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Vespel · Polyimide

Highest-temperature plastic. Low outgassing. Aerospace bearings.

Q: Why is Vespel so expensive?

Vespel raw material: $500–800/kg (yes, eight hundred per kilogram). PEEK unfilled: $120–180/kg. Nylon: $8/kg. Vespel premium reflects: (1) Extreme difficulty of polyimide synthesis, (2) Specialty forming process (compression molded from powder, not injection molded), (3) Small production volumes globally. Use Vespel only when application genuinely requires its unique capabilities — the cost is usually justified by elimination of lubrication systems or enabling continuous high-temperature operation.

Q: Vespel vs PEEK — when is each right?

PEEK for: continuous service up to 260 °C, general high-performance plastic applications, medical implants (PEEK-OPTIMA), cost-justified performance. Vespel for: continuous service 260–300 °C, vacuum-critical applications (< 1% outgassing required), self-lubricating bearings where no maintenance is possible, aerospace hot-section components. Price: Vespel is 4–6× PEEK — the premium needs justification.

Q: How is Vespel formed?

Vespel is direct-formed or isostatic-pressed from polyimide powder, then sintered at ~400 °C. Not injection-moldable (polyimide doesn't melt below decomposition temperature). Available as cylindrical rods or billets for CNC machining. Custom near-net shapes available through DuPont for high-volume production applications.

Q: Machining Vespel — any special considerations?

Yes. Vespel is abrasive (graphite filler wears tools), dimensionally stable (good for precision), creates fine dust (respiratory PPE needed). Use: sharp carbide tooling (diamond preferred for SP-22 graphite grade), slower cutting speeds (80-120 m/min vs 200 for PEEK), air blast or minimal coolant, HEPA dust collection. We machine Vespel with appropriate procedures — just plan slightly longer lead times vs easier plastics.

Q: Availability and lead times?

Common Vespel grades (SP-1, SP-21, SP-22): in stock or 1-week material lead time. Specialty grades (SP-3, SP-211, CR-6100): 2-4 week material lead time from DuPont. Custom colors: not standard (natural golden-brown only). For urgent Vespel orders, confirm material availability before PO. Standard manufacturing lead time: 7-14 days after material in hand.

Q: Why self-lubricating?

Graphite-filled Vespel (SP-21, SP-22) contains graphite particles that transfer to mating metal surfaces, creating a solid-lubricant film. This film provides very low friction (coefficient 0.1-0.15 vs 0.5 for most plastics against steel) without any added liquid lubricant. Standard for aerospace and satellite bearings where lubrication cannot be maintained — no grease, no oil, decades of reliable operation.

Vespel (DuPont polyimide) handles 300 °C continuous service — 40 °C hotter than PEEK. Exceptional dimensional stability, low outgassing for vacuum, natural self-lubrication. Used for aerospace bearings, semiconductor handling, vacuum hardware. Premium material for applications beyond PEEK.

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Technical plate for Highest-temperature plastic. Low outgassing. Aerospace beari

At a glance

Density: 1.43 g/cc
Tensile strength: 86 MPa
Flexural modulus: 3.1 GPa
Elongation: 7.5 %
HDT (1.8 MPa): 360 °C
Tg: N/A (amorphous)
Continuous service: 300 °C
Outgassing (TML): < 1%

Vespel · Polyimide

Key data

Density: 1.43 g/cc
Tensile strength: 86 MPa
Flexural modulus: 3.1 GPa
Elongation: 7.5 %
HDT (1.8 MPa): 360 °C
Tg: N/A (amorphous)
Continuous service: 300 °C
Outgassing (TML): < 1%

01 · Grades & variants

Vespel grades.

Vespel SP-1

Pure polyimide. Best electrical properties, highest purity. Used for insulators, semiconductor handling, high-purity vacuum.

Vespel SP-21

Graphite-filled for self-lubricating bearings. Most common mechanical grade. Used for aerospace bushings, dry-running bearings, high-PV applications.

Vespel SP-22

Higher graphite content for maximum wear resistance. Used for heavy-duty bearings, seals running against metal, sacrificial wear components.

Vespel SP-211

PTFE-filled for lowest coefficient of friction. Used for pure dry-running bearings where self-lubrication is critical.

Vespel SP-3

MoS2-filled for vacuum service. Used for satellite bearings, space-grade sliding components, UHV applications.

Vespel CR-6100

Specialty grade for jet engine compressor blade shrouds, gas turbine erosion-resistant applications.

DuPont Vespel comes in several specialty grades optimized for specific applications — unfilled for general, graphite-filled for bearings, PTFE-filled for dry friction, specialty grades for semiconductor and aerospace.

02 · Why this material

When Vespel beats PEEK.

300 °C continuous

40 °C beyond PEEK's 260 °C service limit. For gas turbine hot section, continuous operation at high temperature.

Vacuum compatibility

< 1% total mass loss in vacuum. Standard for satellite bearings, semiconductor handling, UHV chamber components.

Self-lubricating

Graphite-filled grades run dry against metal with near-zero wear. No lubrication required, no maintenance.

Dimensional stability

Virtually no creep under load at elevated temperature. Precision bearings and fits maintain tolerance at temperature.

Vespel costs 3–5× PEEK — specify it only when application genuinely exceeds PEEK's capabilities or where specific Vespel properties are needed.

03 · Applications

Vespel applications.

Jet engine bearings

SP-22 engine bearings running in hot section — dry operation

Semiconductor wafer handling

SP-1 wafer carriers, end-effectors — low outgassing, high purity

Satellite bearings

SP-3 satellite mechanism bearings — vacuum-qualified, space-grade

Aerospace thrust washers

SP-21 thrust washers in aircraft actuators, flight controls

Valve seats

High-temperature valve seat hardware — chemical resistance at temperature

Oil and gas downhole

Downhole tool bearings — high-temperature, dry-running

High-temperature connectors

Electrical connector insulators in elevated-temperature service

Bushings in aircraft

Aircraft control surface bushings — no lubrication maintenance

Vacuum chamber internals

UHV chamber mechanism components — low outgassing critical

04 · Finishing

Vespel finishing.

As-machined

Golden-brown color. Single-pass finish Ra 1.6 µm. Machines with care using carbide tooling.

Polished

Ra 0.4 µm achievable with fine finish passes. Specialty application.

Laser marked

Excellent contrast on Vespel surface. Standard for part identification.

Cleaned

Ultrasonic cleaning in IPA or alcohol for semiconductor and UHV applications.

Post-machined

Secondary machining operations can be performed — Vespel is dimensionally stable.

Bonded

Vespel can be bonded with specialty adhesives — surface preparation required.

Cannot weld

Vespel is not thermoformable or weldable — it's a thermoset-like polymer.

No plating

Vespel cannot be electroplated — chemically too stable.

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FAQ

Highest-temperature plastic — questions

Why is Vespel so expensive?

Vespel raw material: $500–800/kg (yes, eight hundred per kilogram). PEEK unfilled: $120–180/kg. Nylon: $8/kg. Vespel premium reflects: (1) Extreme difficulty of polyimide synthesis, (2) Specialty forming process (compression molded from powder, not injection molded), (3) Small production volumes globally. Use Vespel only when application genuinely requires its unique capabilities — the cost is usually justified by elimination of lubrication systems or enabling continuous high-temperature operation.

Vespel vs PEEK — when is each right?