What is the purpose of a sealing ring?

Core Functions of Sealing Rings

1. Physical Isolation Barrier
Blocking External Contaminants: Prevents dust, moisture, and chemical corrosives from invading equipment (e.g., preventing iron oxide powder from penetrating a magnetic encoder in a steel rolling mill).
Internal Media Sealing: Prevents lubricating oil, hydraulic oil, and coolant from leaking through gaps between moving parts (e.g., preventing grease spillage in a reducer shaft seal).

2. Dynamic Motion Sealing
Rotating Shaft Sealing: The lip of a skeleton oil seal adheres tightly to the shaft, maintaining a seal as the shaft rotates (e.g., protecting motor bearings from dust and water).
Reciprocating Motion Sealing: A shim seal/U-ring maintains a sealed oil chamber during hydraulic cylinder piston rod extension and retraction (e.g., the injection molding machine's shot-shooting cylinder).

3. Pressure System Maintenance
Pressure-Burst Prevention: O-rings deform under pressure to fill grooves and withstand high hydraulic system pressures (e.g., valve block seals ≥30 MPa in construction machinery).
Vacuum Environment Sealing: Elastomers expand to fill micro-gaps, maintaining negative pressure in vacuum chambers (e.g., semiconductor coating equipment). 

4. Mechanical Protection
Anti-metal seizure: Isolates contact between the inner and outer rings of the bearing and the housing, preventing fretting corrosion (e.g., wind turbine gearbox bearing seats).
Vibration Cushion: Absorbs high-frequency vibrations in the equipment and protects precision components (e.g., servo encoder mounting flanges).

5. Safety Protection
Prevents harmful media leakage: Corrosion-resistant materials (e.g., FKM fluororubber) prevent acid/solvent leakage (e.g., chemical pump seals).
Flame-retardant and explosion-proof: Specially formulated rubber rings block the transmission path of flammable gases (e.g., explosion-proof motor junction boxes).

6. Friction Control Optimization
Lubrication Retention: Lip seals store grease, reducing the coefficient of rotational friction (e.g., automotive wheel hub bearing seals).
Reduced Dry Friction: PTFE seals are inherently lubricating, extending the life of reciprocating components (e.g., air compressor piston rings).