PEEK is the high-performance polymer for bearings that run hot, wet and chemically aggressive at the same time: 250 °C continuous, virtually inert, and self-lubricating enough to run dry.
| Designations | PEEK · polyether ether ketone · bearing grades: PEEK-CF30, PEEK-GF30, PEEK+PTFE |
|---|---|
| Density | 1.30 g/cm³ (1.40–1.45 with fibre fill) |
| Max service temperature | 250 °C continuous · 300 °C with fibre fill, short excursions higher |
| Moisture absorption | ≈0.15–0.5% — negligible dimensional effect |
| Chemical resistance | Excellent; attacked by concentrated H2SO4 and some halogens |
| Friction | 0.15–0.35 dry, lower with PTFE/graphite compounding |
| Load capacity | 5–15% of a steel bearing of equal size |
| Relative cost | 5–8× steel |
PEEK's aromatic backbone gives it a glass transition around 143 °C and a melting point near 343 °C, so it keeps stiffness and creep resistance well above where POM or nylon have softened. It absorbs almost no water, which means a PEEK bearing holds its clearance in a wet plant — the failure mode that ruins nylon bearings.
Unfilled PEEK is rarely used for bearing surfaces. Carbon-fibre filled grades raise strength and stiffness; graphite and PTFE additions lower friction and raise the PV limit. The compounding, not the base polymer, decides the rating.
Rate the bearing on pressure × velocity at the operating temperature, not at 20 °C. PEEK's allowable PV falls steeply above 150 °C. Allow for thermal expansion — about 4.7×10⁻⁵/K, roughly five times steel — so clearance must be larger than a metal design at the same temperature. And provide a heat path: polymers conduct heat poorly, so frictional heat accumulates at the contact.
| Property | PEEK | POM | PA66 | PTFE |
|---|---|---|---|---|
| Max continuous temp | 250 °C | 90 °C | 100 °C | 260 °C |
| Moisture absorption | ≈0.3% | ≈0.2% | 1.5–2.5% | <0.01% |
| Friction (dry, vs steel) | 0.15–0.35 | 0.2–0.35 | 0.2–0.4 | 0.04–0.10 |
| Chemical resistance | Excellent | Good | Fair | Exceptional |
| Load capacity | Moderate | Moderate | Moderate | Very low (creep) |
| Relative cost | 5–8× | 1.5× | 1.2× | 4× |
Bushings and bearing rings immersed in aggressive fluid.
Read →Hot washdown where grease is not allowed to escape.
Read →6000/6200 series with PEEK rings or PEEK cages in steel bearings.
Read →When friction must be lower and load even lighter.
Read →Yes — that is a main reason to choose them. The PV limit when dry is lower than when lubricated, and a PTFE- or graphite-filled grade raises it substantially.
PEEK itself is widely accepted for food contact and is steam-sterilisable. The declaration you need is for the specific grade and any lubricant used, and it should come from the compounder.
PEEK where the bearing carries load or runs at speed; PTFE where friction must be minimal and the load is very light. PTFE creeps under sustained load, which is why it is rarely a structural bearing material.
Usually heat: poor heat path, too little clearance for thermal expansion, or a PV calculation done at ambient temperature. Check the running temperature before changing the material.
| Industry | Duty | Where it fits | |
|---|---|---|---|
| Pumps & Compressors | continuous running, thrust reversal and process fluid along the shaft | Chemical, dry running | Detail → |
| Automotive & Electric Vehicles | shock load, wide temperature swings and electrical erosion from the inverter | Under-hood & high temp | Detail → |
| Robotics & Automation | high cycle count, oscillating motion and zero tolerance for play | Dry-running joints | Detail → |
Model numbers, quantities and the application — we reply with brand options, price and lead time within 30 minutes on working days.