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When selecting an elastomer for seals, buyers often focus first on hardness, tensile strength, temperature resistance or oil resistance.
For O-rings, gaskets and other components that remain compressed for long periods, however, another property deserves attention:
compression set.
A sealing material may have good initial mechanical properties, but if it cannot recover sufficiently after prolonged compression, sealing performance may gradually be affected.
Compression set indicates how well an elastomer recovers after being compressed for a specified period under defined conditions.
For sealing components, recovery is important because the elastomer needs to maintain contact with the sealing surfaces.
This is why hardness and tensile strength alone are not enough to evaluate a material for long-term sealing.
O-rings, oil seals and gaskets depend on continuous contact pressure.
If an elastomer develops excessive permanent deformation after prolonged compression, its ability to maintain that contact can decrease.
Compression set therefore deserves particular attention in applications such as:
No.
The complete operating environment must also be considered.
Ask:
Compression set is one important selection criterion, not the only one.
If a sealing component requires compression recovery while also operating in contact with fuels, oils, solvents or demanding temperatures, a fluorosilicone compound may be worth evaluating.
KIMITER MY-FSR Low Compression Set Fluorosilicone Compound is available in several hardness grades, including 40, 50, 60 and 70 Shore A.
According to the product information, the series is designed for oil, solvent and chemical-media resistance and is used in aerospace, automotive and petrochemical sealing applications. The published operating-temperature range is -60°C to 200°C, while its listed compression-set specification is ≤10% under the stated test condition of 25% compression at 177°C for 22 hours.
For a more useful recommendation, provide:
The application conditions are usually more useful than simply asking for “a 60 Shore A fluorosilicone.”
For long-term compressed seals, lower compression set generally indicates better recovery under the specified test conditions. Other performance requirements must still be considered.
No. Material selection depends on the fluid, temperature, sealing requirements and other operating conditions.
Fluorosilicone materials can be evaluated when resistance to fuels, oils or certain solvents is required together with silicone-like temperature performance.
No. Two compounds with similar hardness may perform differently depending on the fluid, temperature and formulation.
Provide the current material specifications, hardness, operating fluid, temperature range, processing method and required finished-part tests for comparison.
Final material selection should be verified under the actual media, temperature, processing and finished-part test conditions.
