- SHORE A
- ±5 pts against the specified hardness
- TENSILE
- Per compound datasheet, ASTM D412
Oil Seals · Made to order
FKM Rotary Shaft Seals — Heat, Fuel and Aggressive Chemistry
FKM rotary shaft seals for the shafts nothing else survives — to +250 °C, in fuels, hydrocarbons, hot oil and aggressive chemicals. Made to DIN 3760 and ISO 6194 sizes. Not for steam, hot water or glycol brake fluid — specify EPDM for those.
- HARDNESS
- 70–80 Shore A typical for a shaft-seal lip
- TEMPERATURE
- −20 to +250 °C standard grade. Upper figure is grade- and duration-dependent; −40 °C requires a low-temperature grade, quoted separately
- SIZE
- Shaft Ø × bore Ø × width, DIN 3760 / ISO 6194
- TYPE
- Type A plain lip or Type AS with dust lip
- GRADE
- Stated per application
- MADE TO ORDER
- ISO 9001:2015
- 09111526A
Product gallery
Visual Reference
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Cross section viewSection through lip, case and spring — on request
- Shaft diameter
- The first of the three ordering numbers
- Seal type
- DIN 3760 A or AS
- Medium
- Names the grade
- Peak vs continuous temperature
- Both — FKM tolerates excursions well above its continuous rating, and that headroom is often what is being bought
- Shaft surface finish and speed
- Surface speed at the lip, not just rpm; recommended finish stated on the drawing
Section drawing available on request. Send shaft diameter, housing bore and width, the medium, and both the continuous and peak temperatures — or the old seal and what failed — and we will confirm grade, type and lip design for approval.
Technical specifications
Engineering Data
- Product Family
- Oil Seals
- Material
- FKM (fluoroelastomer)
- Hardness (Shore A)
- 70–80 Shore A typical for a lip
- Tensile Strength
- Per grade datasheet, ASTM D412
- Elongation at Break
- Per grade datasheet, ASTM D412
- Operating Temperature
- −20 to +250 °C standard; −40 °C low-temperature grade on request
- Compression Set
- ASTM D395 Method B
- Density
- Per grade datasheet
- Colour Options
- Black standard; brown and green are common FKM identifiers
- Lead Time
- Confirmed with the quotation, from approved drawing and approved sample
- FKM grade
- Specified per application — fluorine content, cure system, low-temperature or fuel-qualified
- Seal type
- DIN 3760 Type A or AS
- Size designation
- Shaft Ø × bore Ø × width
- Medium compatibility
- Fuels, hydrocarbons, hot oil, aggressive chemicals. Not steam, hot water, glycol brake fluid, ketones, esters or amines
- Max surface speed
- Stated per application
- Shaft surface finish
- Recommended range on the drawing
- Certifications
- ISO 9001:2015 — certificate 09111526A, valid to 21 February 2027
- Minimum Order
- 10,000 pieces per part number, per compound, or quoted against the part where geometry or tooling makes that unrealistic. Prototype and first-article lots sit outside the minimum.
Dimensional reference
- Shaft diameter
- The first of the three ordering numbers
- Seal type
- DIN 3760 A or AS
- Medium
- Names the grade
- Peak vs continuous temperature
- Both — FKM tolerates excursions well above its continuous rating, and that headroom is often what is being bought
- Shaft surface finish and speed
- Surface speed at the lip, not just rpm; recommended finish stated on the drawing
Available materials
Rubber Compound Options
Select the compound best suited to your operating environment and application requirements.
| Rank | Compound | Temperature | Why |
|---|---|---|---|
| THIS PAGE | FKM | −20 to +250 °C continuous to +200 °C | Fuels, hydrocarbons, hot oil, solvents and aggressive chemistry, at temperatures nothing else here reaches. Excellent compression set hot. 2–3× NBR |
| Leave FKM if… | the medium is steam, hot water or glycol brake fluid | — | Specify EPDM (−40/+140 °C). Standard bisphenol-cured FKM is poor in steam; peroxide-cured grades help, but EPDM is the right answer |
| Leave FKM if… | the medium is a ketone, ester or amine | — | Acetone and MEK swell FKM; amines degrade it. Specify EPDM, or FFKM where temperature rules EPDM out — at a large cost step above FKM |
| Leave FKM if… | service runs below about −20 °C | — | Standard FKM stiffens in the cold — worse than NBR. Specify a low-temperature FKM grade, or NBR/EPDM if the chemistry allows |
| Leave FKM if… | hot oil peaks at 120–160 °C | — | Specify AEM (−40/+160 °C) — between NBR’s ceiling and FKM’s price |
| Also available | NBR · silicone · neoprene · SBR · natural rubber | See the compound table | NBR is the standard oil-seal compound and the default answer where temperature does not demand more; the rest are available but are not first choices for a rotary lip seal |
Not sure? Send the medium, temperature and load
SERVICE CEILING
+250°C
FKM, grade dependent
Key advantages
Why Specifiers Choose Margo
You are paying for temperature
FKM costs two to three times NBR, and buys you +250 °C, fuels, hydrocarbons and solvents with low compression set hot. Below about +120 °C in plain oil, NBR does the same job — we will say so.
