Answer
Spiral retaining rings are installed by spreading the turns and 'winding' them into the groove. The critical limit is the elastic strain of the material. The maximum installation diameter $D_{max}$ must not exceed the point where the fiber stress $\sigma = \frac{E t (D_{max} - D_{free})}{D_{max} D_{free}}$ exceeds the yield strength $\sigma_y$. For high-modulus materials like carbon steel, a tapered mandrel or a sleeve is used to ensure a uniform expansion. If the ring is over-expanded beyond its 'proportional limit', it will not return to its original diameter, resulting in a loose fit or 'rattle' in the groove. This is particularly dangerous in applications subjected to axial vibration, as the ring could oscillate and wear the groove walls.
