FFKM
also Chemraz, Perfluoroelastomer
FFKM is a fully fluorinated perfluoroelastomer (Kalrez, Chemraz) that combines PTFE-like chemical inertness and heat resistance with rubber elasticity, reaching about 17 MPa tensile strength, 140 % elongation and service to 300 °C.
Values for the Semiconductor Grade condition
FFKM grades and fills
FFKM is supplied in 7 conditions, soft to hard. Semiconductor Grade is the default FabDigit quotes; the values on this page are for it.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Low Temperature | Use where the seal must stay resilient below −20 °C while still needing full FFKM chemical resistance. | 14 | 170 | 75 Shore A | |
carbon-black filled, 70–75 Shore A | Lowest-cost workhorse FFKM for chemical process plant O-rings up to about 260–290 °C. | 15 | 160 | 72 Shore A | |
Plasma / Radical Resistant | Choose for direct exposure to NF₃/O₂/fluorine radical plasma chamber cleans where erosion rate and particle shedding dominate seal life. | 15 | 120 | 30 Shore D | |
High Temperature | Pick when the seal sees sustained >290 °C, e.g. ALD/CVD chamber, hot process gas or steam-hydrocarbon service. | 16 | 120 | 30 Shore D | |
Steam / Amine / Hot Water Resistant grade | Optimised cure system and filler for long-term hot water, saturated steam and amine service where standard peroxide-cured elastomers harden or blister. | 16 | 150 | 75 Shore A | |
Semiconductor GradeDefault low-particulate, plasma/wet-etch resistant perfluoroelastomer | Default choice for wafer-fab chamber, gate valve, slit-valve and wet-bench seals where particle generation, plasma erosion and metal-ion contamination matter. | 17 | 140 | 75 Shore A | |
RGD / Explosive-Decompression Resistant | Higher-hardness, high-modulus compound qualified against rapid gas decompression, H₂S/amine and sour well fluids in downhole and valve seals. | 21 | 110 | 40 Shore D |
Supply forms, finishes and certifications
Ways FFKM is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FDA-White | FDA / USP Class VI White | Certification |
What is FFKM?
FFKM is a fully fluorinated perfluoroelastomer (Kalrez, Chemraz) that combines PTFE-like chemical inertness and heat resistance with rubber elasticity, reaching about 17 MPa tensile strength, 140 % elongation and service to 300 °C. It is specified as net-shape molded O-rings and custom seals for semiconductor plasma and wet-process tools, chemical reactors and hot oilfield equipment where FKM swells or degrades. It is the highest-cost elastomer by a wide margin, lead times are long, and compounds are media-specific (Plasma, Steam-Amine, RGD, FDA-White); use FKM where its 200 °C limit and chemical range suffice. FFKM has a density of 2 g/cm³ (0.0723 lb/in³), heavier than 97% of polymer grades. Its glass-transition temperature is -3°C (27 °F). FFKM has a tensile strength of 17 MPa (2.47 ksi), weaker than 71% of polymer grades. Elongation at break is 140% and the elastic modulus is 0.01 GPa (0.0016 Msi).
What is FFKM used for?
- Semiconductor plasma chamber seals
- Wafer wet-process O-rings
- Chemical reactor and valve seals
- Hot oilfield downhole seals
- Steam and amine service gaskets
- Aerospace fuel and hydraulic seals
- Pharmaceutical process seals
Advantages
- High service temperature — 300°C (572 °F), better than 99% of polymer grades
- Good corrosion resistance — 98/100, better than 99% of polymer grades
- Good UV / weathering resistance — 95/100, better than 95% of polymer grades
Limitations
- High embodied carbon — 28 kg CO₂/kg, worse than 100% of polymer grades
- High mold shrinkage — 3.5%, worse than 98% of polymer grades
- Heavy — 2 g/cm³ (0.0723 lb/in³), worse than 97% of polymer grades
- Difficult to machine — 20/100, worse than 97% of polymer grades
- Low stiffness — 0.01 GPa (0.0016 Msi), worse than 80% of polymer grades
FFKM properties
Typical room-temperature values for FFKM-Semiconductor Grade; bars are the position among polymer grades.
Physical3
FFKM has a density of 2 g/cm³ (0.0723 lb/in³), heavier than 97% of polymer grades. Its glass-transition temperature is -3°C (27 °F).
Mechanical8
FFKM has a tensile strength of 17 MPa (2.47 ksi), weaker than 71% of polymer grades. Elongation at break is 140% and the elastic modulus is 0.01 GPa (0.0016 Msi).
