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Key Takeaways
All PEEK rods operate continuously at 260°C, but HDT varies by grade.
CF30 and GF30 raise HDT to 315°C under load.
CF30 reduces radial expansion by 5× vs. unfilled PEEK.
CF30 triples thermal conductivity (0.95 W/m·K) for heat dissipation.
Always use radial CLTE for bushing and seal design.
PEEK rods deliver continuous service at 260°C and share the same chemical resistance across all grades, but their thermal behavior under load varies significantly. When selecting a grade for high‑temperature applications, engineers must evaluate Heat Deflection Temperature (HDT), Coefficient of Linear Thermal Expansion (CLTE), and thermal conductivity—not just the maximum operating temperature.
Four PEEK rod grades are commonly specified for thermal performance: Unfilled (Virgin), 30% Glass Fiber (GF30), 30% Carbon Fiber (CF30), and Bearing Grade. Each grade modifies how the material conducts heat, expands under temperature, and retains rigidity under mechanical load.
This guide focuses on the thermal performance of extruded PEEK rods, providing ISO‑tested data to support precision engineering in semiconductor, aerospace, and medical applications.
Content Menu
● The Thermal performance of Different grades PEEK rods
● What is HDT of different PEEK rods?
● What is Coefficient of Linear Thermal Expansion of different PEEK rods?
● The Thermal conductivity of different PEEK rods
All grades of PEEK rods possess excellent high-temperature resistance. Their glass transition temperatures(Tg) are all at 143°C, and they can operate for a long time in an environment of 260°C. The short-term operating temperature can reach 300°C. However, apart from the working temperature, there are significant differences in their heat distortion temperature (HDT), thermal conductivity, and linear expansion coefficient, which are also worthy of our attention.
PEEK's Heat Deflection Temperature (HDT) refers to the temperature at which PEEK material, under a specified bending load, reaches the specified deflection due to heat. It is not the melting point of the material but the practical upper limit for PEEK to maintain its rigidity under the combined effect of "load + heating".
Unfilled PEEK rods HDT(ISO 75,load 1.8Mpa) is 152°C
PEEK GF30 rods HDT(ISO 75,load 1.8Mpa) is 315°C
PEEK CF30 rods HDT(ISO 75,load 1.8Mpa) is 315°C
Bearing grade PEEK rods HDT(ISO 75,load 1.8Mpa) is 315°C
As we can see,the glass fiber and carbon fiber can Significant improve the HDT of PEEK rods.
If you need higher HDT,reinforced grade PEEK rods is more suitable for you
For precision components machined from PEEK rods, the Coefficient of Linear Thermal Expansion (CLTE) serves as a critical input parameter for dimensional stability design under thermal cycling, directly governing part fit, sealing integrity, and service life in applications subject to elevated temperatures, rapid thermal transients, or strict tolerance control—such as semiconductor wafer carriers, aerospace hydraulic manifolds, and implantable surgical instrumentation.
Unlike the melt flow orientation characteristics of injection-molded parts, the molecular chains and reinforcing fibers of PEEK extruded rods align in a highly ordered manner along the extrusion axis. This structural anisotropy results in significant differences in the CLTE of the rods along the axial direction (parallel to the extrusion direction) and the radial direction (perpendicular to the extrusion direction).
We can use the data of PEEK injection sample plate as a reference, but it is necessary to clearly note the numerical differences caused by the 2 processes.
| Grade | Direction | 23–143°C (Below Tg) | 143–260°C (Above Tg) |
|---|---|---|---|
| Unfilled PEEK | Axial | 45 ppm/K | 120 ppm/K |
| Radial | 55 ppm/K | 130 ppm/K | |
| PEEK GF30 | Axial | 18 ppm/K | 18 ppm/K |
| Radial | 35 ppm/K | 35 ppm/K | |
| PEEK CF30 | Axial | 5 ppm/K | 6 ppm/K |
| Radial | 25 ppm/K | 27 ppm/K |
PEEK rods resist softening and mechanical failure under heat while simultaneously acting as effective thermal barriers.
This unique combination is precisely what makes them irreplaceable for high-temperature fixtures, semiconductor process components, and electrically insulating structural parts.
Unfilled PEEK rods Thermal conductivity is 0.29W/(m·K)
PEEK GF30 rods Thermal conductivity is 0.3W/(m·K)
PEEK CF30 rods Thermal conductivity is 0.95W/(m·K)
Note:These data is under standard ISO 22007-4,the test condition is 23°C
| Category | Specific Material | Thermal Conductivity W/(m·K) | Multiple of Virgin PEEK | Test Standard |
|---|---|---|---|---|
| Metals (High Conductivity) | Copper (Cu) | 385–401 | ~1400× | ASTM E1225 |
| Aluminum (Al 6061) | 167–205 | ~700× | ASTM E1225 | |
| Steel (Carbon) | 45–55 | ~180× | ASTM E1225 | |
| Stainless Steel 304 | 14.6–16.2 | ~55× | ASTM E1225 | |
| Titanium (Ti-6Al-4V) | 6.7–7.2 | ~25× | ASTM E1225 |
