Multi Wave Washers

Multi-Turn Wave Springs for Greater Spring Travel and Reduced Installation Height

Multi-turn wave springs are manufactured from a continuous flat spring strip. Each turn contains several waves that flatten elastically under axial compression and generate a defined spring force.

Because the total deflection is distributed over several turns, multi-turn wave springs provide considerably more spring travel than single-turn spring washers. At the same time, they often require less axial installation height than a comparable helical compression spring.

They are therefore particularly suitable for compact assemblies requiring a defined spring force and comparatively long spring travel within limited installation space.

Use the product table above to select the appropriate version by bore diameter, shaft diameter, free height, test height, spring force, spring rate, number of turns, number of waves and material.

Meaning of the Specifications in the Product Table

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

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 the spring rate:

F ≈ c × s

For the test point specified in the product table:

F1 ≈ c × (L0 − L1)

This calculation is intended for preliminary selection only. The test force F1 specified for the individual article is decisive for the final design. Manufacturing tolerances, friction, settling behaviour and the actual installation conditions may cause deviations.

How to Select the Right Multi-Turn Wave Spring

Proceed in the following order:

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

2. Determine the working height: Establish the axial height available to the spring 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 whose force F1 at a suitable test height L1 corresponds to the required force.

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

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

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

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

Difference from Single-Turn Spring Washers and Helical Compression Springs

Single-turn spring washers have only one active spring plane and are primarily suitable for short spring travel and compact preloading applications.

Multi-turn wave springs, by comparison, consist of several connected turns. The total deflection is distributed over these turns, allowing greater overall spring travel. They are manufactured as a single component and are not made up of several loose spring washers stacked together.

Compared with a round-wire helical compression spring, a multi-turn wave spring may require less axial installation height for a similar force and spring travel. It is therefore particularly suitable where:

• only limited axial installation space is available,

• a large bore or shaft diameter is required,

• a uniform axial spring force is needed,

• a helical compression spring would require too much installation height.

Whether an existing helical compression spring can be replaced directly must be assessed by comparing the spring force, spring travel, working height and installation diameters.

Number of Turns and Number of Waves

The number of turns n and the number of waves i describe different spring characteristics:

• n indicates the number of active spring turns.

• i indicates the number of waves within each turn.

A greater number of turns generally allows greater overall spring travel. The number of waves influences the force distribution and spring behaviour.

However, the number of turns and waves alone is not sufficient for product selection. The tested spring force F1, test height L1 and intended installation dimensions remain decisive.

Installation Recommendations

The spring diameter may change slightly during axial compression. The specified bore and shaft diameters must therefore be observed.

If the surrounding bore is too small, the spring may rub against the housing wall or become blocked. If the shaft is too large, it may restrict movement at the inside diameter. This can influence spring force, friction and service life.

For reliable operation, we recommend:

• providing flat and preferably parallel supporting surfaces,

• applying the load evenly in the axial direction,

• allowing sufficient clearance to the bore and shaft,

• using burr-free and rounded installation surfaces,

• guiding the spring securely against lateral displacement,

• maintaining sufficient distance from maximum compression.

Compression significantly below the test height L1 results in higher forces and material stresses. It should therefore only be carried out after technical assessment.

For frequently cycled applications, an adequate safety margin from the maximum possible spring travel is particularly important.

Materials

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 provides high strength and is suitable for many industrial applications in dry or suitably protected environments.

Without a suitable coating or protective treatment, the material is not permanently corrosion-resistant.

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 the operating temperature, contact with media, loading and required service life.

Typical Applications

Multi-turn wave springs are commonly used in:

• mechanical seals,

• pumps and compressors,

• valves and fittings,

• electric motors and gearboxes,

• clutches and brakes,

• electrical connectors,

• automotive components,

• compact return mechanisms.

They are particularly suitable for applications requiring greater spring travel and a defined axial force within a small installation height.

Custom Multi-Turn Wave Springs

In addition to the standard dimensions available from stock, multi-turn wave springs can be manufactured according to individual requirements.

Customisable characteristics include:

• bore and shaft diameters,

• spring strip width and material thickness,

• free height and working height,

• number of turns and waves,

• spring rate and spring force,

• material and surface finish.

For a technical enquiry, please provide information about the available installation space, free and installed heights, required spring force, spring travel, type of loading and operating conditions.

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

Frequently Asked Questions About Multi-Turn Wave Springs

What is a multi-turn wave spring?

A multi-turn wave spring is manufactured from flat spring strip and consists of several active turns. When compressed axially, the waves flatten elastically and generate a spring force.

Can multi-turn wave springs replace helical compression springs?

In many applications they can, particularly where axial installation height is limited. However, spring force, spring travel, working height and bore and shaft diameters must be compared.

What do bore diameter Dh and shaft diameter Dd mean?

Dh is the inside diameter of the surrounding bore or housing. Dd is the outside diameter of the shaft or mandrel. Both values are installation dimensions.

Why must the test height and test force be considered together?

The spring force changes with deflection. The force F1 therefore only applies at the corresponding height L1.

Can the spring be compressed below the test height L1?

Further compression results in higher forces and material stresses. Compression significantly below L1 should therefore only be carried out after technical assessment.