Products
Machined plastic parts to your print
Some parts of a sealing system are machined from plastic rather than molded from rubber: seats, back-up rings, bushings, wear rings, spacers and insulators. Conquest Seal supplies them in PTFE, PEEK, UHMW, PFA, FEP, nylon and acetal, machined to your print by the shops we source from, with material certifications on request. They go where a rubber part would extrude, creep or simply wear out too quickly. Send a STEP, DXF or PDF drawing with the resin and the quantity and a Conquest representative quotes it.
- Materials
- PTFE, PEEK, UHMW, PFA, FEP, nylon, acetal
- Parts
- seats, back-up rings, bushings, wear rings, spacers, insulators
- Back-up rings
- PTFE, PTFE blends, polyamide or PEEK, per the published gland guides
- Back-up threshold
- about 725 psi to 1500 psi by source (Trelleborg, ERIKS, PAI); Parker® 800 / 1500 / 3000 psi for 70 / 80 / 90 Shore A
- Temperature ranges
- no approved resin range on file; the resin data sheet governs
- To quote
- send STEP, DXF or PDF, the resin and the quantity
Machined plastics fill the gaps rubber cannot: PTFE and PFA for chemical service, PEEK for heat and load, UHMW for wear, nylon and acetal for general parts. We source them from machine shops that hold the tolerances on your drawing, and material certifications are supplied on request. Every part is checked against the print before it ships. Tell us the material, the drawing and the quantity.
Whether you need a replacement part for equipment already running or a new part from your own drawing, send the print and we quote it.
Back-up rings and wear parts: where plastic takes over from rubber
An O-ring extrudes into the gap between piston and bore once pressure passes what its hardness can hold, and the published thresholds for adding a back-up ring run from about 725 psi to 1500 psi depending on the manufacturer: Trelleborg 725 psi for rings over 50 mm inside diameter and 1450 psi under it, ERIKS 750 psi for reciprocating service, PAI 1500 psi. Parker's rule of thumb by hardness is about 800 psi for 70 Shore A, 1500 psi for 80 and 3000 psi for 90 at a few thousandths of diametral clearance. The back-up ring materials those guides publish are PTFE and PTFE blends, 90 to 95 Shore A elastomers, or polyamide and PEEK for high temperature.
The same reasoning sends other parts to plastic: seats where an elastomer would swell, bushings and wear rings where rubber would tear, spacers and insulators where the part must hold a dimension or an electrical property. PTFE and PFA take the chemical service, PEEK the heat and load, UHMW the abrasion, nylon and acetal the general parts.
None of those resins carries an approved temperature range on this site, because no vendor-derived figure is on file, so the resin data sheet and your print govern and we quote to both. Every part is checked against the print before it ships, and material certifications ship with the parts on request.
Send a STEP, DXF or PDF drawing, the resin and the quantity, and we quote from the machine shops we source from.
Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Industries that buy machined plastic parts to your print
Frequently asked
What should the drawing state for a plastic part?
The resin and its grade, because PTFE alone covers virgin, glass-filled, carbon-filled and bronze-filled materials with very different wear and creep, and PEEK and nylon come unfilled and filled too. Add the tolerances with the temperature they are measured at, since plastics grow with heat and nylon also swells with moisture, and note any surface finish, color and certification the part needs. A STEP file for the shape and a PDF for the tolerances is the ideal pair.
When is PTFE, PEEK or UHMW the better material?
PTFE for chemical inertness and low friction, but it creeps under load and has no elastic recovery. PEEK for strength and stiffness at heat, in seats, back-up rings and bushings that a softer plastic would deform. UHMW for wear and impact in water and slurry, where it outlasts PTFE on abrasion but tops out at a lower temperature. Nylon and acetal cover general bushings, spacers and wear parts at everyday temperatures.
Do you supply PTFE back-up rings to a military or SAE part number?
Yes. The MS28774, MS28782 and MS27595 back-up ring families are now covered by SAE AS8791, and the rings come from manufacturers that make to that document; spiral, split and solid styles are all available. In the groove a back-up ring adds its own thickness to the groove width, with the ring on the low-pressure side of the O-ring, and two rings where pressure comes from both directions.
What tolerances are realistic on a plastic part?
Tighter than rubber, looser than metal, and always tied to temperature. Plastics expand far more than steel, PTFE creeps under sustained load, and nylon swells as it takes on moisture, so a tolerance is only meaningful with the measuring temperature and conditioning stated on the drawing. The shops we source from quote to the tolerances on your print; if a feature is tighter than the material can hold in service, the quote says so before the parts are made.
Can a plastic part replace a rubber seal that keeps failing?
In some jobs, yes. Where an O-ring extrudes, swells or runs dry, a PTFE or PEEK seat, back-up ring or wear ring takes the load the rubber cannot, and PTFE seals handle chemistry and dry running that elastomers do not. The trade is that PTFE has no elastic recovery, so a plastic seal needs a groove made for it or an elastomer energizer behind it, which is why many high-pressure and rotary seals are a plastic face with a rubber spring.
Related guides
Send a STEP, DXF or PDF drawing, the resin and the quantity
Plastic parts are machined to your print by the shops we source from, with material certifications on request. A Conquest representative replies with the quote.
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