Official Answer
Answer
Centrifugal lift-off occurs when the outward radial force $F_c = m r \omega^2$ on the ring exceeds the inward elastic 'clinch' force that holds the ring in the groove. When this happens, the ring expands, and a gap forms between the ring ID and the groove bottom. This is detected during high-speed testing if the assembly suddenly loses axial constraint or if the ring is found 'loose' on the shaft after a run. In some cases, the ring will show wear on its OD from rubbing against the stationary housing after it lifted off the shaft. The solution is either to increase the 'clinch' (design the ring with a smaller free diameter) or to use a self-locking spiral ring that prevents expansion via a mechanical tab.
