Wave Spring Washers coiled

Coiled Wave Spring Washers for Precise Preload and Tolerance Compensation

Coiled wave spring washers are single-turn wave springs formed into a ring from flat spring strip. When compressed axially, the waves flatten elastically and generate a defined spring force.

Thanks to their low installation height, they are particularly suitable for applications with limited axial space. They can compensate for manufacturing and assembly tolerances, axially preload components and reduce play, vibration and operating noise.

Typical applications include ball bearing arrangements, electric motors, gearboxes and other compact mechanical assemblies. Depending on the design, the spring washers have either an open gap or overlapping ends.

Use the product table above to select a suitable coiled wave spring washer by bore diameter, shaft diameter, free height, test height, spring force, spring rate, number of waves, design and material.

Meaning of the Specifications in the Product Table

The test height L1 and spring force F1 must always be considered together. A force value without the corresponding installation height is not sufficient for selecting a spring washer.

Determining Spring Travel and Spring Force

The spring travel is calculated from the difference between the free height L0 and the installed height L:

s = L0 − L

where:

• s = spring travel in mm,

• L0 = free height in mm,

• L = current installed or working height in mm.

Within the approximately linear working range, the spring force can be estimated using:

F ≈ c × s

For the test height L1 specified in the table:

F1 ≈ c × (L0 − L1)

This calculation is intended for preliminary selection only. The test force F1 specified for the individual article is decisive, as geometry, friction, settling behaviour and manufacturing tolerances may lead to deviations.

Spring Washers with an Open Gap or Overlapping Ends

Coiled wave spring washers are available in two basic designs.

Coiled Wave Spring Washers with an Open Gap

In this version, there is an open gap between the two ends of the spring. During compression, the spring washer can move circumferentially and expand radially.

The open design is particularly suitable for applications with restricted radial installation space, provided that the gap does not interfere with the surrounding construction.

Coiled Wave Spring Washers with Overlapping Ends

In this version, the two spring ends overlap. They are not permanently joined and can slide against one another during compression.

The overlap avoids a fully open interruption in the circumference while still allowing the necessary radial movement. This design is suitable, for example, for bearing preload applications and installations where more continuous support is required.

The table designation “closed” therefore refers to a version with overlapping ends, not to a welded or completely closed ring.

How to Select the Right Coiled Wave Spring Washer

Proceed in the following order:

1. Define the installation diameters: Determine the available bore diameter Dh and the maximum shaft diameter Dd.

2. Determine the working height: Establish the axial height available to the spring washer in the installed condition.

3. Calculate the spring travel: Subtract the intended working height from the free height L0.

4. Define the required spring force: Select a spring washer whose force F1 at a suitable test height L1 corresponds to the required preload.

5. Consider the force tolerance: Check whether both the minimum and maximum possible spring forces are acceptable for the application.

6. Select the design: Choose between an open-gap version and overlapping ends according to the installation space and supporting surface.

7. Assess the type of loading: Distinguish between static preload, occasional movement and frequently cycled dynamic loading.

8. Select the material: Consider corrosion, humidity, temperature and contact with surrounding media.

The spring washer should not be selected solely by its bore and shaft diameters. The intended working height and the required spring force at that height are equally important.

Radial Expansion During Compression

When a coiled wave spring washer is compressed axially, its diameter also changes. The open gap or movable overlap allows the spring to adapt in the circumferential direction.

The bore diameter Dh specified in the table must therefore be observed. If the spring washer is compressed in a bore that is too small and cannot expand as intended, it may bind against the bore wall. This can significantly alter the load-deflection characteristic.

Sufficient clearance must also be provided between the inside of the spring washer and the shaft or mandrel. Binding at the inside or outside diameter may result in increased forces, uneven loading and a reduced service life.

Use for Ball Bearing Preload

Coiled wave spring washers are frequently used to axially preload ball bearings. The spring washer is installed between a bearing ring and a housing or cover surface and generates a continuous axial force.

Correctly designed bearing preload can:

• reduce axial bearing clearance,

• compensate for manufacturing and assembly tolerances,

• absorb temperature-related changes in length,

• reduce vibration and operating noise,

• stabilise contact between the rolling elements and raceways.

The preload must be suitable for the bearing and the application. Insufficient force may not adequately compensate for the available clearance. Excessive preload may increase friction, heat generation and bearing wear.

