Official Answer
Answer
The 'Retained Part' is the component the ring is holding in place. If this part has a large corner radius $R$ or a large chamfer, it will contact the retaining ring further away from the groove. This increases the moment arm $l = R + (t/2)$, which increases the bending stress on the ring and the likelihood of the ring 'dishing' or walking out of the groove. To maximize capacity, the retained part should have a 'Square Corner' (maximum $0.005$ inch radius). If a large radius is unavoidable, a hardened 'Backing Washer' with a square corner must be placed between the part and the retaining ring to distribute the load back toward the groove support.
