The cornerstones of seal design: key design elements of rubber seals

Rubber seals play a vital role in the design of machinery and equipment. Their effective design and optimization directly affect the sealing performance and service life of the system. The following are the key elements of rubber seal design:

1. Material selection

Material types:

Natural rubber (NR): has good elasticity and wear resistance, but poor oil resistance, suitable for general working conditions.

Nitrile rubber (NBR): good oil and solvent resistance, suitable for petrochemical industry.

Fluororubber (FKM): high temperature resistance, chemical corrosion resistance, suitable for extreme environments.

Silicone rubber (VMQ): excellent high temperature and low temperature resistance, suitable for high and low temperature changes.

Hydrogenated nitrile rubber (HNBR): comprehensive high performance, wear resistance, oil resistance, high temperature resistance.

Material performance evaluation:

Wear resistance: evaluate the wear of materials under friction conditions, using tools such as hardness tester and friction coefficient tester for testing.

Corrosion resistance: evaluate the corrosion resistance of materials through immersion tests (such as sulfuric acid, hydrochloric acid, alkali solution, etc.).

Temperature resistance: test the physical properties of materials at different temperatures, such as elasticity and tensile strength.

2. Geometry and size

Seal type:

O-ring: the most common seal, suitable for static sealing and low-pressure dynamic sealing.

U-ring: suitable for high-pressure and high-temperature environments, providing stronger sealing ability.

X-ring: has a double-layer sealing structure, suitable for occasions requiring high sealing.

D-ring: suitable for sealing large-diameter shafts, providing better fit.

Dimension design:

Nominal diameter: select the appropriate inner and outer diameters of the seal to ensure its flexibility in the installation groove.

Sectional diameter: the selection of section diameter directly affects the sealing performance and service life of the seal.

Tolerance range: strict dimensional tolerance control to ensure a close fit between the seal and the sealing groove.

3. Installation environment and process

Installation groove design:

Groove width and groove depth: design a mounting groove that meets standard requirements to ensure that the seal can be fully expanded in the groove.

Groove shape and groove bottom: the groove bottom should be smooth to avoid uneven local force on the seal.

Installation process:

Pre-compression amount: Determine the appropriate pre-compression amount according to the seal type and working pressure to ensure the sealing effect.

Lubrication and cleaning: Use appropriate lubricants before installation and ensure the cleanliness of the installation environment to avoid impurities affecting the sealing performance.

4. Performance testing and verification

Performance testing:

Compression permanent deformation: Test the deformation recovery ability of the seal under high pressure environment.

Low temperature performance: Test the performance change of the seal after cooling to a specific temperature.

High temperature performance: Test the performance retention ability of the seal under heating conditions.

Verification method:

Dynamic test: Perform reciprocating motion in a simulated working environment to test the dynamic sealing performance of the seal.

Static test: Use a high-pressure sealing test bench to detect the leakage of the seal under static conditions.

Conclusion

The design of rubber seals includes multiple key elements, including material selection, geometry and size design, installation environment and process, performance testing and verification, etc. Reasonable selection and application of these elements can effectively improve the performance and service life of the seal and meet the sealing requirements under different working conditions. During the design process, all influencing factors should be considered comprehensively, and the product design should be continuously optimized through experiments and tests to ensure the reliability and efficiency of the seals.

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