Glass-Filled PEEK (GF PEEK) is redefining the limits of what’s possible in additive manufacturing. Here’s why this material is a game-changer across aerospace, automotive, energy, and electronics.
What Is GF PEEK?
GF PEEK, or Glass-Filled Polyether Ether Ketone, is a composite thermoplastic engineered for extreme performance. It’s essentially PEEK reinforced with 20–30% glass fibers by weight. While base PEEK already boasts impressive mechanical and thermal properties, GF PEEK pushes those metrics even further—especially when it comes to dimensional stability, stiffness, and high-heat performance—all while maintaining electrical insulation.
Technical Specifications
- Tensile Strength: 105 MPa
- Tensile Modulus: 7,250 MPa
- Flexural Strength: 130 MPa
- Flexural Modulus: 7,625 MPa
- Elongation at Break: ~1.5%
- Heat Deflection Temperature: 300°C
- Glass Transition Temperature: 140°C
- Surface Resistance: >10¹³ ohms (Electrically insulating)
- Density: 1.44 g/cm³
Compared to CF PEEK, GF PEEK trades off electrical conductivity for superior insulation and enhanced printability—making it ideal for use in electronics or sensors near high-heat sources.
When to Use GF PEEK
Use GF PEEK when your application demands high heat resistance, dimensional accuracy, and non-conductivity. It’s perfect for:
- Aerospace: Brackets and insulators exposed to thermal cycling and vibration.
- Automotive: Under-the-hood parts like sensor housings, heat shields, or throttle body insulators.
- Energy & Oil: Sensor housings and seals for drilling equipment where heat and chemicals are harsh.
- Medical: Reusable surgical guides and tools requiring sterilization and non-conductivity.
- Semiconductor: Fixtures and grippers resistant to etching fluids and requiring precision insulation.
In short: GF PEEK is your go-to when CF PEEK is too conductive and standard PEEK is too soft or heat-limited.
Printing with GF PEEK
GF PEEK isn’t plug-and-play—it demands high-end equipment and proper prep. Here are the baseline settings:
- Nozzle Temp: 450°C (Use hardened steel—glass fibers are abrasive!)
- Bed Temp: 160°C
- Chamber Temp: ≥90°C
- Dry Your Filament: Essential to prevent bubbling and poor adhesion
Use Vision Miner’s nanopolymer adhesive with a carbon fiber build plate to reduce thermal expansion mismatches and improve part release. The material prints smoother than CF PEEK, with better surface finishes and tighter tolerances, even on complex geometries.
Performance in Testing
GF PEEK held up impressively in destructive tests—torch resistance, torsion, and tensile strength. It didn’t melt under direct flame exposure, only charring without dripping. Tensile tests showed:
- XY Strength: ~3,221 units (extremely linear and strong)
- Z Strength: ~1,116–1,194 units (weaker but acceptable)
The microscope revealed solid layer adhesion in XY, though Z-axis strength varied depending on print orientation and infill quality. Regardless, its resistance to heat and deformation is unmatched in many industrial applications.
Limitations
GF PEEK isn’t perfect for everything. Avoid it when:
- High Wear Applications: Gears and moving interfaces may degrade faster due to glass fiber abrasiveness.
- Implantable Use: Unlike pure PEEK, GF PEEK is not biocompatible for implants.
Conclusion: Why GF PEEK Matters
GF PEEK is the perfect balance between strength, rigidity, thermal endurance, and electrical insulation. It surpasses standard PEEK in every way that matters for structural and high-heat parts, and it’s easier to print than CF PEEK while avoiding the conductivity issues.
Whether you’re designing parts for satellites, engine bays, medical tools, or semiconductor production—GF PEEK might just be the smartest material you’re not using yet.
Ready to test it yourself? Get your GF PEEK filament from Vision Miner today.