Factors Affecting the Sealing Performance of Skeleton Oil Seals
1. Influence of Assembly
During the assembly of skeleton oil seals, the oil seal seat's mating end face must have a 15–30° chamfer, a bottom fillet radius of R ≤ 0.5 mm, and no damage to the seat hole.
2. Influence of Axial and Radial Shaft Movement
Axial movement increases in high-speed rotating shafts due to gaps. For example, improper adjustment of a reduction gearbox's primary shaft can lead to excessive movement, accelerating lip wear under high-speed operation.
3. Influence of Temperature
Temperature fluctuations cause oil seals and skeletons to expand or contract. Since metal and rubber have different thermal expansion coefficients, their expansion rates vary at a given temperature. Most skeleton oil seals use spring coils, which are made of fine metal and exhibit significant linear expansion under heat. This elongation reduces spring tension, leading to insufficient lip pressure and potential leakage.
4. Lip Interference
Interference refers to the difference between the free-state lip and shaft diameters. Proper interference generates radial force, compensating for shaft eccentricity. However:
Too little interference reduces sealing performance.
Too much interference causes the lip to clamp the shaft excessively, breaking the friction surface's oil film. During high-speed rotation, this raises lip-shaft temperatures, accelerating lip aging, cracking, or even burning, resulting in seal failure.
5. Influence of Material Selection, Structural Design, and Manufacturing Errors
Common rubber materials for seals include:
Nitrile rubber (NBR)
Ethylene propylene diene monomer rubber (EPDM)
Silicone rubber (VMQ)
Fluororubber (FKM/FPM)
Chloroprene rubber (CR)
These materials vary in properties (temperature resistance, chemical compatibility, hardness, compression set, and wear resistance). Selection must account for application-specific conditions.