed, looser than M |
| E, H, K, J, F, C, A | precision classes (ground) |
4. Type: hole and chipbreaker
| N | no hole, no chipbreaker |
| R | no hole, chipbreaker on one face |
| F | no hole, chipbreaker on both faces |
| A | with hole, no chipbreaker |
| M | with hole, chipbreaker on one face |
| G | with hole, chipbreaker on both faces |
| W | hole with one countersink (for a screw) |
| T | hole with one countersink, chipbreaker on one face |
| B, C, Q | hole with countersinks, no chipbreaker |
| H, J, U | hole with countersinks and chipbreaker |
| X | special design |
5. Size (common inserts)
Two digits — cutting edge length in mm without decimals. For round inserts — the diameter.
| Shape | Code | Inscribed circle | ANSI |
|---|---|---|---|
| C | 09 | 9.525 mm | 3 |
| C | 12 | 12.7 mm | 4 |
| C | 16 | 15.875 mm | 5 |
| C | 19 | 19.05 mm | 6 |
| D | 11 | 9.525 mm | 3 |
| D | 15 | 12.7 mm | 4 |
| S | 09 | 9.525 mm | 3 |
| S | 12 | 12.7 mm | 4 |
| S | 15 | 15.875 mm | 5 |
| S | 19 | 19.05 mm | 6 |
| T | 16 | 9.525 mm | 3 |
| T | 22 | 12.7 mm | 4 |
| T | 27 | 15.875 mm | 5 |
| V | 16 | 9.525 mm | 3 |
| V | 22 | 12.7 mm | 4 |
| W | 06 | 9.525 mm | 3 |
| W | 08 | 12.7 mm | 4 |
6. Thickness
| ISO | mm | ANSI |
|---|---|---|
| T0 | 1.00 | .6 |
| 01 | 1.59 | 1 |
| T1 | 1.98 | 1.2 |
| 02 | 2.38 | 1.5 |
| T2 | 2.78 | — |
| 03 | 3.18 | 2 |
| T3 | 3.97 | 2.5 |
| 04 | 4.76 | 3 |
| 05 | 5.56 | — |
| 06 | 6.35 | 4 |
| 07 | 7.94 | 5 |
| 09 | 9.53 | 6 |
7. Nose radius
| ISO | mm | ANSI |
|---|---|---|
| 01 | 0.1 | — |
| 02 | 0.2 | 0.5 |
| 04 | 0.4 | 1 |
| 08 | 0.8 | 2 |
| 12 | 1.2 | 3 |
| 16 | 1.6 | 4 |
| 20 | 2.0 | 5 |
| 24 | 2.4 | 6 |
| 32 | 3.2 | 8 |
| M0 / 00 | round insert (no radius) | — |
8. Edge condition (optional)
| F | sharp |
| E | honed |
| T | chamfered (T-land) |
| S | chamfered and honed |
9. Hand (optional)
| R | right hand |
| L | left hand |
| N | neutral (both directions) |
Compiled from ISO 1832 as presented in tooling manufacturers' references. Exact tolerance values, carbide grade and chipbreaker use are in the insert maker's catalog.
The nose radius sets the surface finish — work it out from the feed in the surface finish calculator.