Glass-Filled PTFE Seal — why this filler for this component
For a seal, glass filling solves the problem that defines PTFE sealing: relaxation. An unfilled PTFE seal loses contact force over time as the polymer creeps, and a joint that was tight at assembly slowly weeps. Glass fibre holds that sealing force.
Where Glass-Filled PTFE Seal is used
Against a bronze-filled seal
glass keeps PTFE’s chemical resistance largely intact and is the correct choice for aggressive media. Bronze resists extrusion better at high pressure and removes heat faster, so it wins on hard hydraulic duty.
End of life is loss of sealing force or scoring of the counterface, whichever comes first. Inspect the mating surface at every seal change, because a scored bore will destroy the replacement quickly.
Key properties
Compound
Glass-Filled PTFE, typically 15% or 25% glass fibre
How it works here
The reinforcement resists cold flow, so the interference designed into the seal is still doing work months later. That is why glass-filled compounds appear so often in static and slow-cycling seals where the assembly is expected to stay closed without retightening.
Where it does not belong
Friction rises against unfilled PTFE, which matters for a dynamic seal, and the fibres abrade soft counterfaces. On an aluminium or plated bore a glass-filled seal will damage the surface it runs against.
Specifications
| Property | Value |
|---|---|
| Compound | Glass-filled PTFE, typically 15% or 25% glass fibre |
| Duty | Static and slow-cycling sealing, chemically aggressive media |
| Form supplied | Machined to seal drawing |
| Governing factor | Retention of sealing force against creep |
| Counterface | Hardened steel; avoid aluminium, brass and thin plating |
| Not suitable for | Hydrofluoric acid, strong alkali |
Manufacturing process
Compression moulded from 15% or 25% glass fibre compound, sintered, then machined to your drawing. Filled compounds need higher compaction pressure than unfilled PTFE to reach full density through the section.
Material selection notes
The reinforcement resists cold flow, so the interference designed into the seal is still doing work months later. That is why glass-filled compounds appear so often in static and slow-cycling seals where the assembly is expected to stay closed without retightening.
How to specify your order
Against a bronze-filled seal: glass keeps PTFE’s chemical resistance largely intact and is the correct choice for aggressive media. Bronze resists extrusion better at high pressure and removes heat faster, so it wins on hard hydraulic duty.
Quality checks and inspection
Dimensions are verified on CMM against your drawing. Filler content and sintered density are checked per ASTM D792, with tensile and elongation per ASTM D4894. A mill test certificate stating the lot, filler content and measured values ships with the order.
Ordering and export documentation
Confirm the counterface material before fitting. Mating faces must be clean — a trapped particle under a stiff filled seal initiates a leak path that will not self-heal the way a softer material might.
Export packing and lead time
HEMSUN is a DGFT IEC registered exporter (Government of India). Commercial invoice, packing list and certificate of origin accompany international despatch.
Storage and handling
End of life is loss of sealing force or scoring of the counterface, whichever comes first. Inspect the mating surface at every seal change, because a scored bore will destroy the replacement quickly.
Compliance & Standards
HEMSUN is a DGFT IEC registered exporter (Government of India). Filler content and sintered density are verified per ASTM D792 on each batch, with tensile and elongation checked per ASTM D4894.
Frequently Asked Questions
What Glass-Filled PTFE Seal options does HEMSUN manufacture?
For a seal, glass filling solves the problem that defines PTFE sealing: relaxation. An unfilled PTFE seal loses contact force over time as the polymer creeps, and a joint that was tight at assembly slowly weeps. Glass f…
Can you supply Glass-Filled PTFE Seal for OEM and export orders?
Yes. We support prototype lots, recurring OEM programmes, and export packing with material certificates and dimensional inspection reports on request. Typical RFQ response is within one business day when drawings are complete.
How do I request a quote for Glass-Filled PTFE Seal?
Send material grade, dimensions or drawing, quantity, application media, and operating temperature/pressure via https://hemsun.com/contact. Our engineering team confirms manufacturability, lead time, and pricing.
