Belleville Washer (Conical Disc Spring)
Direct Answer
The Belleville Washer (Conical Disc Spring / Cupped Spring Washer, standardized under DIN 2093 and DIN 6796) is a conical annular spring disc invented by Julien Belleville in 1858. Engineered to deliver massive axial spring clamping force across microscopic deflection distances, it maintains bolted joint tension under extreme thermal expansion and dynamic vibration.
Source: DIN 2093 (Disc Springs) / DIN 6796 (Heavy-Duty Bolting) / ISO 19643
Specs
| Standard Specifications | DIN 2093 (Precision disc springs) / DIN 6796 (Heavy-duty bolted joints) / ISO 19643 |
| Conical Geometry | Frusto-conical cup shape (cone height $\approx 0.5\times$ to $0.7\times$ disc thickness) |
| Load Capacity | Extreme axial spring force (thousands of newtons in sub-millimeter stroke) |
| Stacking Capabilities | Parallel Stacking (nests together to multiply load) or Series Stacking (tips touch to multiply deflection) |
| Standard Materials | 51CrV4 chrome-vanadium spring steel / 17-7 PH stainless / Inconel 718 (high temp) |
| Primary Applications | High-voltage electrical busbars, engine cylinder heads, cryogenic piping, wind turbine bolts |
Massive Spring Force in Compact Height
While traditional coil springs require inches of axial height to generate high loads, a Belleville disc spring produces thousands of pounds of clamping force within a fraction of a millimeter of compression. In electrical transformer busbars and high-current electrical switchgear, Belleville washers maintain constant clamping pressure as copper contacts expand and contract through extreme thermal heating cycles.
Parallel vs Series Stacking Configurations
Engineers stack Belleville washers to customize spring characteristics:
- Parallel Stacking (Nesting in same direction): Multiplies spring load (2 washers = $2\times$ load, same deflection).
- Series Stacking (Opposing cup directions, apex-to-apex): Multiplies deflection stroke (2 washers = $2\times$ deflection, same load).
- Series-Parallel Combinations: Tailors custom non-linear progressive load-deflection spring curves.