Disc Springs: High Force in Minimal Space
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When a design needs a lot of force but has almost no room for spring travel, a coil spring is often the wrong tool. A disc spring, also called a Belleville washer, can carry several tonnes on a footprint the size of a washer and with only a few millimetres of height.
This guide explains how disc springs work, how to read their dimensions, and how to combine them to get exactly the force and travel you need.
What Is a Disc Spring?
A disc spring is a conical, washer-shaped spring. When it is loaded axially, the cone flattens and the spring stores energy. Because the material is loaded across the whole disc, a disc spring delivers a very high force for its size, typically much higher than a compression spring that fits in the same space.
Typical applications include:
- Bolted joints that must keep their preload despite settling or temperature changes
- Valves, clutches and brakes
- Bearing preload
- Tooling, punches and fixtures
- Shock absorption in heavy machinery
The Key Dimensions
Disc springs are specified with a small set of dimensions:
| Symbol | Meaning |
|---|---|
| Do | Outer diameter (mm) |
| Di | Inner diameter (mm) |
| t | Material thickness (mm) |
| L0 | Unloaded length: the free height of the disc (mm) |
| L1 | Loaded length: the test height at which the force is given (mm) |
| F1 | Force at loaded length L1 (N) |
The travel to the test point is simply s = L0 - L1.
One important difference from coil springs: the force of a disc spring does not increase linearly with travel. That is why disc springs are not specified with a constant spring rate (N/mm). Instead, compare F1 at L1 with the force and working height your design needs.
EN 16983 (Formerly DIN 2093): Groups and Series
Most metric disc springs are made to or similar to EN 16983, which replaced the well-known DIN 2093. The standard sorts disc springs in two ways.
Groups depend mainly on the material thickness:
- Group 1: t below 1.25 mm
- Group 2: t from 1.25 mm up to and including 6 mm
- Group 3: t over 6 mm and up to 14 mm. Versions with machined bearing surfaces have a slightly reduced thickness t' by design.
Series describe the stiffness of the disc:
- Series A: high force with comparatively short travel
- Series B: medium force and medium travel
- Series C: lower force with longer travel
Permissible force and dimensional tolerances depend on group and dimensions, so always check the data for the individual product.
Belleville Springs in Imperial Sizes
Alongside the metric range, there are Belleville disc springs in imperial (inch-based) dimensions. They fill the gaps between metric sizes and are often used when replacing American or British parts.
Never swap a Belleville spring for a metric one based on diameter alone. Compare thickness, unloaded length, loaded length and force as well.
Stacking: Series, Parallel or Both
The real strength of disc springs is that they can be combined.
- In parallel (all discs facing the same way): the forces add up approximately, while the travel stays the same as for one disc.
- In series (discs facing alternately): the travel adds up approximately, while the force stays the same as for one disc.
- Combined: stacks of parallel pairs placed in series give both more force and more travel.
Example: a 50 × 25.4 × 2 mm disc spring (series B, group 2) has L0 3.4 mm and F1 = 4,762 N at L1 2.35 mm, so the travel to the test point is 1.05 mm.
| Configuration | Approx. force | Approx. travel |
|---|---|---|
| 1 disc | 4,762 N | 1.05 mm |
| 2 discs in parallel | about 9,500 N | 1.05 mm |
| 4 discs in series | 4,762 N | about 4.2 mm |
| 4 parallel pairs in series (8 discs) | about 9,500 N | about 4.2 mm |
These are approximations. Friction between the discs increases with every extra disc in a stack, so use as few discs as reasonably possible and, as a rule, identical discs within one stack.
Choosing a Material
- Spring steel (Ck67, Ck75) and chrome vanadium steel 51CrV4: high strength for most industrial applications. They need corrosion protection; phosphated and oiled versions only give limited protection in dry environments.
- Stainless steel 1.4310 (AISI 301): suitable for humid environments, but only to a limited extent for permanent contact with seawater or chlorides.
- Stainless steel 17-7 PH (1.4568): a precipitation-hardening stainless steel with high strength, well suited to dynamically loaded applications.
Installation Tips
- Use flat, parallel and sufficiently hard supporting surfaces.
- Guide the discs on the inner or outer diameter with enough clearance.
- Load the stack axially and avoid side forces and tilting.
- Lubricate stacked discs with oil, grease or a solid lubricant.
- In dynamic applications, do not regularly compress the discs completely flat. A mechanical stop can limit the travel.
How to Find the Right Disc Spring at AxiSpring
AxiSpring offers close to 600 disc springs, from small Belleville washers under 5 mm to EN 16983 disc springs of 200 mm outer diameter, in spring steel, chrome vanadium steel and stainless steel. In the disc spring catalog you can filter by outer and inner diameter, thickness, unloaded length L0, force F1, standard and material. Every product page has a dimension drawing and a downloadable datasheet.
Not sure which disc spring or stack suits your design? Contact us or ask Springy, our spring assistant, directly on the site.