Belleville Washers

Direct Answer

The Belleville Washer (Conical Disc Spring / Cupped Spring Washer, standardized under DIN 2093 and DIN 6796) is a conical annular spring disc engineered to deliver massive axial spring clamping force across sub-millimeter deflection distances, maintaining bolted joint tension under extreme thermal expansion and dynamic vibration.

Source: DIN 2093 (Disc Springs) / DIN 6796 (Heavy-Duty Bolting) / ISO 19643 · Last reviewed Aug 28, 2026

Specs

Standard Specifications	DIN 2093 (Precision disc springs) / DIN 6796 (Heavy-duty bolted joints) / ISO 19643
Conical Geometry	Frusto-conical cup shape (cone height ≈ 0.5× to 0.7× 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 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× load, same deflection).
Series Stacking (Opposing cup directions, apex-to-apex): Multiplies deflection stroke (2 washers = 2× deflection, same load).
Series-Parallel Combinations: Tailors custom non-linear progressive load-deflection spring curves.