Sleeve: Without flat wire surface, the force is more evenly distributed; the material application is flexible. In the scene with large working load, 42CrMo is adopted, with greater tensile strength. In the scene with small working load, 20CrMo material is adopted, with stronger toughness and not easy to fracture.

Sleeve processing technology: blanking (sawing machine, pipe cutting machine) → chamfering at both ends (CNC lathe) → surface rough grinding (twice) (centerless grinder) → milling flat wire (milling machine) → heat treatment → surface finish grinding (twice) (centerless grinder).