Explain the design of a 'Tapered Mandrel' for the high-speed automated installation of external spiral retaining rings.

Automated installation requires a tapered mandrel and a plunger. The mandrel's base diameter should match the shaft diameter, and the taper angle should be shallow (typically $3°$-$5°$) to minimize the force required and the stress on the ring. The ring is pushed up the taper, expanding it gradually. The surface of the mandrel must be hardened (HRC $60+$) and polished to a mirror finish to prevent galling of the ring's ID. If the mandrel is too steep, the ring may 'flip' or undergo uneven expansion, leading to permanent deformation or 'cork-screwing,' where the turns of a multi-turn ring separate permanently.