Fluorine Rubber (FKM) Seal Technology Guide
Fluorine Rubber (FKM) Seal Technology Guide
Fluorocarbon elastomers combine excellent chemical resistance with high-temperature capability. This guide dives into the technology behind FKM seals, from polymer chemistry to processing and application engineering.
## Polymer Chemistry
– **Vinylidene fluoride (VDF)** and **hexafluoropropylene (HFP)** form the backbone of most FKMs.
– **Tetrafluoroethylene (TFE)** and **perfluoromethylvinyl ether (PMVE)** additions tailor low-temperature and chemical properties.
– Cure systems include **bisphenol**, **peroxide**, and **amine** types; each impacts compression set and chemical resistance.
## Processing Considerations
– Maintain clean mixing equipment to avoid contamination (silicone residues inhibit cure).
– Control compound temperature during milling/extrusion to prevent scorch.
– Use precision molds; FKM shrinkage averages 2–3 %.
– Post-cure at 230 °C to remove volatiles and stabilise properties.
– Apply cryogenic deflashing for complex geometries.
## Application Engineering
– Select hardness based on pressure and dynamic requirements.
– Use backup rings for high-pressure static seals.
– Control surface finish to ≤0.4 µm for dynamic applications.
– Consider filled FKMs (graphite, PTFE) to reduce friction.
– Evaluate compatibility with amines, steam, or organic acids when selecting grade.
## Testing & Validation
– Chemical compatibility (ASTM D471) in actual process fluids.
– Compression set and stress relaxation for longevity.
– Thermal aging (ASTM D573) to confirm high-temperature stability.
– Low-temperature flexibility tests when cold starts are expected.
– Explosive decompression testing (NORSOK M-710) for oil & gas service.
## Related Pages
– [FKM Material Guide](/materials/viton-fkm/)
– [High-Temperature Pressure Guide](/materials/fkm-high-temperature-pressure-rating-guide/)
– [Custom Manufacturing](/services/custom-manufacturing/) – tooling and production support.
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