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Key Features of Sealing Rings
1. Basic Definition
A sealing ring is an annular elastic element that fits into the grooves between mechanical components, preventing gas, liquid, or dust from penetrating the equipment through the gaps.
2. Core Functions
Static Sealing: Fills fixed joints (such as end caps and housings) to prevent external contaminants from entering.
Dynamic Sealing: Maintains sealing performance in rotating/reciprocating parts (such as piston rods and shafts) while allowing component movement.
Pressure Maintenance: Withstands system pressure (such as hydraulic oil pressure) to prevent leakage.
Anti-Seizure Isolation: Isolates metal parts from direct contact to prevent frictional corrosion (such as bearing seals).
3. Typical Structural Types
| Sealing Ring Type | Structural Features | Primary Applications |
|---|---|---|
| O-Ring | Circular cross-section, solid elastomer | Static seals, low-pressure dynamic seals |
| Radial Lip Seal(Shaft Seal) | Metal casing + rubber sealing lip | Rotating shaft sealing(oil retention & dust exclusion) |
| U-Cup Seal | U-shaped profile with energizing spring | High-pressure hydraulic/pneumatic cylinders |
| Labyrinth Seal | Non-contact multi-stage baffle arrangement | Dust exclusion in rotating machinery(zero friction) |
4. Key Material Selection
Nitrile (NBR): Excellent oil resistance, low cost → General hydraulic/pneumatic systems.
Fluorocarbon (FKM): High-temperature/chemical resistance → Engine oil seals, chemical equipment.
Polyurethane (PU): Wear and extrusion resistance → High-pressure hydraulic cylinders.
Polytetrafluoroethylene (PTFE): Low friction and corrosion resistance → Food/pharmaceutical machinery.
Silicone (VMQ): Excellent elasticity retention → High-temperature sealing gaskets.
5. Failure Mode Warnings
Permanent deformation: Loss of elasticity due to high temperature or continuous compression → Seal failure.
Extrusion failure: Material squeezes into metal gaps under high pressure → Seal tearing.
Chemical corrosion: Swelling/cracking caused by media corrosion → Sealing function deterioration
Abrasive wear: Dust embedded in the sealing surface accelerates wear → dynamic seal leakage
6. Installation and Maintenance Key Points
Groove Accuracy: Dimensional tolerance ±0.05mm, roughness Ra ≤ 1.6μm
Surface Treatment: Chrome plating/polishing of contact surfaces to avoid scratching the seal ring
Lubrication and Protection: Apply silicone grease during assembly to prevent dry friction damage
Orientation Identification: Lip seals have an installation orientation (lip facing the sealing side).
