Wave spring substitution, compression and performance
The experts at TFC guide us through some of the commonly asked questions about wave springs and their performance.
Wave springs save space without compromising on force or deflection which opens up a whole host of applications where they can be real problem solvers. A good example was the replacement of six pocketed coil springs that load a coupling connection, that were proving difficult to handle and which would easily clog with dirt.
For a coupling connection, a single wave spring can be designed to work along the circumference of the housing and remove the need for individually pocketed springs. Often a standard, off-the-shelf item can serve this need, but to achieve exact requirements TFC can look at a bespoke design.
Wave springs save space when compared to a coil spring, and thus help reduce the size and weight of the customer’s overall assembly. Wave springs also provide a true axial force; whereas the force from a coil spring can be skewed by the pitch of the coils. Axial space savings of 50% are not uncommon since the crest-to-crest wave spring can operate at a much lower working height, and consequently within a smaller spring cavity.
An interesting aspect of wave springs is how their performance changes over time in static applications. Typically, a spring’s performance will not change over time in a static application. However, if a spring is being compressed close to solid or is operating at elevated temperatures than it could experience some deformation or load loss. In these cases it is important to factor the environment where the spring operates into the selection process to ensure optimum performance.
In general, compressing a wave spring below the specified work height is not recommended. As a wave spring travels closer to its solid height, the loads increase exponentially, and the loading can then become unpredictable. This increased deflection can also overstress the material causing the spring to relax and take a set. The amount of relaxation will be different for each design, so if your application requires the spring to be compressed below the working height, either during operation or perhaps as part of the assembly process then again this needs to be factored in during the design process. The springs can then be pre-set as part of our manufacturing process to stabilise the part and ensure a consistent operational performance.
When specifying a wave spring, the range between the free height and the solid height is defined by the available deflection. The free height is approximate and can be adjusted for each batch to ensure load requirements are met, therefore the spring rate and available deflection are only ever for reference. In many cases the wave springs will work at other heights, however TFC recommends contacting its technical team to discuss the application, who will evaluate the theoretical spring characteristics and thus the suitability for the application.
Wave springs meet the needs of a wide range of applications to exert a force where light to medium loads are required. In addition, however by virtue of the many alternative types of Smalley wave springs now available, and utilising different design options, they can also be used where dynamic performance or much higher forces are required.
Wave springs are specified extensively within the automotive, petrochemical, aerospace, medical, motorsport and off-highway industries.
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