PEEK (polyether ether ketone) is the highest-performance machinable thermoplastic — it withstands 260°C continuous operating temperature, resists virtually all chemicals except concentrated sulfuric acid, and matches the strength of aluminum at a fraction of the weight. For aerospace, medical implant, semiconductor, and oil & gas applications, machined PEEK delivers metal-like performance with plastic’s lightweight and corrosion-resistant advantages.
CNC Machining PEEK: What’s Different
PEEK rod and plate stock costs $80-150/kg — so every machining error is expensive. It is far stiffer and harder than nylon or acetal, requiring carbide tooling with specific geometries. Feed rates are typically 30-50% lower than for acetal machining. PEEK also generates more heat at the cut than other plastics, demanding aggressive chip evacuation — compressed air or mist coolant is essential. Flood coolant is unnecessary and can contaminate the surface for medical/semiconductor applications.
PEEK Grades
- Unfilled PEEK (natural): Tan/beige color, highest elongation (30-45%), best for machined components needing maximum toughness.
- 30% Glass-Filled PEEK: Higher stiffness and creep resistance, but abrasive — requires carbide or diamond-coated tooling.
- 30% Carbon-Filled PEEK: Best wear resistance and thermal conductivity, used for bearing and seal applications. Electrically conductive.
- PEEK with PTFE: Enhanced lubricity for bearing cages and sliding components.
Frequently Asked Questions
Why is PEEK so expensive?
The monomer synthesis is complex and energy-intensive. Global PEEK production is dominated by a handful of manufacturers (Victrex, Solvay, Evonik) with limited global capacity. Additionally, the machining yield rate is lower than acetal or nylon because PEEK’s hardness makes it less forgiving of cutting parameter mistakes.
Can PEEK replace metal in my application?
PEEK replaces aluminum in weight-critical applications where 260°C is sufficient, and replaces stainless steel where corrosion resistance is needed without requiring a coating. PEEK’s strength (~100 MPa tensile) is comparable to annealed aluminum but cannot match hardened steel’s mechanical properties.
What tolerances can you hold on PEEK parts?
±0.025mm is achievable on well-fixtured PEEK parts. However, PEEK’s coefficient of thermal expansion is 50-60 μm/m·°C — about double that of steel — so temperature-controlled measurement is essential for precision fits. We machine and measure at 20±2°C for high-precision PEEK work.
Is PEEK biocompatible?
Unfilled implant-grade PEEK (specifically Victrex PEEK-OPTIMA) is FDA-approved for long-term implantable medical devices including spinal fusion cages, dental implants, and orthopedic anchors. We machine implant-grade PEEK under controlled conditions with full material traceability.
Need precision-machined PEEK components?
We machine unfilled, glass-filled, and carbon-filled PEEK for aerospace, medical, and semiconductor applications.
