PLA-CF vs PETG-CF: Which Carbon Fiber Filament Actually Earns Shelf Space?

Two spools, similar price, both say carbon fiber on the label, both print matte black parts that look like they came off a machine shop floor. So which one goes in the printer? I run both here every week, and the difference shows up the first time a part sits in a hot car, a garage, or next to a drive motor.

What Each One Actually Is

PLA-CF is PLA with chopped carbon fiber blended in. It prints easy, looks good, and it is cheap. PETG-CF is the same idea applied to PETG — carbon fiber for stiffness and a matte finish, plus less warp than straight PETG.

Both are rigid and dimensionally stable enough for brackets, jigs, shop fixtures and prototypes. Neither one is a nylon replacement, and neither should be sold as one.

Heat Is Where They Split

The numbers decide most real jobs. PLA-CF glass transition sits around 55-60°C, and heat deflection is right there with it. Leave a PLA-CF part on a dashboard in July and it will creep and sag under its own weight. I have watched it happen on a phone mount I reprinted twice before giving up.

PETG-CF runs roughly 80°C glass transition with heat deflection in the mid-70s. That is not PPA-CF territory, but it holds up in a garage, on a machine guard, or anywhere a part gets warm without getting oven-hot.

Settings I Actually Run

PLA-CF: 220-230°C nozzle, 55-60°C bed, part cooling 80-100%, and 50°C for four hours in the dryer if the spool has been sitting open.

PETG-CF: 250-260°C nozzle, 75-80°C bed, part cooling 40-60%. More fan on PETG-CF means weaker layer bonds, so I keep it low and let the ramp start after layer three. Dry it at 65°C for five to six hours. Wet PETG-CF foams and pops, and it leaves a rough surface no amount of tuning will fix.

Both: 0.6mm hardened nozzle, 0.24-0.28mm layers, flow ratio calibrated per spool. PETG-CF wants a slower first layer — 20mm/s — and a slightly wider squish, because it does not like being dragged around cold.

When PLA-CF Still Wins

Indoor parts that never see more than 50°C. Display pieces, prototypes, organizers, anything cosmetic. PLA-CF prints faster, costs less per gram, and has better surface finish. If the part never gets hot, paying more for PETG-CF buys you nothing.

The Short Answer

Parts that live in a vehicle, a hot enclosure, or under load at temperature go PETG-CF. Everything else can stay PLA-CF.

For the spool I keep loaded, I have had clean runs from Elegoo PETG-CF — it dries fast, holds dimension well at 255°C, and the finish hides layer lines. Pair it with a plate that releases PETG without a fight, like the BIQU Cryogrip Pro, and you stop scraping parts off textured PEI at 80°C.

If your parts need more than PETG-CF gives you, step up to TINMORRY PA6-CF and print with an enclosure.

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