Clover®Dome Spring Washers

Clover®Dome Disc Springs for Increased Spring Travel

Clover®Dome disc springs are specially shaped disc springs that provide greater spring travel than conventional disc springs. They combine a compact axial design with comparatively high spring force and are therefore suitable for applications where only limited space is available but a larger tolerance or movement range must be accommodated.

Their special geometry is created by precisely positioned material cut-outs at the inside and outside diameters. This forms an almost uniformly shaped spring section around the circumference. When compressed axially, the spring can deform more than a conventional closed disc spring without requiring the installation height of a compression coil spring.

Typical applications include valves, pressure regulators, clutches, tensioning systems, bearing arrangements, bolted joints and equipment used in the aerospace, food-processing and general industrial sectors.

Use the product table above to select a suitable Clover®Dome disc spring by outside diameter, inside diameter, material thickness, free height, test height and spring force.

Meaning of the Specifications in the Product Table

The test height L1 and spring force F1 must always be considered together. The value F1 applies only at the specified height.

The spring travel to the test point is calculated as follows:

s1 = L0 − L1

The theoretical deflection to the flat position is approximately:

sflat = L0 − t

Here, t represents the material thickness. Before selecting the spring, it must be determined whether the flat position may actually be used as an operating point in the intended application.

Difference from Conventional Disc Springs

A conventional disc spring consists of a closed conical ring. It can generate high axial forces but generally offers only limited spring travel.

Clover®Dome disc springs, by comparison, contain material cut-outs at the inner and outer edges. The remaining spring sections can deform more elastically. This provides significantly greater spring travel at a comparable diameter.

Clover®Dome disc springs are particularly suitable where:

• a conventional disc spring does not provide enough spring travel,

• a compression coil spring requires too much axial installation space,

• larger dimensional and assembly tolerances must be compensated,

• a defined preload force is required over a greater distance,

• a compact spring with high force density is needed.

Their geometry and force-deflection characteristic do not correspond to the standard dimensions of disc springs to DIN EN 16983. A Clover®Dome spring should therefore not be substituted for a conventional disc spring solely on the basis of its outside and inside diameters.

Spring Travel and Force Characteristics

The force characteristic of a Clover®Dome disc spring is not linear over the complete spring travel. The spring force depends on factors including the material thickness, free height and the ratio between the cone height and material thickness.

The specified values L1 and F1 are therefore decisive for product selection. They provide a defined test and comparison point.

Fflat, by contrast, describes the force at the flat position. This value is not the same as F1 and is normally higher. A spring that generates the required force at L1 may produce a significantly greater opposing force when compressed further to the flat position.

For dynamically loaded applications, the normal operating point should not be located at the flat position without further assessment. Repeated full compression can increase material stress and reduce service life. The flat position is primarily useful as an additional reference value or for static loading conditions where the application has been designed accordingly.

How to Select the Right Clover®Dome Disc Spring

Proceed in the following order:

1. Determine the installation space: Define the maximum permissible outside diameter Da, required inside diameter Di and available axial height.

2. Define the operating height: Determine the height of the spring in its installed and loaded condition.

3. Calculate the spring travel: Establish the difference between the free height L0 and the intended operating height.

4. Determine the required spring force: Define the necessary axial force at the operating point.

5. Compare L1 and F1: Select a version whose test point is as close as possible to the intended operating point.

6. Check the maximum load: Also consider the force Fflat and any possible overload conditions.

7. Consider the type of loading: Distinguish between static, occasionally cycled and continuously dynamic loading.

8. Check the operating environment: Consider temperature, humidity, corrosion and possible contact with cleaning agents or other media.

The spring should not be selected solely according to the required final force. The force increase between the installed position, operating point and maximum compression must also suit the application.

Presetting and the Flat Position

Clover®Dome disc springs are preset during manufacture. The spring is subjected to a controlled load to reduce unwanted permanent setting during later use.

However, this does not mean that every version should be dynamically compressed to the flat position in every application. The number of load cycles, actual spring travel, ambient temperature and possible force peaks must all be considered.

In a static application, the flat position may be an acceptable operating or end position. For repeated loading, an operating point with sufficient reserve before complete compression is recommended.

Mechanical stops should prevent the spring from being loaded beyond the intended end position or being inverted in the opposite direction.

Installation and Guidance

Clover®Dome disc springs must be installed between flat and sufficiently strong contact surfaces. The load should be introduced as evenly and axially as possible.

For reliable operation, we recommend:

• flat and parallel contact surfaces,

• centred axial force application,

• sufficient clearance at the inside and outside diameters,

• avoiding lateral forces and tilting,

• clean contact surfaces without burrs, chips or contamination,

• a mechanical stop to prevent overloading,

• testing the spring under actual installation conditions.

The spring must not rest against sharp edges. Point loading or one-sided loading can alter the stress distribution and lead to premature damage.

Where the spring is guided, sufficient clearance must be provided between the spring and the guide. At the same time, the guide must not be so loose that the spring can move sideways or become misaligned.

Combining Several Springs

Depending on the application, several Clover®Dome disc springs may be combined. However, the usual rules for conventional disc spring stacks must not be transferred without technical assessment.

Contact surfaces, friction and the special geometry influence the resulting force-deflection characteristic. Where several springs are combined, identical versions should be used wherever possible, and the complete arrangement should be tested under actual operating conditions.

Where a single spring already provides the required force and travel, this is generally the simpler design and is less sensitive to friction and tolerance effects.

Material 1.4568 or 17-7PH

The Clover®Dome disc springs offered are made from the precipitation-hardening stainless spring steel 1.4568, also known as 17-7PH.

This material combines high strength with good corrosion resistance and is suitable for dynamically loaded spring components. Clover®Dome springs can therefore be used in demanding industrial applications as well as in food-processing and aerospace equipment.

Actual corrosion resistance nevertheless depends on the operating environment. Suitability must be assessed separately where the spring is exposed to chlorides, seawater, acids or aggressive cleaning agents.

The broad material temperature range stated on the product page does not automatically represent the permissible operating range of every spring. Spring travel, load, operating duration and environmental conditions must be assessed separately at extreme temperatures.

Frequently Asked Questions About Clover®Dome Disc Springs

What is the main difference from conventional disc springs?

Clover®Dome disc springs contain precisely designed material cut-outs, allowing significantly greater spring travel while maintaining a compact design.

What do L1 and F1 mean?

L1 is a defined compressed test height. F1 is the spring force generated at exactly this height.

What does Fflat mean?

Fflat is the force generated when the spring is compressed to the completely flat position. It is normally higher than the force F1 at the test point.

Can the spring be compressed to the flat position?

The springs are preset and can generally be compressed to the flat position. Whether this position may be used continuously or under dynamic loading must be assessed for the specific application.

Are Clover®Dome springs standardised to DIN EN 16983?

No. They have a proprietary geometry and should be selected according to their specific dimensions and force values.

Further information on disc springs and their force-deflection characteristics can be found in our Disc Spring FAQ.