How to Print PET-CF Filament: Settings, Drying and Annealing

To print QIDI PET-CF, dry the spool at 100 °C, print with a 280–300 °C nozzle and a glued 70–80 °C bed, keep the part cooling fan low or off, and use a hardened steel or bimetal nozzle of 0.4 mm or larger. PET-CF does not need a heated chamber: QIDI's data sheet lists the chamber at room temperature, so an enclosed printer is enough. The rest of this guide explains where each number comes from and what to change when a print goes wrong.

What Is PET-CF Filament?

PET-CF is a 3D printing filament made from polyethylene terephthalate (PET) reinforced with chopped carbon fiber. PET is the semi-crystalline polyester behind drinks bottles and synthetic fibres. It is not the same polymer as PETG: the "G" in PETG is a glycol modification that stops the polymer crystallising, which makes PETG easy to print but also caps its heat resistance. PET keeps its ability to crystallise, and the short carbon fibre reinforcement adds stiffness and cuts shrinkage.

QIDI PET-CF ($39.99 per 1 kg spool) is positioned as the easy-to-print engineering composite in the range. QIDI's product page lists low moisture absorption, creep resistance, chemical resistance and heat resistance, and states that no heated chamber is required. Its benefit over PETG-CF is heat resistance and stiffness; its benefit over nylon composites is moisture: QIDI states that absorbed moisture does not affect PET-CF's mechanical properties or dimensional stability.

One thing a careful reader should know before trusting any number: QIDI publishes two sets of figures for this filament. The product page carries one table, and the current technical data sheet (TDS), titled QIDI PET-CF17, V1.0, carries another. QIDI's own filament comparison chart links "PET-CF17" to the same PET-CF product page, so the TDS is the more recent document. Where the two disagree, this guide shows both and says which one it follows.

QIDI PET-CF Properties

On the current TDS, PET-CF reaches 64.1 MPa tensile strength in the X-Y plane and a heat deflection temperature of 105.2 °C at 1.8 MPa. Test methods are listed so you can compare like with like. Across layers (Z axis), strength falls to about 40% of the in-plane value, which matters more for part design than any headline figure.

Two conditions attach to those numbers. First, heat deflection temperature depends on the load: the same material scores 155.3 °C at 0.45 MPa and 105.2 °C at 1.8 MPa, so always quote the load with the figure. The TDS does not say whether its HDT specimens were annealed, although it recommends annealing "to achieve the best performance". Second, the 79.5 °C glass transition is where the amorphous part of the polymer softens; the crystalline fraction and the fibre are what carry load above it.

What Print Settings Does PET-CF Need?

Start at a 290 °C nozzle, an 80 °C bed with glue, the part cooling fan off, and a moderate speed. The 280–300 °C band is where the TDS range (270–300 °C) and the product page range (280–320 °C) overlap, so it is safe under either document.

If you see clogging on a 0.4 mm nozzle, QIDI's engineering materials guide recommends moving to 0.6 mm and keeping speed to roughly 100 mm/s for carbon- and glass-fibre filaments. The same page suggests printing many small parts one object at a time rather than layer by layer, because long layer times let each layer over-cool before the next one lands, which weakens Z-axis bonding.

What Hardware Does PET-CF Need, and Which QIDI Printer Fits?

PET-CF needs an abrasion-resistant nozzle, a hotend that reaches 300 °C, a bed that holds 80 °C, and an enclosure. It does not need an actively heated chamber. QIDI lists brass and copper-plated nozzles of any size as not recommended, because the carbon fibre wears the bore.

• Nozzle: hardened steel or bimetal, 0.4 / 0.6 / 0.8 mm. Avoid 0.2 mm on any fibre-filled filament.
• Build plate: QIDI PEI, HF or Smooth plate, with glue stick or 3D LAC spray. QIDI lists the PC plate as not recommended.
• Enclosure: QIDI's filament comparison chart marks PET-CF as a closed-chamber material, but the TDS sets chamber temperature at room temperature.
• Supports: QIDI pairs PET-CF with S-White support material for cleaner support-facing surfaces on complex models.

That combination makes PET-CF the engineering composite that fits the cheapest machine in the lineup. The QIDI Q2C ($349) ships with a bimetal hardened steel nozzle, a 370 °C hotend, a bed rated to 120 °C and an enclosed, flame-retardant chamber. Its spec sheet lists no chamber heating, and for PET-CF that is not a limitation. If you already know you will move on to PAHT-CF or PPS-CF, the Q2 ($499, same 270 × 270 × 256 mm volume) adds a 65 °C actively heated chamber. The Plus 5 ($749, 320 × 320 × 300 mm) and Max4 ($1,049, 390 × 390 × 340 mm) are the choice when part size, not material, is the constraint. On any of the three heated machines, you can leave the chamber heater off for PET-CF.

How Do You Dry and Store PET-CF?

Dry PET-CF at 100 °C in a blast drying oven: 4–8 hours per the product page, 10 hours per the TDS. Then print it from a sealed container held below 15% RH. The low 0.53% water absorption can mislead people. QIDI's own printing tips say that PET is very sensitive to moisture even though it absorbs little, and that damp filament oozes, extrudes with bubbles and prints a rough surface.