Thermal8
FFKM is rated for continuous service to 300°C (572 °F). It conducts heat at 0.22 W/m·K (0.127 BTU/hr·ft·°F), better than 60% of polymer grades. Thermal expansion is 230 µm/m·K (127.8 µin/in·°F).
Electrical4
FFKM is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (98/100), better than 99% of polymer grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of FFKM takes about 400 MJ of energy and emits 28 kg of CO₂ — more than 100% of polymer grades. Typical recycled content is 0%.
Manufacturability3
FFKM's machinability is poor (20/100, worse than 97% of polymer grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. FFKM is highlighted; hover a dot for its name, or open the interactive family chart.
Working with FFKM
Is FFKM easy to machine?
Not a machining material — parts are net-shape moulded; trimming is done cryogenically or by waterjet, and any secondary cutting must avoid heat and tearing.
Can FFKM be welded?
Cannot be welded; joints are made by co-moulding or bonded splices, and spliced rings lose a large part of the burst/extrusion strength.
Can FFKM be formed, bent or molded?
Compression or injection moulded at roughly 170–205 °C with a long oven post-cure (up to ~305 °C, hours to days) to develop full compression-set and heat resistance; mould shrinkage is high (~3–4 %) so tooling must be scaled per compound.
Manufacturability
The process limits FabDigit applies to FFKM. Every FFKM part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
Injection molding
| Mold shrinkage | — |
|---|---|
| Wall thickness | — – — |
| Recommended draft | — |
| Pre-drying | — |
FFKM chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| tetrafluoroethylene (TFE)backbone comonomer, wt% of polymer | 50 – 70 | 62 |
| perfluoromethylvinyl ether (PMVE)flexibilising comonomer | 28 – 45 | 36 |
| cure-site monomer (e.g. perfluoro nitriltriazine or peroxide cross-link site | 0.3 – 3 | 1.5 |
| filler (carbon black, silica, TiO2, BaSOphr in the compound; grade dependent | 5 – 30 | 15 |
| curative / co-agent package | 0.5 – 4 | 2 |
What surface finishes work on FFKM?
Supplied as-moulded with minimal flash; semiconductor grades are washed/extracted and cleanroom packaged, and no coating or painting is practical on the low-energy fluorinated surface.
Surface treatments FabDigit runs on polymer parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Injection Molding Coating
Metallization / Functional
Equivalent designations
Standards and trade names that resolve to FFKM in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- ChemrazPerfluoroelastomerKalrez
How much does FFKM cost?
FFKM is a standard-cost polymer ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
FFKM — frequently asked
What is FFKM used for?
FFKM is typically used for semiconductor plasma chamber seals, wafer wet-process O-rings, chemical reactor and valve seals, hot oilfield downhole seals, steam and amine service gaskets and aerospace fuel and hydraulic seals. In short: semiconductor-grade perfluoroelastomer.
What is the tensile strength of FFKM?
FFKM has a typical tensile strength of 17 MPa (2.47 ksi) — weaker than 71% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is FFKM easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of polymer grades). Not a machining material — parts are net-shape moulded; trimming is done cryogenically or by waterjet, and any secondary cutting must avoid heat and tearing.
Can FFKM be welded?
Cannot be welded; joints are made by co-moulding or bonded splices, and spliced rings lose a large part of the burst/extrusion strength.
What surface finishes work on FFKM?
Supplied as-moulded with minimal flash; semiconductor grades are washed/extracted and cleanroom packaged, and no coating or painting is practical on the low-energy fluorinated surface.
Can FFKM be formed, bent or molded?
Compression or injection moulded at roughly 170–205 °C with a long oven post-cure (up to ~305 °C, hours to days) to develop full compression-set and heat resistance; mould shrinkage is high (~3–4 %) so tooling must be scaled per compound.
What is the maximum service temperature of FFKM?
FFKM is rated for continuous use to about 300°C (572 °F), and briefly to 340°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does FFKM cost?
FFKM is a standard-cost polymer ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in FFKM?
Yes — FFKM is available for injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- Kalrez Perfluoroelastomer Parts — product and compound selection data — DuPont (2023)
- Chemraz perfluoroelastomer compound datasheets — Greene Tweed (2022)
- ASTM D1418 / ASTM D2000 — rubber classification (FFKM) — ASTM (2022)
- ASTM D412 / D395 / D2240 — tensile, compression set, durometer hardness of elastomers — ASTM (2021)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics/Elastomers — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.