Conical Disc Springs Groups, series and stacking to DIN EN 16983
This page introduces the conical disc spring that conforms to the DIN EN 16983 standard (formerly DIN 2093). If you have a query or concern, please don’t hesitate to contact us.
The German standards institute, DIN (Deutsches Institut für Normung), has integrated its work at European and international level. Its standards committees aligned German interests with those of CEN and ISO, and so DIN 2093 has been incorporated into a European standard, DIN EN 16983. There has been no substantive change.
Disc springs are conically formed annular discs that are loaded in the axial direction. They can be used as a single disc or arranged in stacks. A disc spring stack can consist of disc springs arranged in series, in parallel, or a combination of both, and we cover this briefly below.
Groups and Classifications
The standard divides disc springs into three groups by the thickness of a single disc.
| Group | Thickness of a single disc, t | Attributes & features | Cross-sectional view (click to enlarge) |
|---|---|---|---|
| 1 | less than 1.25 mm | Stamped, cold formed, corners rounded |
|
| 2 | from 1.25 mm to 6 mm | Stamped, cold formed, De and Di turned, corners radiused | |
| 3* | over 6 mm up to 14 mm | Cold or hot formed, machined all over, corners radiused, with contact flats and reduced thickness (t′) |
|
* Group 3 is one of our specialities. We also make thicker, non-standard discs (beyond 14 mm) to order.
Series A, B and C
Within each group there are three dimensional series: A, B and C. The series differ in their proportions, and so in the load characteristic (force/deflection) curves they generate, as the diagram shows.
DIN EN 16983 (formerly DIN 2093) defines the three series by these approximate ratios:
- Series A: De/t ≈ 18 and h0/t ≈ 0.4 (stiff, nearly linear)
- Series B: De/t ≈ 28 and h0/t ≈ 0.75
- Series C: De/t ≈ 40 and h0/t ≈ 1.3 (soft, strongly curved)
In all three series De/Di ≈ 2.
Reduced Thickness with Contact Flats
Increasingly we are called on to provide solutions to larger, bespoke stack requirements, and a few terms need introducing. This is covered in more depth on our Group 3 reduced-thickness disc spring design page.
Contact flats
We call the contact flat an annulus. The standard refers to it as a ground surface end, and the SAE HS-1582 Spring Design Manual as a contact bearing flat. Some call it the working surface. Whatever you call it, it serves a purpose:
- to improve the definition of the contact point at which the load is applied;
- in stack configurations, to reduce friction on the guide rod by adding stability.
Reduced thickness, t′
Using a contact flat shortens the moment arm, so the disc spring needs a greater load for the same deflection. For very practical reasons of interchangeability, which means keeping the free height of the spring and matching the loads as closely as possible, the thickness of the disc spring must be reduced. The reduced thickness is denoted t′ (“t dashed”).
Stacking: Series & Parallel
Disc springs can be stacked in series, in parallel or a combination of the two. This gives great flexibility in achieving both the working load and the deflection an application needs.
Note: by convention, values for the stack are written with a capital letter and those for a single disc spring in lower case.
Stacked in series
Where i is the number of disc springs (or packets) in series:
- the load on the stack equals the load on a single disc: F = Fsingle
- the stack deflection is the deflection of a single disc times the number of discs: S = i · s
- the unloaded stack height is the free height of a single disc times the number of discs: L0 = i · l0
Stacked in parallel
Think of how you would pack spoons neatly in a cutlery drawer, each fitting into the next to take up less space. For a single packet of n disc springs in parallel (ignoring friction):
- the load on the packet is the load of a single disc times the number of discs in parallel: F = n · Fsingle
- the deflection of the packet equals the deflection of a single disc: S = s
- the unloaded height is the free height of one disc plus (n − 1) times the thickness t (t′ for Group 3): L0 = l0 + (n − 1) · t
For a stack of i packets in series, each with n discs in parallel: F = n · Fsingle, S = i · s and L0 = i · [l0 + (n − 1) · t]. In parallel stacks, friction makes the loading force higher and the unloading force lower than calculated.
Progressive, linear & degressive load curves
One might expect an application to need a spring load that rises linearly with compression, that is, a constant spring rate. This need not be so, and other characteristics can be achieved. We can design the stack so that, beyond a certain deflection, the force needed to compress it further increases (progressive) or levels off (degressive). This is done by combining different stack configurations using the principles above.
The Key Points on Disc Springs
- They can be used alone, but are most often used in stacks.
- They are used to absorb energy or to apply a load.
- In their application they act in either a static or a dynamic manner.
- When they are used dynamically, we must always consider fatigue.
- Disc springs are made from a wide variety of spring steels and special alloys, depending on the operating conditions: the ambient temperature, the presence of corrosive substances, and electrical current or magnetic fields. See our materials page.
- Spring steel disc springs are through hardened. DIN EN 16983 requires a hardness of 42 to 52 HRC (about 412 to 544 HV).
- As important as hardening is the tempering process.
- Electroplating is discouraged, because hydrogen embrittlement can make the disc springs brittle and cause them to fail.
Technical Dimensions: DIN EN 16983 (DIN 2093)
Although we are best known for the larger Group 3 reduced-thickness disc springs with contact flats (thicknesses over 6 mm), we do cater for the smaller Group 1 and 2 sizes. All the relevant information on Group 3 disc springs is available for you to download and assess, but don’t hesitate to contact us if you need help. You can also search and filter all our sizes online.
Not sure which group or series you need?
Send us your loads, travel and installation space and we’ll recommend the right disc spring and stack.