Grades / PEEK GF30
PEEK GF30, stiffness and creep resistance while hot
GF30 is the grade for a part that carries load while it is hot and still has to insulate. Thirty percent short glass fibre roughly triples the stiffness of unfilled PEEK and pushes heat deflection above 300 °C. It gives up toughness and it is hard on tooling and on whatever it slides against.
PEEK GF30 against the other grades
Typical published values. The full matrix, with what each row changes, is on the property data page.
| Property | Unit | PEEK GF30 | Unfilled | GF30 | CF30 | Bearing |
|---|---|---|---|---|---|---|
| Density | g/cm³ | 1.49 - 1.51 | 1.30 - 1.32 | 1.49 - 1.51 | 1.40 - 1.44 | 1.44 - 1.46 |
| Tensile strength | MPa | 150 - 170 | 90 - 100 | 150 - 170 | 130 - 140 | 90 - 110 |
| Tensile modulus | GPa | 9 - 11 | 3.5 - 4.0 | 9 - 11 | 12 - 14 | 7 - 9 |
| Coefficient of friction, dry against steel | µ | 0.35 - 0.45 | 0.30 - 0.40 | 0.35 - 0.45 | 0.20 - 0.30 | 0.10 - 0.20 |
| Thermal expansion, below Tg | µm/m·K | 20 - 24 | 45 - 50 | 20 - 24 | 14 - 18 | 18 - 24 |
| Thermal conductivity | W/m·K | 0.40 - 0.45 | 0.25 | 0.40 - 0.45 | 0.85 - 0.95 | 0.6 - 0.9 |
| Volume resistivity | Ω·cm | > 10¹⁵ | > 10¹⁵ | > 10¹⁵ | 10³ - 10⁶ | 10³ - 10⁶ |
| Tolerance a shop quotes | mm | ±0.05 | ±0.05 | ±0.05 | ±0.025 | ±0.05 |
Choose it when
- Load held at temperatureCreep resistance is the reason this grade exists. Brackets, housings and clamp blocks that stay loaded while hot.
- Stiffness with insulationAbout 9 to 11 GPa and still above 10¹⁵ Ω·cm, which carbon filled cannot offer.
- Dimensional stability on a budgetExpansion around 22 µm/m·K, half of unfilled, at a lower stock price than CF30.
- Pressure partsValve bodies and pump housings where the wall has to hold shape under load.
Look elsewhere when
- Anything that slidesGlass fibre is abrasive and will score the shaft or rail it runs against. This is the most common misuse.
- Repeated autoclave cyclesFibre ends at a machined surface give steam a path in, and the grade is more brittle than unfilled.
- Impact or snap fitsElongation of 2 to 3%. It cracks where unfilled bends.
- Mirror finishesFibre shows at the surface, so a sealing face usually wants unfilled stock.
What changes in the shop
What a shop prices differently for this grade, and what that means for your drawing.
Fit calculator and annealing calculator both use these numbers.
- Tool wear is the cost lineRoughly three times unfilled. Shops price fresh tooling in, and diamond coated or PCD pays back on volume.
- Separate toolingCareful shops keep filled and unfilled tools apart so glass dust never reaches medical work.
- AnisotropyShort fibre stock is stronger along the extrusion direction. Say which way the load runs on a long part.
- Tolerance±0.05 mm typical. Filled grades hold outside diameters better than unfilled because they move less with temperature.
Typical parts
Where this grade turns up in practice.
- Structural brackets and clamp blocks
- Pump and valve bodies
- Insulating hardware under load
- Hot process equipment fittings
- Bushings where the mating part is soft and replaceable
- Housings that must not creep
Questions about PEEK GF30
More in the full question list.
Is GF30 stronger than CF30?
In tensile strength usually yes, 150 to 170 MPa against 130 to 140. In stiffness no, and in dimensional stability no. Pick on which of the three the part actually needs.
Can GF30 be used as a bearing?
It should not be. The glass fibre is abrasive to the mating surface, so the bushing survives and the shaft does not. Bearing grade PEEK exists for this.
Does glass filled PEEK still insulate?
Yes. Glass is not conductive, so GF30 keeps the electrical properties of unfilled PEEK. That is the main reason to pick it over CF30 on an insulator that also carries load.