Self-Retaining and Self-Centring Versions

Coiled wave spring washers can be designed on request to fit into a bore with slight radial interference.

Such a self-retaining version can:

• centre the spring washer inside the bore,

• prevent it from falling out during assembly,

• facilitate overhead or automated installation,

• eliminate the need for additional retaining elements.

This function is not automatically included in every standard spring washer. Where a self-retaining version is required, it must be specified during selection or enquiry.

Installation Recommendations

For reliable operation, we recommend:

• providing flat and preferably parallel supporting surfaces,

• loading the spring washer evenly and only in the axial direction,

• observing the specified bore and shaft diameters,

• allowing sufficient clearance for radial movement,

• avoiding sharp edges and burrs on the supporting surfaces,

• not compressing the spring below the intended working height,

• maintaining an adequate safety margin from maximum compression under dynamic loading.

The function should ideally be tested under actual installation conditions. Friction, component tolerances and surface condition can influence the spring force generated in practice.

Advantages of Coiled Wave Spring Washers

Depending on the product series, coiled wave spring washers can offer the following advantages over stamped spring washers:

• precisely definable spring forces and spring rates,

• tightly toleranced force values,

• low axial installation height,

• versions with an open gap or overlapping ends,

• adaptation to different bore and shaft diameters,

• optional self-retaining and self-centring designs,

• low material waste due to manufacture from spring strip.

The most suitable spring washer type depends on the required force, working height, installation space and permissible tolerances.

Materials for Coiled Wave Spring Washers

Depending on the dimensions, the standard versions are available in spring steel 1.1248 or stainless spring steel 1.4568.

Spring Steel 1.1248

Spring steel 1.1248 offers high strength and is suitable for many industrial applications in dry environments.

Without a suitable coating or protective treatment, the material is not permanently corrosion-resistant. The spring surface should therefore be protected against humidity and corrosive media.

Stainless Spring Steel 1.4568

Precipitation-hardening stainless spring steel 1.4568, also known as 17-7 PH, combines high strength with good corrosion resistance for many industrial applications.

Its suitability must be assessed according to temperature, contact with media, loading and the required service life.

Typical Applications

Coiled wave spring washers are commonly used in:

• ball and roller bearing arrangements,

• electric motors and generators,

• gearboxes,

• pumps and compressors,

• fans and blowers,

• automotive components,

• electrical connectors,

• measuring and control devices,

• precision mechanical assemblies,

• machinery and fixtures.

They are particularly suitable for applications requiring a precisely defined preload within a small axial installation height.

Custom Coiled Wave Spring Washers

In addition to the standard dimensions available from stock, coiled wave spring washers can be manufactured according to individual requirements.

Customisable characteristics include:

• bore and shaft diameters,

• material thickness and radial width,

• free height and working height,

• number and geometry of the waves,

• spring rate and spring force,

• open-gap or overlapping-end design,

• self-retaining fit inside the bore,

• material and surface finish.

For a technical enquiry, please provide information about the bore and shaft diameters, free and installed heights, required spring force, type of loading and operating conditions.

Further information on selection, design and application can be found in our Spring Washer FAQ.

Frequently Asked Questions About Coiled Wave Spring Washers

What is the difference between a coiled and a stamped wave spring washer?

Coiled wave spring washers are formed into a ring from flat spring strip and have either an open gap or overlapping ends. Stamped wave spring washers, by comparison, are punched from sheet material as a closed ring.

What do the bore diameter Dh and shaft diameter Dd mean?

Dh is the intended inside diameter of the bore or housing. Dd is the outside diameter of the shaft or mandrel for which the spring washer must provide clearance. These are installation dimensions and do not simply represent the freely measured outside and inside diameters of the spring.

What is the difference between test height L1 and free height L0?

L0 is the height of the unloaded spring washer. L1 is a defined compressed height at which the spring force F1 is specified.

What is the difference between an open-gap spring washer and a version with overlapping ends?

With an open-gap design, the two spring ends remain separated. With an overlapping design, the ends lie over one another but can move against each other during compression. Both versions allow the spring to adapt radially.

Can a coiled wave spring washer retain itself inside a bore?

A specially designed spring washer can fit into the bore with slight radial interference and retain itself. However, this “cling-in-bore” function is a special design feature and is not automatically included in every standard article.

Why must the test force always be considered together with the test height?

The spring force changes with deflection. The value F1 therefore only applies at the corresponding height L1. A different installed height results in a different spring force.