Official Answer
Answer
Spiral retaining rings are produced by coiling pre-tempered flat wire on its edge. This results in a circumferential grain flow that follows the curvature of the ring. Stamped snap rings are punched from flat sheet, meaning the grain flow is linear across the ring. The circumferential grain flow in spiral rings is superior for resisting radial cracks and provides higher fatigue strength and 'toughness' under impact. In a stamped ring, the grain ends are exposed on the edges, which can act as initiation points for cracks. Coiled rings also eliminate the 'burr' associated with stamping, reducing the risk of stress concentrations without requiring secondary deburring.
