DIN 9250 — Serrated Lock Washers
DIN 9250German serrated lock washer standard, with toothed and non-toothed variants. Serrations form a circular array, 6-24 teeth (size-dependent). Teeth slide during tightening; tooth edges embed into the mating surface to prevent loosening. Suitable for grade 8.8/10.9 bolted joints under alternating loads and vibration. Material C75S/51CrV4.
Clause Summaries
Scope
Applies to M2-M30 metric bolted joint anti-loosening. Operating temperature -40°C~+150°C (phosphated) or -40°C~+300°C (plain/silver-plated).
Serration Design & Locking Mechanism
Serration angle 60°-90°, tooth height 0.15-0.3mm. Locking mechanism: bolt preload elastically flattens serrations; under vibration, serrations try to spring back and embed, creating mechanical lock. Unlike DIN 127 spring washer, DIN 9250 relies on serration locking, not spring resilience.
Dimension Table
| de | di | force | group | h0 | t | weight_per_1000 |
|---|---|---|---|---|---|---|
| 9 | 4.3 | 620 | S4 | 0.25 | 0.8 | 0.2 |
| 10 | 5.3 | 950 | S5 | 0.3 | 1 | 0.32 |
| 12 | 6.4 | 1450 | S6 | 0.35 | 1.2 | 0.52 |
| 16 | 8.4 | 2600 | S8 | 0.45 | 1.6 | 1.1 |
| 20 | 10.5 | 4200 | S10 | 0.55 | 2 | 2.1 |
| 24 | 13 | 6400 | S12 | 0.7 | 2.5 | 3.6 |
| 30 | 17 | 10500 | S16 | 0.85 | 3 | 6.9 |