Official Answer
Answer
The thrust capacity of a retaining ring is calculated assuming a 'square-cornered' mating part. If the mating part has a large chamfer or radius, the load $P$ is applied further out on the ring's radial wall. This creates a large 'moment arm' that encourages the ring to 'dish' or tilt. The effective thrust capacity is reduced by a factor proportional to the size of the chamfer. Manufacturers provide 'Maximum Mating Part Radius and Chamfer' tables. If the chamfer exceeds these values, the ring may fail prematurely by being forced out of the groove due to the axial component of the force being converted into a radial 'camming' force.
