Carbon-fiber-filled polyamides

Carbon fiber filled polyamides (PA-CF) are the stiffest among polyamide compounds. Reinforcement with carbon fiber (CF) delivers an elastic modulus of 17,000–25,000 MPa at a density of 1.28–1.40 g/cm³ — this is 2–3 times higher than GF analogs at lower weight. The designer gets a material that replaces aluminum or steel in critical parts, reducing their weight by 15–40%.

CF versus GF — key differences

• Stiffness: CF30 = modulus 17–22 GPa, GF30 = 9–11 GPa (2 times higher).
• Weight: CF filling is 15–20% lighter than a GF analog at the same concentration.
• Electrical conductivity: CF makes the material electrically conductive (resistance 10²–10⁴ Ω·cm) — useful for ESD protection and antistatic applications.
• Wear resistance: the friction coefficient of CF composites is lower than GF, especially in a pairing with metal.
• Limitations: price 2–4 times higher; black color; mold wear — hard coatings are required.

Types of CF filling

Short carbon fiber (SCF, 100–500 µm) — standard molding grades CF20–CF40. A good balance of price and properties. Suitable for series injection molding.

Long carbon fiber (LCF, >3 mm) — premium series with increased impact resistance. More difficult to process, require special conditions.

Hybrid CF/GF — hybrids that combine the stiffness of CF with the economy of GF. Example: PA66 CFGF30 — 15% CF + 15% GF.

Examid® series from Material Wizard

• Examid® PA66 CF20 / CF30 / CF40 — standard line based on PA66 with different carbon fiber content. CF40 — for metal-replacement parts with maximum stiffness.
• Examid® PA610 CF30 — low water absorption (0.5–1%) combined with CF reinforcement. Stable geometry in a humid environment.
• Examid® PA6 CF30 — an economical grade for series production.
• Examid® PA6 GF20/CF10 — a GF+CF hybrid for balanced properties.
• Examid® PA66 CFGF30 — a hybrid compound with 30% total reinforcement (CF + GF).
• Examid® PPA CF33 — polyphthalamide with 33% CF, combining the thermal resistance of PPA (HDT 200 °C+) and the stiffness of CF.

Fields of application

• Robotics and mechanical engineering — brackets, tie rods, gearbox housings, frames.
• Aerospace and defense industry — load-bearing lightweight parts where weight reduction is critical.
• Automotive — under-hood brackets, suspension parts, pump housings.
• Sports equipment — bicycle frames, tennis rackets, gear.
• Electrical engineering — ESD-protected housings, antistatic parts.
• Industrial 3D printing — PA-CF filaments for printing metal-replacement parts.

Choosing CF20 vs CF30 vs CF40

General rule: the higher the CF content, the higher the stiffness and the lower the impact toughness. CF20 — the best balance of impact resistance and cost. CF30 — the standard engineering grade (stiffness + sufficient toughness). CF40 — maximum stiffness for static loads. For parts with cyclic loading choose CF20–CF30; for static brackets — CF40.

Limitations of CF-PA

Processing CF compounds requires hard coatings of the barrel and screw (TiN, CrN), since carbon fiber accelerates wear by 30–50% compared with GF. The price is 4–8 times higher than PA66. Parts are always black (without coloring). Anisotropy of properties in the fiber direction must be taken into account during design. Drying is mandatory (4–8 hours at 80–100 °C).

How to choose a CF polyamide for your product

Material Wizard will help select the optimal CF grade: type of PA matrix (6, 66, 610, 12), CF concentration (20/30/40%), fiber type (SCF/LCF), additional modifiers (PTFE for anti-friction, impact modifier). Request a free consultation — we will discuss the project and offer a TDS.