CNMG120408 Insert: Dimensions, Grades & Cross References
The CNMG120408 is an ISO 1832 indexable turning insert: an 80° rhombic (C), 0° clearance, chipbreakers on both faces (double-sided), with inscribed circle d1 12.7 mm (0.5 in), thickness s 4.76 mm and 0.8 mm nose radius rε. Verify the full ordering code against the manufacturer catalogue before ordering.
Key dimensions
- Inscribed circle d1
- 12.7 mm (0.5 in)
- Thickness s
- 4.76 mm (0.187 in)
- Nose radius rε
- 0.8 mm (0.031 in)
ISO 1832 designation decoded
| Position | Meaning | Value | Explanation |
|---|---|---|---|
| 1 | Insert shape | C — Rhombic (diamond) insert, 80° included angle | Shape family: rhombic, 80°. |
| 2 | Clearance angle | N — 0° | 0° clearance (negative insert, usable on both sides) |
| 3 | Tolerance class | M | Medium tolerance class (as-sintered moulded insert, general turning) |
| 4 | Fixing / chipbreaker | G | Fixing hole, integral chipbreakers on both faces (double-sided insert) |
| 5 | Cutting edge length / IC (d1) | 12 | 12 — IC 12.7 mm (0.5 in) |
| 6 | Insert thickness (s) | 04 | 04 — 4.76 mm (0.187 in) |
| 7 | Nose corner radius (rε) | 08 | 08 — 0.8 mm (0.031 in) |
| 8 | Cutting direction | — | Hand omitted — neutral / either-hand per catalogue. |
Specification table
| ISO designation | CNMG120408 |
|---|---|
| Insert shape | Rhombic (diamond) insert, 80° included angle |
| Clearance angle | 0° — 0° clearance (negative insert, usable on both sides) |
| Tolerance class | M — Medium tolerance class (as-sintered moulded insert, general turning) |
| Fixing / chipbreaker | G — Fixing hole, integral chipbreakers on both faces (double-sided insert) |
| Inscribed circle d1 | 12.7 mm (0.5 in) |
| Thickness s | 4.76 mm (0.187 in) |
| Nose corner radius rε | 0.8 mm (0.031 in) |
| Cutting direction | Neutral / hand omitted |
| Designation standard | ISO 1832, indexable insert designation for turning and copying tools |
Source: ISO 1832 designation standard (geometry positions 1–8). Brand-specific rows below cite their manufacturer catalogue individually.
Cross-brand geometric interchange
Under ISO 1832, every insert carrying the core designation CNMG120408 shares identical geometry — shape, inscribed circle, thickness and nose radius — regardless of manufacturer. Letters after a dash (chipbreaker patterns, grade numbers) affect chip control and application band, not the pocket geometry, and are marked PARTIAL.
| Equivalent designation | Brand | Match | Note |
|---|---|---|---|
|
CNMG 12 04 08-MM 1125
ANSI: CNMG 432-MM 1125
|
Sandvik Coromant | FULL |
MM
Official catalogue ↗ · accessed 2026-09-28
|
|
CNMG 12 04 08-MR 2035
ANSI: CNMG 432-MR 2035
|
Sandvik Coromant | FULL |
MR
Official catalogue ↗ · accessed 2026-09-28
|
|
CNMG 12 04 08-PM 4325
ANSI: CNMG 432-PM 4325
|
Sandvik Coromant | FULL |
PM
Official catalogue ↗ · accessed 2026-09-28
|
|
CNMG 12 04 08-PR 4425
ANSI: CNMG 432-PR 4425
|
Sandvik Coromant | FULL |
PR
Official catalogue ↗ · accessed 2026-09-28
|
Match levels: FULL = same geometry and equivalent grade · PARTIAL = geometry matches, chipbreaker/grade differs · VERIFY = commonly quoted, confirm against the target catalogue.
Grade cross-reference (ISO 513)
Geometry swaps are safe; grade swaps need review. Grades are mapped only within the same ISO 513 workpiece group and application band, and every mapping is cited. Verified catalog mappings for this geometry are added row by row.
Grades catalogued for CNMG120408
| Brand | Grade | Chipbreaker | ISO 513 | Coating | Operation | Source |
|---|---|---|---|---|---|---|
| Sandvik Coromant | 1125 | MM | P / M / K / N / S | PVD | pre-machining with demand on surface | Catalogue ↗ (2026-09-28) |
| Sandvik Coromant | 2035 | MR | M | PVD | roughing | Catalogue ↗ (2026-09-28) |
| Sandvik Coromant | 4325 | PM | P / K | CVD | pre-machining with demand on surface | Catalogue ↗ (2026-09-28) |
| Sandvik Coromant | 4425 | PR | P / K | CVD | roughing | Catalogue ↗ (2026-09-28) |
These are the manufacturer's own grade offerings for this geometry. Cross-brand grade equivalents are published only after verification against both official catalogues; request a match below.
Applications & cutting conditions
Typical operations
- turning
- facing
- boring
- double-sided (more edges per insert)
Industry-standard 1/2 in inscribed circle — general purpose to medium roughing, widest toolholder availability.
Workpiece materials
All ISO 513 workpiece material groups (P/M/K/N/S/H) depending on the selected carbide grade.
CVD-coated grades are typical for steel (P) and cast iron (K) general turning; PVD-coated grades are typical for stainless (M), superalloys (S) and finishing cuts. Always apply the manufacturer's cutting-data recommendation for the chosen grade.
Selection notes
- ▸Geometry first, grade second. The same ISO core code is a drop-in pocket fit across brands; the chipbreaker suffix and grade decide performance and must be matched to the cut.
- ▸Nose radius is a trade-off. A larger rε strengthens the edge and allows higher feeds but raises radial cutting forces and vibration risk; smaller radii suit finishing, fine detail and slender setups.
- ▸Match clearance to the holder. Positive-clearance codes (B/C/P…) require the matching positive toolholder; 0° N inserts seat on negative holders and offer twice the edges.
- ▸Tolerance class for the job. G and tighter classes suit precision and finishing; M-class moulded inserts are the economical default for general turning.
- ▸Pick the chipbreaker for your feed band. Roughing and finishing geometries are not interchangeable in practice even when the core code is identical.
- ▸Toughness vs wear resistance. Tough grades resist interrupted cuts and scale; hard, wear-resistant grades suit stable, high-speed finishing — choose within the same ISO 513 group.
Frequently asked questions
Need verified specs or sourcing for CNMG120408?
Send the ISO code (or a brand ordering number) and your workpiece material. We reply within one business day with the verified specification and original + equivalent grade options — no obligation.
Request a quote / verificationReviewed & sources. Geometry per the ISO 1832 designation standard; brand-specific specifications cite the manufacturer catalogue shown on each row with version and extraction date. InsertBase is independent and is not an authorised distributor. Values must be verified against the current manufacturer catalogue before ordering. See the editorial & correction policy.