Official Answer
Answer
The groove radius $R$ must be kept minimal (typically $R \le 0.005$ inches) to ensure the ring's flat surface makes maximum contact with the groove wall. If the radius is too large, it creates a 'ramp' that facilitates the ring dishing and eventually popping out under axial load. During assembly, the presence of a radius or a chamfer on the mating part also affects the load path. The calculation for the allowable load $P$ is derated based on the ratio of the radius to the ring thickness. Designers must specify 'square' grooves to maximize the efficiency of the spiral ring's multi-turn design.
