Rubber Seals
O-Rings
An O-ring is the cheapest part in most assemblies and the most common cause of a warranty return.
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Solution
Seal Material Selection Across Twelve Compounds
Most seal failures that reach a purchasing desk are material decisions made earlier by somebody without the data. We hold twelve compounds and no incentive to push one of them, which is the only way this advice is worth anything.
Stage by Stage
Where It Usually Goes Wrong and What We Do Instead
Each stage lists the failure mode first, then how we close it. If a stage does not apply to your part we will say so rather than bill for it.
Define the Medium
A seal specified only as rubber will meet a fluid nobody told the moulder about.
We start from the actual fluids, including cleaning agents and occasional exposure, not just the primary medium.
Define the Temperature
Continuous temperature is quoted but the peak and the cold start are not, and the seal fails at the extreme.
We ask for continuous, peak and minimum temperature, because the low end often rules out the obvious compound.
Define the Movement
A dynamic seal specified as if it were static wears out early.
We separate static face and bore sealing from reciprocating and rotary duty, which changes both compound and profile.
Shortlist Compounds
Buyers are given one option and no reasoning.
We shortlist from FKM, FFKM, SIR, EPDM, NBR, SBR, FVMQ, AEM/ACM, HNBR, CR, NR and CSM, and say what each one gives up.
Check the Size Route
A standard size gets tooled unnecessarily, or a non standard size gets substituted with the nearest stock item.
Standard imperial sizes run from our complete AS568 mould set. Non standard sizes get a tool rather than a substitution.
Prove It
A material decision made on a datasheet is not the same as one proven in the assembly.
We supply samples for your own fit and function check before you commit to a production quantity.
Products From This Process
Rubber Seals
AS568 O-Ring Series
We possess all the moulds for the AS568 O-ring size range, which lets us supply standard parts of the series promptly and without a tooling step.
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Rubber Seals
NBR O-Rings
NBR is the working compound for anything that meets oil or fuel at moderate temperature.
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Rubber Seals
EPDM Seals and EPDM O-Rings
EPDM has good weather resistance and unusual versatility, which is why it appears across automotive, electrical and electronic products, daily necessities, sports equipment and mechanised industrial equipment, as well as in wires, cables and high voltage and ultra high voltage insulation materials.
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Seal Material Selection Across Twelve Compounds Questions
Which compound resists oil and fuel best at reasonable cost?
NBR is the usual answer for oil and fuel resistance at moderate cost. Where temperature or chemistry goes beyond it, FKM is the next step.
Which compound is best for water heating and weather exposure?
EPDM, because of its heat, ozone and weather resistance. It is the wrong choice where mineral oil is present.
What do I send you to get a recommendation?
The medium, the continuous and peak temperature, the pressure, whether the seal moves, and the size or drawing.
Do you charge for material advice?
No. It is part of quoting the part properly.
Can I get samples before committing?
Yes. Ask for samples with the quotation.
Start With the Drawing
Send what you have, even if it is only a sample photo and a quantity. We will tell you what else we need.