Official Answer
Answer
To achieve $360^{\circ}$ contact, the groove diameter $D_g$ must be precisely matched to the ring's design. For a shaft ring, the ring's free ID is always smaller than the groove diameter to ensure a 'cling' fit. The calculation is $D_{free} = D_g - (Cling)$, where 'Cling' is typically $1\%$ of the diameter. For a bore ring, the free OD is larger than the groove diameter. If the groove is too shallow, the ring will not fully expand/contract, leading to a gap in the $360^{\circ}$ support. This gap creates a localized stress concentration on the groove wall. Engineers must specify a groove width $W_g$ that is $10-20\%$ wider than the maximum ring thickness $T$ to allow for the 'winding' installation and axial movement.
