GLOSSARY
Carbon Fiber Filament
Carbon fiber filament is a base plastic — usually nylon, PETG, PLA, or PA-CF — blended with short, chopped carbon fibers. The fibers add stiffness and dimensional stability but wear hardened nozzles fast.
Definition
Carbon fiber filament contains roughly 10–20% chopped carbon fibers (a few millimeters long) suspended in a polymer matrix. When extruded, the fibers align with the print direction and stiffen the part along the layer plane. The matrix provides the fiber-to-fiber bond.
Common grades include PA-CF (carbon-fiber nylon), PETG-CF, and PLA-CF. Industrial blends like PEEK-CF exist for aerospace and medical use, requiring a printer with a 350°C+ hot end and heated chamber.
Why it matters
For functional parts that need stiffness without weight — drone frames, jigs, fixtures, robot arms — carbon fiber filament can replace machined aluminum at a fraction of the cost. Parts also have a matte black finish that many people prefer cosmetically.
You need a hardened steel or ruby-tipped nozzle. Brass nozzles erode in dozens of hours of CF printing. The fibers are abrasive, and a worn nozzle ruins print quality.
Common confusion
"Carbon fiber" in filament marketing does not mean continuous-fiber composite. The fibers are short and randomly oriented; strength gains over plain nylon are real but moderate (typically 1.5–3x stiffness, similar tensile strength). Continuous-fiber printing — Markforged, Anisoprint — is a different process entirely.
CF filament is also more brittle than its base plastic. Parts that flex without breaking in PETG can snap in PETG-CF.