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Views: 0 Author: MBH Publish Time: 2026-06-25 Origin: MBH office
When designing precision components for high-performance applications, thermal expansion is often overlooked until it becomes a problem. For engineers working with PEEK (Polyether Ether Ketone), understanding its Coefficient of Thermal Expansion (CTE) is critical to ensuring dimensional stability and long-term reliability.
CTE measures how much a material expands or contracts per degree of temperature change, typically expressed in µm/m·°C (or ppm/°C). A lower CTE means the material changes less with temperature — which is essential for tight-tolerance components where even minor dimensional shifts can cause assembly failure or performance loss.
Grade | CTE (Flow Direction) | CTE (Transverse Direction) |
|---|---|---|
Unfilled PEEK | ~47 μm/m·°C | ~47 μm/m·°C |
PEEK GF30 | ~20 μm/m·°C | ~40 μm/m·°C |
PEEK CF30 | ~3 μm/m·°C | ~40 μm/m·°C |
Compared to common engineering plastics like nylon (~80 ppm/°C) or PTFE (~100 ppm/°C), unfilled PEEK already offers significantly better dimensional stability. Fiber-reinforced grades push this even further.
Adding glass fiber (GF) or carbon fiber (CF) to PEEK significantly reduces CTE, particularly in the flow direction during extrusion or molding.
Carbon fiber-filled PEEK (CF30) achieves a CTE in the flow direction close to that of aluminum (~23 µm/m·°C), making it highly suitable for metal-replacement applications where thermal compatibility between plastic and metal components is required.
Glass fiber-filled PEEK (GF30) offers a balanced improvement — lower CTE than unfilled PEEK while maintaining good impact resistance and machinability.
It is worth noting that fiber reinforcement creates anisotropy: CTE in the flow direction drops significantly, but the transverse direction remains relatively high. This is an important consideration when designing parts that experience thermal cycling in multiple directions.
In applications involving temperature fluctuations, a mismatch between the CTE of PEEK and the surrounding metal structure can cause stress, loosening of fits, or dimensional drift over time. For components with tight tolerances — such as bearing housings, guide rails, or fixture plates — even a shift of a few microns can affect function.
This is why material selection cannot rely on room-temperature properties alone. Engineers must account for the full operating temperature range and choose a PEEK grade whose CTE aligns with the assembly requirements.
- Semiconductor wafer handling fixtures and carriers
- Aerospace structural and thermal management components
- Medical implants, surgical instruments, and sterilizable parts
- High-precision bearing housings and bushing systems
- Electrical connector housings requiring dimensional stability
If you are sourcing PEEK rods or sheets for precision machining, feel free to contact us for custom sizes and grades. We offer samples for testing before bulk orders.
