Belleville Washer
Washers · conical spring washer · disc spring · Belleville spring
Definition: A Belleville washer is a conical disc spring that flattens under load, maintaining a predictable preload and compensating for joint settling, thermal expansion, and vibration.
Anatomy
■ Body■ Hole
Governing standards: DIN 6796
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| for 1/4 bolt | M6 | 0.50 OD | 0.026 thick |
| for 3/8 bolt | M10 | 0.79 OD | 0.047 thick |
| for 1/2 bolt | M12 | 1.02 OD | 0.063 thick |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Spring steel | spring steel, zinc-plated | — | None |
| Stainless | 301 / 304 spring stainless | — | None |
Materials
- Spring steel (zinc-plated)
- 301 / 304 spring stainless
- Phosphor bronze
Pros & Cons
Pros
- Maintains preload far better than a split washer
- Predictable load-deflection curve
- Stackable for more travel or force
Cons
- Must be oriented and sized correctly
- Over-flattening loses the spring effect
- Pricier than a flat washer
Typical Uses
- High-vibration bolted joints
- Thermal expansion compensation
- Bearing preload
- Clutch and valve stacks
Alternatives & Related
- Flat Washer — Simple load spreading, no spring effect
- Wave Washer — Lighter preload in a thin profile
Where to Buy
Affiliate links — we may earn a commission at no cost to you.
FAQ
Belleville washer vs split lock washer?
A Belleville washer is a true spring that maintains preload as the joint settles; a split lock washer mostly flattens flat at assembly and provides little residual spring force.
How should a Belleville washer be oriented?
For a single washer, the convex side faces the bolt head or nut. For stacks, use series (//) for more force or parallel ()() for more travel.