PEEK is a high-performance engineering plastic that stays strong and stiff up to about 250 °C, resists almost all chemicals and steam, and wears well. It is expensive, so it is used where metals corrode or are too heavy and ordinary plastics fail: seals, bushes, valve seats, pump parts, semiconductor, medical and aerospace parts.
Quick facts
- Type
- Semi-crystalline thermoplastic
- Continuous service temperature
- About 250 °C
- Tensile strength
- About 95–100 MPa (unfilled)
- Density
- About 1.3 g/cm³
- Chemical resistance
- Excellent, including steam and most solvents
- Common grades
- Unfilled, 30% glass filled, 30% carbon filled, bearing grade
Typical properties
| Property | Unfilled PEEK | 30% carbon filled |
|---|---|---|
| Tensile strength | About 95–100 MPa | About 200+ MPa |
| Stiffness | About 3.6–4 GPa | About 15–20 GPa |
| Wear | Good | Very good |
| Colour | Beige | Black |
Values are typical for unfilled grades. Grades from different makers differ; ask for the supplier's data sheet when it matters.
Machining tips
- Stock is often annealed to remove stress before close-tolerance work
- Sharp carbide tools, low feed, and air or water-based coolant
- Allow for thermal expansion when measuring warm parts
- Carbon and glass filled grades wear tools faster
- Keep chips clean; PEEK scrap has resale value
Typical uses
- Seals, back-up rings and valve seats
- Bushes and thrust washers running dry or in water
- Pump wear rings and impellers
- Semiconductor and electrical insulating parts
- Medical and food-contact parts (approved grades)
Need parts made in PEEK plastic?
Post your requirement free. Workshops that take your kind of work see it and get in touch. You only talk to the ones that fit.
Get startedRelated
Related job work
Questions
- What temperature can PEEK handle?
- About 250 °C continuously and higher for short periods, far above nylon or acetal.
- Why is PEEK so expensive?
- The raw material is costly to make and processing needs high temperatures. It is used where its heat, chemical and wear resistance save cost elsewhere.
- PEEK or PTFE?
- PTFE has lower friction and better chemical resistance but is soft and creeps. PEEK is much stronger and stiffer, so it holds shape under load.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 22 October 2026.