Machined plastic parts
Machined PTFE parts
Machined PTFE parts are seats, bushings, backup rings, seal jackets, spacers and insulators cut from PTFE rod, tube or sheet: the resin is formed into those stock shapes and the finished part is machined from them [S1, S2, S3]. Conquest Seal supplies custom PTFE parts in virgin PTFE and in glass, carbon or graphite, bronze and MoS2 filled grades, machined to your print by the shops we source from. A certificate of conformance ships with every order, and the resin maker's certificate is available on request. Send the drawing, the grade and the quantity, and a Conquest representative replies with the quote.
- Grades
- Virgin or filledglass, carbon or graphite, bronze, MoS2
- Stock shapes
- Rod, tube, sheetASTM D1710 and ASTM D3294
- Paperwork
- Certificate of conformancewith every order; resin certificate on request
- Supplied
- Machined to your printby the shops we source from
How PTFE machining works
PTFE machining starts from semi-finished stock, not from a mold. The resin powder, plain or blended with a filler, is pressed into a preform and sintered in an oven, or ram-extruded into continuous rod and tube, and the finished part is machined from that stock [S1]. ASTM D1710 covers extruded PTFE rod, heavy-walled tubing and basic shapes, and ASTM D3294 covers molded PTFE sheet and molded basic shapes [S2, S3]. That is why a PTFE seat or bushing is quoted from a drawing and a stock size, with no mold to build.
The material earns the machining cost with three properties. It is inert to almost every industrial chemical and solvent, with a short list of exceptions such as the alkali metals and fluorine; it runs dry with very low friction and little stick-slip; and it is a strong electrical insulator [S1]. Its weakness is mechanical: under a constant load virgin PTFE slowly cold-flows out of shape, it springs back very little, and it does not last long in wear, which is why fillers exist [S1].
The five PTFE grades and what each filler changes
Conquest Seal supplies machined parts in five PTFE grades: virgin, and glass, carbon or graphite, bronze and MoS2 filled. Fillers were added to PTFE to cut its creep and wear, and each one trades a little of the virgin resin's chemistry or insulation for strength [S1]. The table sets out what each filler changes as the resin maker Daikin Industries and the seal maker Parker describe it; where the print says only PTFE, the part is quoted in virgin resin.
| Grade | What the filler changes | Where it is usually specified | Watch for |
|---|---|---|---|
| Virgin (unfilled) PTFE | Nothing is added, so the part keeps the resin's full chemical inertness, low friction and electrical insulation | Seats and seals in aggressive chemistry at a light load; insulators and spacers | Cold flow under a steady load, little spring-back and a short wear life |
| Glass filled | Less creep at low and high temperature, longer wear life and more compressive strength, with little change to the electrical properties; Daikin lists wear, chemical and mechanical resistance for its glass grades | Seats, rings and seals that must hold their shape in chemical service; Daikin lists oil sealing | Hydrofluoric acid and strong bases attack the glass; Daikin advises against glass grades where the mating part is a soft metal, except at a very low glass loading, and notes uneven wear in water |
| Carbon or carbon-graphite filled | Harder, with less creep and better heat transfer; adding graphite lowers wear, and Daikin lists carbon with graphite for low wear at high speed | Dry-running and pneumatic seals, bushings and wear rings; Daikin lists its hard-carbon grade for water service at medium and high loads | Slightly conductive; in oxidizing media a glass grade does better |
| Bronze filled | Resists deformation and extrusion under load, and conducts heat and electricity better; Daikin lists compression resistance | Hydraulic rod and piston seals and heavily loaded parts; Daikin lists its bronze grade for hydraulic and pneumatic systems | Bronze is a copper-tin alloy that some chemicals attack, and Daikin advises against its bronze grade for water service or for parts that must insulate; oxidation can darken the part without affecting its quality |
| MoS2 filled | Harder and stiffer, with lower friction and little electrical effect | A small share beside another filler, usually glass; Daikin lists a bronze, glass fiber and MoS2 blend for wear, compression and creep resistance in hydraulic cylinders | Strong oxidizing acids dissolve MoS2 |
PTFE in food contact: 21 CFR 177.1550
FDA regulation 21 CFR 177.1550 identifies the perfluorocarbon resins, PTFE among them, that may be used in articles intended to contact food, provided the resin meets the section's identity, specification and extractives requirements [S5]. The regulation covers the resin, and whether a grade complies is the resin or compound maker's statement. A filled grade adds a second test: the section allows other substances only as optional components that are themselves generally recognized as safe, prior-sanctioned or authorized under the food additive regulations [S5]. So a food-contact part is quoted on the maker's compliance statement for the exact grade; say on the request that the part touches food. The right wording is FDA compliant, never FDA approved.
Typical machined PTFE parts
Machined PTFE parts in a sealing system usually fall into five groups. Each entry below names the part, the grade usually on the print, and the page that goes deeper where one exists.
- Valve seats and seat inserts. Virgin PTFE where the medium is aggressive and the load is light; a filled grade where the seat must hold its shape under closing force.
- Bushings and bearings. Filled grades, because the filler is what gives PTFE its wear life; carbon-graphite where the part runs dry.
