Engineering Tools
Reference data for specifying and sourcing fasteners correctly — the numbers a procurement or design engineer actually needs.
Finish K-factors
The nut factor (K) used in T = K × D × F. The Torque Chart assumes K=0.2 (plain/black-oxide) — use these if you know the actual finish, for a more precise figure.
| Finish | K (dry) | K (lubricated) |
|---|---|---|
| Plain / black oxide | 0.20 | 0.15 |
| Zinc plated | 0.20 | 0.16 |
| Hot-dip galvanized | 0.22 | 0.18 |
| Stainless steel (unlubricated) | 0.30+ | 0.20 |
| Dacromet / PTFE coated | 0.13 | 0.10 |