Ask the Expert - Retaining Ring Design and Wave Spring Performance in Extreme Temperatures

It's time to answer commonly asked retaining ring and wave spring design questions through the one and only, Ask the Expert Blog. This week, our experts talk about retaining ring design and wave spring performance in extreme temperatures.

What is the ideal groove corner radius to balance retaining ring fit versus stress risers?

The recommended groove corner radius for a retaining ring with a diameter of 1 in. and under is .005 in. maximum. For a retaining ring with a diameter larger than 1 in., it is .010 in. maximum. 
For any other groove radius, please consult Smalley Engineering to determine its effectiveness.  

How much material is recommended between the end of my housing or shaft and the groove?

As a general rule, the distance from the end of the housing or shaft to the groove wall should be approximately three times the groove depth. However, each application may have more specific requirements that could allow for a shorter distance or require the groove to be located futher down the housing or shaft. 

View detailed calculations for edge margin

How do wave springs hold up to cryogenic temperatures?  Will the spring rate change and are some materials you offer better suited for these colder temperatures?

The spring rate increases when springs are subjected to cryogenic temperatures; however, the increase is minimal. The modulus of elasticity for almost all steels only increases slightly from room temperature to cryogenic temperatures, and in turn, the spring rate is minimally affected.

Not all types of steel are suited for cryogenic conditions. Certain alloys become brittle at very cold temperatures and are not a good choice for a spring operating in cryogenic conditions. Some alloys that Smalley customers have had success with are 302, 316, A-286, Inconel and Elgiloy. These alloys are successful because they retain their microstructure in extremely cold temperatures. Copper alloys such as beryllium copper and phosphor bronze can also work well for these applications. 

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