- Backup rings. Solid, split and spiral rings that stop an O-ring extruding under pressure; the standard families are on the backup rings page, and a ring for a nonstandard groove is machined to the print.
- Spring-energized seal jackets. The U-shaped PTFE jacket that carries the spring, virgin for chemistry and filled for wear; see spring-energized PTFE seals.
- Insulators and spacers. Virgin PTFE for its electrical insulation and chemical inertness, in washers, bushings and standoffs machined to the drawing.
A machined part or a standard seal
Not every PTFE sealing job needs a drawing. A solid or filled PTFE O-ring comes in AS568 sizes, a PTFE-encapsulated O-ring puts a fluoropolymer jacket over a rubber core for a groove built for rubber, and spring-energized seals are made to the hardware from the maker's range. A machined part is the answer when the shape is your own: a seat, a stepped bushing, a nonstandard ring or an insulator. Flat PTFE gaskets are a different route again; they are cut from PTFE sheet or filled PTFE sheet on our waterjet.
What to send for a quote
A machined PTFE part is quoted from the drawing, so the more of this the request carries, the fewer questions come back. Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
- The drawing. A STEP file for the shape and a PDF for the dimensions and tolerances is the ideal pair; state the temperature the dimensions apply at, because PTFE grows with heat.
- The grade. Virgin, or the filler and its share (for example glass filled or bronze filled), or the compound maker's grade number if the print names one.
- The stock callout, if any. ASTM D1710 covers extruded PTFE rod, heavy-walled tubing and basic shapes [S2]; ASTM D3294 covers molded PTFE sheet and molded basic shapes [S3].
- The quantity. The order quantity now, and the annual usage if the part repeats.
- The service. The medium, the temperature, the pressure and whether the part moves, so the grade on the print can be checked against the job.
- The paperwork. A certificate of conformance ships with every order; say if the program also needs the resin maker's certificate or, for a food-contact part, the maker's compliance statement for the grade.
Related pages
Frequently asked
Does Conquest Seal machine PTFE parts itself?
No. PTFE parts are machined to your print by the shops we source from, and Conquest Seal supplies them with the certification your order calls for. The parts Conquest cuts on its own waterjet are flat sheet gaskets.
Is PTFE the same as Teflon®?
Teflon is the Chemours brand for its fluoropolymer resins, PTFE among them. A print that says Teflon almost always means PTFE, and it is quoted as PTFE unless the drawing requires that maker's resin.
Why would a part need filled PTFE instead of virgin?
Virgin PTFE creeps under a steady load and wears quickly. A filler such as glass, carbon or bronze holds the part's shape and extends its wear life, at some cost in chemical resistance or electrical insulation.
Which filled grade goes on the print?
The one the duty points to: glass for creep resistance in chemical service away from hydrofluoric acid and strong bases, carbon or carbon-graphite for dry-running and pneumatic parts, bronze for hydraulic seals and heavily loaded parts, and MoS2 alongside another filler for lower friction. The compound sheet for the grade settles the detail.
Is machined PTFE FDA compliant?
Virgin PTFE resin can comply with 21 CFR 177.1550, the FDA regulation for perfluorocarbon resins in food contact, when the maker's grade meets its requirements. A filled grade qualifies only if its filler is permitted too, so the quote follows the maker's statement for the exact grade.
What stock shapes are PTFE parts machined from?
Rod, tube and sheet: extruded rod and heavy-walled tube to ASTM D1710, and molded sheet and basic shapes to ASTM D3294. The size and shape of the part decide which stock it is machined from.
What tolerances can a machined PTFE part hold?
The shops quote to the tolerances on your print, and no figure is published here. PTFE expands with heat and creeps under load, so put the measuring temperature on the drawing; if a feature is tighter than the material can hold, the quote says so before parts are made.
Can you supply spring-energized seals and backup rings as well?
Yes. Spring-energized PTFE seals are supplied from the makers to your hardware, and PTFE backup rings come in the standard families and in solid, split and spiral styles.
Related guides
Sources
- [S1] Parker PTFE Seals Design Guide, PDE 3354 GB, 02/2015, sections 1.1 to 1.3, read 2026-09-25.
- [S2] ASTM D1710: Standard Specification for Extruded Polytetrafluoroethylene (PTFE) Rod, Heavy Walled Tubing and Basic Shapes, D1710-15(2021), read 2026-09-25.
- [S3] ASTM D3294: Standard Specification for Polytetrafluoroethylene (PTFE) Resin Molded Sheet and Molded Basic Shapes, D3294-15, read 2026-09-25.
- [S4] Daikin Industries, PTFE Compound-Series product page, read 2026-09-27.
- [S5] 21 CFR 177.1550: Perfluorocarbon resins, US Food and Drug Administration, eCFR, amended through 2016-11-22, read 2026-09-27.
Material properties are stated in our own words from the sources above; no standard's text or table is reproduced.
Teflon is a trademark of The Chemours Company FC, LLC. No affiliation or endorsement is implied.
Send the PTFE part drawing
A STEP or PDF drawing, the grade (virgin or the filler), the quantity, and the medium, temperature and pressure the part sees. The part is machined to your print by the shops we source from; a Conquest representative replies with the quote.
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