Official Answer
Answer
Manual installation of spiral rings (especially multi-turn) involves 'walking' the ring into the groove, which can overstress the material if the ring is expanded too far. Automated winding tools use a plunger and a tapered sleeve (for bores) or a tapered mandrel (for shafts). The tool gradually and uniformly expands or contracts the ring as it moves axially. This prevents 'permanent set' by ensuring the material stress stays below the proportional limit $\sigma_p$. In high-volume automotive production, automated tools also provide 'error-proofing' (Poka-Yoke) by ensuring the ring is fully seated; sensors can detect the final axial position of the plunger, confirming that the ring has 'snapped' into the groove.
