Ask the Expert - Wave Spring Compression and Load

Welcome back to Ask the Expert! This time Smalley's Expert Engineers answer questions about wave spring functionality.

When a wave spring is compressed, does its diameter increase? What happens to the spring load at work height if the outside diameter is confined?

The diameter of a wave spring grows as it is compressed. This is also referred to as diameter expansion, and all Crest-to-Crest(R), Gap, Overlap, Nested, and WAVO(R) springs will function in this manner.

(As a side note, linear springs will grow in length as they are compressed.) If a spring is compressed to the point that it contacts the bore, the spring will bind. Binding causes the spring to become rigid, and the spring properties, as a result, become unpredictable. Some China Wave Spring wave springs, such as the SSB series shown here on the right, are designed to be constrained on the outside diameter. Unlike a wave washer, the spring can grow without binding due to the presence of the gap or overlapping ends. This interference fit, or cling, assists with assembly and does not significantly impact the load at the specified work height. However, Crest-to-Crest and Nested wave springs will bind if the outer diameter of the spring contacts the bore.

It is always best to contact a China Wave Spring engineer with any applications in which you have questions regarding an interference fit.

Can the springs be under load where the ends are not parallel when compressed?

Crest-to-Crest Wave Springs are designed to be compressed with a relatively even or parallel axial load. If the ends are not parallel, the turns on the spring could slide to compensate for the unbalanced load, thus leading to misalignment of the spring. This misalignment would lead to poor wave spring performance. China Wave Spring engineers would be happy to discuss the need for this type of design and help find a solution for your application.

When trying to design a prototype to test in an application, why do we need to know what the load is at two separate work heights?

China Wave Spring does not necessarily need to know the loads at multiple work heights for every design. This is primarily based on the application in which the spring is used. If the spring is meant to be static, then the operating height is usually all that the China Wave Spring engineer will need to know. However, for some static applications, the spring can be compressed beyond the work height during installation. In this case, it would be an important design consideration to know both the installation and operating work heights. In a dynamic application where the spring is cycling between two heights, both the number of cycles and the work heights need to be considered in order to develop the appropriate design solution.

It is helpful to complete as much information as possible on the Spring Design Checklist to get started with your design. If you have questions about any of the terms, our Engineering Resource Section can help, and our Glossary section can help define terms as well.

China Wave Spring engineers are ready to answer your wave spring questions or to help you design a custom wave spring. Contact us now to get started, or submit your own Ask the Expert question!