• Use the shorter 4–8 hour cycle for a spool you have just taken out of its vacuum foil bag, and the full 10 hours for a spool that has sat open.
• If your dryer cannot reach 100 °C, QIDI's wiki drying table lists 75–85 °C for 8–12 hours for PET-CF and PAHT-CF. It is a longer cycle at a lower temperature, not a substitute you can shorten.
• After drying, move the spool straight into a sealed container with desiccant. The QIDI filament dryer box ($39) is a sealed, desiccant-based storage box that feeds while printing. It keeps a dried spool dry but does not heat it.
• Put unused filament back in the original aluminium foil bag. QIDI measured 0.014% water vapour transmission for that packaging, against 4.76% for ordinary sealed packaging.

PET-CF is on QIDI's compatible list for the QIDI Box, which dries at up to 65 °C while printing. That is a maintenance temperature, not the 100 °C initial dry. Because PET-CF ships on a cardboard spool, QIDI recommends fitting a printed spool adapter before loading it into the Box so the spool can rotate during retraction. For the general drying method across material families, see how to dry filament for 3D printing and how to store 3D printer filament properly.

Should You Anneal PET-CF Parts?

Anneal PET-CF when a part will see heat or sustained load. The TDS recommends 120 °C for 10 hours; the product page gives a gentler 80–100 °C for 4–8 hours with natural cooling. Annealing lets the PET matrix crystallise further and releases the stress frozen in during printing.

The TDS attaches precautions to the 120 °C cycle, and they are worth following exactly:

• Let the print rest for more than 24 hours first, or hold it at 80 °C for 2 hours, to relieve printing stress before the full cycle.
• Do not touch or load the part while it is in the oven, and make sure the oven temperature is even with no obstruction shading the part.
• Support bridges longer than 3 cm and any overhangs, and anneal with the supports still attached.
• Thicken walls under 4 mm or add ribs; thin walls are where annealing distortion shows first.
• Keep the part in the same orientation it was printed in; ideally put it in the oven on the build plate.

QIDI's annealing guide also warns that annealed parts shrink, so print a test piece and measure it before annealing anything with a press fit or threaded hole.

Common PET-CF Failures and Fixes

Most PET-CF problems trace back to moisture, nozzle wear, or too much cooling. Check them in that order before touching flow or retraction.

If wear is the suspect, the signs that a nozzle needs replacing covers what to look for before it ruins a part.

PET-CF vs PETG-CF, PAHT-CF and PPS-CF

PET-CF sits between PETG-CF and the high-temperature composites: it doubles PETG-CF's heat resistance at 0.45 MPa without needing a heated chamber, but PAHT-CF and PPS-CF go much further on heat. The table uses QIDI's filament comparison chart so every figure is measured the same way.

How to read it, by condition:

• If the part stays well below PETG-CF's 77.0 °C HDT and you want the easiest print, PETG-CF is cheaper and QIDI does not require an enclosure for it.
• If the part has to hold its shape above PETG-CF's range and humidity is a concern, PET-CF is the step up: 105.2 °C HDT at 1.8 MPa, 0.53% water absorption, and it runs on a Q2C. Test a real part at its real service temperature before relying on it.
• If Z-axis strength or wear resistance decides it, PAHT-CF's 51.03 MPa layer strength is roughly double PET-CF's. It costs more, prints hotter, and cannot go through the QIDI Box. The PAHT-CF printing guide covers it in detail.
• If the requirement is sustained heat above 200 °C, chemical exposure or flame retardancy, go to PPS-CF and a heated chamber; see how to print PPS-CF.

For the full family, including PA-based options such as UltraPA-CF25, read the carbon fiber filament guide. If you are weighing PET-CF against nylon composites, the nylon 3D printing guide explains why PA absorbs more water and what that does to a part.

PET-CF Frequently Asked Questions

What temperature should I print PET-CF at?

Print QIDI PET-CF between 280 and 300 °C with the bed at 70–80 °C and glue on the plate. The current TDS gives 270–300 °C and the product page gives 280–320 °C; 280–300 °C satisfies both.

Does PET-CF need a heated chamber?

No. The TDS lists chamber temperature as room temperature, and the product page says no heated chamber is required. QIDI's comparison chart does mark it as an enclosed-printer material, so print it with the door and lid closed.

Is PET-CF the same as PETG-CF?

No. PET can crystallise and PETG cannot, which is why QIDI's chart shows PET-CF at 155.3 °C HDT (0.45 MPa) against 77.0 °C for PETG-CF. PET-CF also prints about 30 °C hotter.

Can I print PET-CF on a brass nozzle?

QIDI lists brass and copper-plated nozzles as not recommended for PET-CF. The carbon fibre wears the bore, and the first symptom is usually under-extrusion that calibration will not fix.

How long should I dry PET-CF?

At 100 °C, 4–8 hours per the product page or 10 hours per the TDS. Use the longer time for spools that have been open, then keep the filament below 15% RH while printing.

What is the difference between PET-CF and PET-CF17?

QIDI's comparison chart labels the PET-CF product as "PET-CF17", and the current TDS carries that name. The TDS does not state the fibre percentage, so this guide does not assume one.