SKF
Principles of Sealing Selection and Application (Power Transmission)
Selecting the correct power transmission seal requires analysing the shaft speed (peripheral velocity), lubricant type and viscosity, operating temperature, pressure across the seal, shaft surface finish and hardness, and the type and concentration of environmental contaminants. SKF’s principles of sealing selection provide a structured methodology: choose the seal design (single lip, double lip, with or without spring), select the material based on temperature and fluid compatibility tables, and verify the application parameters such as dynamic runout, misalignment, and housing bore finish. Following these principles prevents common failure modes — such as overheating, lip hardening, and leakage — and ensures the seal achieves its full potential service life.
Send an Enquiry
We'll get back to you on WhatsApp.
Trusted by Industry Leaders
Fluid Type First
Mineral oil, synthetic, and water‑based lubricants demand different elastomers.
Peripheral Speed Rating
Limits in m/s for each lip material and design.
Pressure Differential Management
Standard seals tolerate ~0.5 bar; higher pressures need special designs.
Shaft Hardness and Finish Defined
45‑60 HRC, Ra 0.2‑0.8 µm.
Dynamic Runout Tolerance
Maximum permissible shaft whip for lip follow.
Housing Bore Tolerance
Maintaining correct static sealing force.
The Seal as a Tribological System
The lip, shaft, and lubricant form a three‑body system. The oil film between the lip and shaft must be thin enough to prevent leakage, yet thick enough to prevent wear. SKF’s principles quantify this film thickness and the required contact pressure. Designing outside these bounds — too rough a shaft or too viscous an oil — tips the balance into leakage or lip burn.
Common Misinterpretation: A Seal Is Not a Bearing
A radial shaft seal cannot support radial load. If the shaft is misaligned or the housing bore is eccentric beyond the seal’s tolerance, the lip cannot follow, and it leaks. SKF’s principles clearly separate the functions of bearing (load support) and seal (fluid retention), and demand that shaft guidance be provided solely by the bearing.