Description
TNMG or CNMG – The Real Trade-Off
The TNMG 160408 is the most common turning insert question and the answer is genuinely about the job, not about price.
- TNMG gives six corners against four, so the cost per cutting edge is roughly a third lower for the same insert price.
- CNMG has a stronger corner. The 80 degree included angle puts far more carbide behind the cutting point than the 60 degree triangle does. On heavy roughing, on interrupted cuts, or on scaled bar stock, that difference decides whether the corner survives.
- The practical rule – use TNMG for general turning, facing and light to medium roughing on clean material where you want the most edges for the money. Use CNMG when the cut is heavy, interrupted, or on scale.
Shops that run TNMG on heavy interrupted work to save money almost always spend more, because they lose corners to fracture rather than wearing them out.
Specifications of TNMG 160408
| Attribute | Value |
|---|---|
| Designation | TNMG 160408 HM |
| Grade | PC9030 |
| Insert shape | Triangular, 60 degree (ISO T) |
| Clearance angle | N, zero degrees – negative, double sided |
| Cutting edge length | 16 mm nominal per ISO code |
| Inscribed circle | 9.525 mm |
| Thickness | 4.76 mm |
| Nose radius | 0.8 mm |
| Usable corners | 6 |
| Chipbreaker | HM, medium duty |
| ISO grade range | M25 to M35 |
