Official Answer
Answer
Spiral retaining rings are more challenging to automate than stamped circlips because they lack holes for pneumatic pliers. Automation usually involves a plunger and a tapered cone. The ring is pushed down the cone, which gradually expands it (for external rings) or compresses it (for internal rings) until it snaps into the groove. This process requires precise control of the 'lead-in' angle (typically $15^\circ$ to $20^\circ$). Stamped rings are easier to pick-and-place, but spiral rings are preferred in automated aerospace assemblies because they have no 'ears' to interfere with other components in tight radial spaces.
