TFC's engineers were faced with a problem when asked by one of its leading automotive electric motor OEM's to supply a 33mm external retaining ring capable of withstanding rotational speeds in excess of 17,000 rpm.

Conventional external retaining rings (circlips) are limited by centrifugal forces when the forces involved are sufficient to lift the ring out of the groove and, in this case, TFC's standard Spirolox® rings could only be considered suitable for rotational speeds of around 8,000 rpm.

The solution was found by supplying a special custom designed 'Self-Locking' ring that allowed the ring to function properly at higher rpm's. The self-locking feature utilises a small tab on the inside turn of the ring that locks into a corresponding slot on the outside turn. In addition to withstanding higher rotational speeds, the ring is also capable of sustaining vibration, functioning under rapid acceleration and absorb a degree of impact loading.


All of TFC's Smalley Spirolox® rings are manufactured using a unique edge-winding process which is as flexible as it is precise and accommodates design changes without the need for additional tooling or die modifications. This process facilitates the development of prototypes allowing the production of low quantity custom orders quickly and economically. Even after the initial prototypes are produced, the same process allows the design to be altered with simple machine adjustments or even a change of raw material size

For more information, visit www.tfc.eu.com.