Four media that destroy it
Steam and hot water, glycol brake fluid, ketones, amines. FKM resists almost everything else, which is exactly why the exceptions have to be checked before you order.
Standard FKM is not a cold compound
It stiffens below about −20 °C — worse in the cold than NBR. If your shaft starts at −30 °C, you need a low-temperature grade, and it is a different specification and a different price.
“FKM” is a family, not a material
Fluorine content and cure system change what it survives — a biodiesel seal and a steam-adjacent seal are different grades. Tell us the medium and we specify the grade, rather than shipping the one we happen to mix.
Industries served
Global Applications
Automotive
Engine and transmission shafts, turbocharger-adjacent seals, fuel-system components
Heavy Industry
Hot gearbox and drive shafts, process plant handling hydrocarbons and solvents
Pumps & Valves
Chemical transfer and process pumps
Infrastructure
Hydraulic systems on hot-running site plant
Manufacturing process
From Compound to Certification
Material compounding
Polymer blending, additive integration and batch QC in our in-house lab. The FKM grade and cure system are set here, against your medium.
Mould Design & CNC
Mould design and CNC tool manufacture, in-house, held as a controlled record. The lip profile sets the sealing force.
Moulding and metal bonding
Elastomer moulded and bonded to the case in one operation. Rubber-to-metal bonding in-house.
Post-cure
FKM is oven post-cured to complete crosslinking and drive off cure by-products. Without it the compound does not reach its published temperature or compression-set performance. The step that makes the +250 °C real.
Quality inspection
Lip concentricity, bore and width to DIN 3760, plus hardness and batch sampling.
Export packaging
Industrial packing with documentation. Seals packed to protect the lip. ISPM-15 treated pallets where timber is used.
Quality assurance
Certified to International Standards
Every product leaves our facility with a documentation package — material test reports, dimensional inspection sheets and a certificate of conformance — giving traceability from raw material to finished part.
ISO 9001:2015 · Certificate 09111526A
Integral Certification Ltd · Valid to 21 February 2027
Scope: rubber moulded components — quality management, not a product approval
IATF 16949 — upgrade in progress, certification targeted by end 2026
ISO 14001 and ISO 45001 — targeted 2027
Seals are made to DIN 3760 and ISO 6194 dimensions. These are dimensional standards, not certifications.
Certification detailProduction metrics
- Since 2005
- In operation
- 60+
- Active clients
- 3–4 weeks from approved sample
- Avg. lead time
Downloads
Technical Documentation
Grade datasheets and dimensioned drawings are issued on request, under NDA where required. Tell us the medium and both temperatures — continuous and peak — and we will send the compatibility data for the grades that suit it.
Request FKM grade dataFAQ
Technical & Commercial Questions
Answers to the most common questions from engineering teams and procurement managers worldwide.
What is the minimum order quantity for this part?
We supply in bulk. The minimum run is 10,000 pieces per part number, per compound, or quoted against the part where geometry or tooling makes that unrealistic. Prototype and first-article lots sit outside the minimum.
Can you match a competitor specification or reverse-engineer an existing part?
Yes. Send the old seal, the medium and both temperatures. If the incumbent seal is FKM, tell us why it was chosen — often the answer is a peak the shaft only sees at shutdown, and sometimes AEM at half the price covers it.
What file formats do you accept for drawings?
PDF, DWG, DXF and STEP — but a drawing is often unnecessary. Shaft diameter, housing bore, width, type A or AS, plus the medium and both temperatures is a complete specification. Name the FKM grade if your drawing calls one out.
Do you provide material test reports with each shipment?
Yes. Material test reports, dimensional inspection sheets and a certificate of conformance ship with every consignment. Hardness, tensile to ASTM D412 and compression set to ASTM D395 Method B are tested in-house, with dimensions checked against DIN 3760. Post-cure is recorded on the batch record, since it is what makes the temperature rating real.
What are your payment and delivery terms for international orders?
TT and LC accepted, discussed per order. Ex-works Nashik or FOB Nhava Sheva. Commercial invoice, packing list and certificate of origin are issued with every consignment. Seals are packed to protect the sealing lip.
Same compound
Other parts we mould in the same compounds
Guides
Further Reading
FKM vs NBR: Which Rubber Is Right for Your Application?
Compares fluorocarbon and nitrile across temperature, chemical resistance and cost-in-use — FKM −20 to +250 °C, NBR −30 to +120 °C. FKM is the answer where temperature or aggressive media demand it; NBR is the answer everywhere else, and it costs a fraction as much.
Need this part quoted?
Send shaft diameter, housing bore and width — or the old seal. Tell us the medium and both temperatures, continuous and peak. We confirm grade, type and lip design — and say if something cheaper than FKM will do — then quote against your annual quantity. We respond within 48 hours.