Carbon Fiber Filament Guide: PET-CF vs PPA-CF vs PETG-CF

Carbon fiber filament has a simple promise: stiffer, more stable parts than the plain base plastic. But "carbon fiber filament" covers very different materials. A PETG-CF that prints fast on a stock printer and a PPA-CF built for oil, heat and chemical exposure have almost nothing in common except the fiber.

This guide helps you pick the right one, set your printer up for it, and avoid the usual mistakes (worn nozzles, snapped filament, wet spools). It's based on our own Fibreheart carbon fiber range, so the settings and limits below come from our product pages and data sheets.

What carbon fiber actually does in filament

Short chopped carbon fibers are blended into a base polymer. The fibers form a skeleton inside the plastic, which gives you:

• Higher stiffness. The part flexes less under load.
• Better dimensional stability. Less warping and shrinkage than the unfilled plastic.
• A matte, low-gloss finish that hides layer lines.

What it does not do is make plastic tough in every sense. Carbon fiber makes filament stiffer and more brittle, which is why a spool can snap in a tight feed path. The base polymer still decides most of the heat resistance, chemical resistance and moisture behavior, so choose the base first and the fiber second.

Fiber form matters too. Powdered carbon fiber is easier to print and gives a smoother surface, while chopped short fibers give more strength and stiffness but are harder on nozzles. For a deeper look at fiber types and handling, see Demystifying Fiber-Reinforced Filaments .

Carbon fiber filament compared

Two details from the table are worth underlining. PPA-CF Core keeps the fibers in the center of the filament and leaves a pure PPA shell around them, which is how it improves layer bonding and reduces wear on your nozzle. And PETG-CF Pro uses chopped fibers rather than powder, which is why it is stiffer than a typical PETG-CF.

If you want the full PET versus PETG breakdown, read PET-CF vs PETG-CF: Differences in Performance and Applications .

Which carbon fiber filament should you pick?

You want fast, easy, stiff parts

Start with PETG-CF Pro HF. It is the easiest of the group to print, runs at high flow, and the 76°C HDT is fine for indoor and moderate-temperature use. It is a good fit for jigs, fixtures, drone frames and brackets.

You need parts that stay accurate and hold up to more heat

Choose PET-CF. Carbon fiber in a PET matrix gives low warping and good dimensional stability, and PET handles heat better than PETG. It asks a little more of your setup, including drying and a controlled environment, so it suits you once you have PETG-CF printing well.

You need heat, chemical, oil or wear resistance

Choose PPA-CF. PPA is a high-temperature nylon that absorbs far less moisture than standard PA6, and the carbon fiber adds stiffness. You need a printer that can reach 280 to 320°C.

You need the strongest layer bonding and the least nozzle wear

Choose PPA-CF Core. The core-shell design gives the highest impact strength in our range (13.1 kJ/m² Charpy, ISO 179) and is the one to pick for long runs.

If you are not sure, compare against our heat-focused picks in Best Filament for Heat Resistance .

What your printer needs

Carbon fiber is abrasive. A few hardware rules apply to all of these filaments:

• Hardened steel nozzle or better, 0.4 mm or larger. Brass wears out quickly. Rubidium or tungsten carbide nozzles last longer. For PET-CF at high speed, a 0.6 mm nozzle helps avoid clogging.
• Direct drive or a short, gentle filament path. Carbon fiber filament is brittle and can break in long, tightly curved tubes. We don't recommend PET-CF or PPA-CF Core in an AMS. PETG-CF Pro is stiff enough that it loads smoothly in systems like the AMS, according to its product page.
• All-metal hotend for PPA. PPA prints at 280 to 320°C.
• An enclosure for PPA and for large PETG-CF parts. A stable chamber temperature reduces warping and helps layer adhesion.
• A bed that reaches 80°C for PPA-CF Core, with a PEI surface and glue stick or PVP coating.

One more PPA-CF Core note: avoid CHT-style multi-path nozzles. They redistribute the carbon fiber core and can leave a noticeably rougher surface. A standard hardened steel nozzle gives the best result.

Print settings: where to start

Starting settings for PPA-CF Core, from its product page:

For PET-CF, PETG-CF Pro and PPA-CF, grab the matching slicer profile from our print setting download page and check the TDS on each product page. Tune from there.

Every printer and hotend reads temperature a little differently, so treat any starting number as a first test, not a final answer.

Drying and storage

Carbon fiber filament is only as dry as the polymer underneath it.

• PET-CF: dry at 90°C for 4 to 6 hours before printing, and keep it sealed with desiccant between uses.
• PPA-CF: store in a dry box below 15% relative humidity. If it has picked up moisture, dry it at 100°C for 4 to 6 hours.
• PPA-CF Core: ships dried and vacuum-sealed in aluminum bags and can be printed straight out of the bag unless it visibly absorbed water. If needed, dry it at 80 to 100°C for 4 to 6 hours.

Wet filament shows up as popping, stringing, rough surfaces and weak layers. Reseal the bag promptly after every use.

Common problems and fixes

• Nozzle wearing out fast. You are probably using brass. Switch to hardened steel, and consider PPA-CF Core for long runs because the shell protects your nozzle.
• Filament snapping before it reaches the extruder. Carbon fiber is brittle. Use direct drive, shorten the path, and avoid AMS-style feeders for the stiffest grades.
• Rough or fuzzy surface. Check for moisture first, then your nozzle type, especially CHT nozzles with PPA-CF Core.
• Weak layer bonding. Dry the spool, print hotter within the recommended range, and consider PPA-CF Core for better Z-axis strength.
• Warping. Use an enclosure, keep fans off for PPA, and use a PEI plate with glue.

For more diagnosis, see our filament troubleshooting guide .

Handling carbon fiber filament safely

The fibers are locked inside the plastic, so brief contact with a spool is not a concern. The thing to manage is fine particles from printing and especially from sanding or cutting.

Ventilate your space, print in an enclosure where you can, wear PU gloves when handling, and use a respirator when sanding. Core-shell filaments like PPA-CF Core also reduce fiber exposure on the surface of the filament.

Our safety section in Demystifying Fiber-Reinforced Filaments covers this in more detail.

Annealing for extra heat resistance

Annealing relaxes internal stress and lets nylon-based parts reach their full strength and heat resistance.

For PPA-CF Core, our guideline is 80 to 100°C for 4 to 8 hours, then natural cooling to room temperature.

Read the full guides: annealing PET-CF and annealing PPA-CF (PAHT-CF) .

If you are choosing between nylon bases, this comparison of PPA, PA6, PA12 and PA612 helps.

FAQ

Ready to print?

Browse the full Fibreheart carbon fiber filament range, or start with PETG-CF Pro if this is your first carbon fiber spool.

Questions about which grade fits your printer? Our support team can help at support@siraya.tech .