Belleville vs. Flat Washer
One is a spring, the other just spreads load. Choose by whether the joint must hold preload as it settles.
| Feature | Belleville Washer | Flat Washer |
|---|---|---|
| Function | Maintains preload (spring) | Spreads load |
| Vibration resistance | Good — compensates for loosening | None |
| Installation care | Orientation matters | Either side up |
| Cost | Higher | Cheapest fastener there is |
| Best for | Thermal cycling, vibration, bearing preload | Everyday bolting |
Verdict
Use a flat washer for general assembly. Reach for a Belleville when the joint must stay tight through settling, heat, or vibration.