1. Chrome plating on the surface to improve wear resistance;
2. Loose holes are plated with chromium to improve surface oil storage and speed up running-in;
3. Engraved on the inner surface to improve elasticity;
4. An oil storage groove is provided on the outer surface of the ring to facilitate lubrication;
5. The outer surface of the ring is plated with copper to facilitate running-in;
6. Molybdenum is sprayed on the outer surface of the ring to reduce adhesion and wear.

Summarized as follows:
Improve wear resistance: chrome plating, nitriding
Improve initial running-in performance: copper plating, phosphating, sulphurizing
To prevent adhesive wear: spray molybdenum