Carbon-fiber PETG: documented values and recommended nozzle

What the Spectrum datasheet actually publishes

The Spectrum PET-G Carbon technical datasheet describes a PETG-based filament blended with 10% carbon fibers. According to the document, the fibers bring considerably higher rigidity, hardness and tensile resistance than pure PETG, while keeping the low shrinkage and good build-plate adhesion typical of the base material. The datasheet states that the mechanical values were measured on 3D-printed specimens rather than molded ones. That detail matters: the numbers describe a printed part made under the manufacturer's conditions, not the raw polymer.

Every property is tied to a standard. Specific gravity follows ISO 1183, the tensile tests follow ISO 527-1 at a speed of 5 mm/min, Charpy impact follows ISO 179-1eU on an 80 x 10 x 4 mm specimen, and the VICAT softening point follows ISO 306. What the datasheet does not state is the print orientation of the specimens, their layer height or their infill. You should read these figures as indicative, which is exactly how the manufacturer frames them in its disclaimer: the data are intended for reference and comparison purposes only, and should not be used for design specifications or quality control.

Modulus, elongation and impact: read each test separately

The published modulus is 4250 MPa on a printed specimen; tensile strength at break is 45 MPa. The measured elongation at break is 4.90% for that specimen and those conditions, not a measurement of how much any particular part will deform. The sheet labels its data indicative and for comparison; it cannot predict how a real part will fail.

The unnotched and notched Charpy specimens give 17 and 5.4 kJ/m² respectively under ISO 179-1eU. That difference belongs to the stated specimens and method; the sheet does not quantify how a particular geometry affects a printed part. The Vicat softening point is 80 °C under 50 N at a heating rate of 50 °C/h.

Hardened or ruby nozzle: recommendation and setup checks

The PET-G Carbon sheet lists a ruby or hardened nozzle as recommended, with published settings based on a 0.4 mm nozzle. It does not explain why or call the recommendation mandatory. The Filament PETG CF 3% page also lists a ruby or hardened nozzle as recommended for that separate reference; this neither turns the recommendation into a requirement nor proves both products share every constraint.

Before buying a spool, check three points on your printer: the material of the installed nozzle, whether a compatible nozzle is available if you choose to follow Spectrum’s recommendation, and the diameter used in the profile. The nozzle guide covers general selection criteria. The PET-G Carbon TDS recommends ruby or hardened steel but does not name tungsten carbide; check any replacement nozzle with its maker. The datasheet’s improved abrasion-resistance feature describes the printed part, not nozzle wear.

Published print settings: temperatures, cooling, speed, enclosure and storage

For PET-G Carbon, the datasheet lists a nozzle temperature of 230 to 255 °C and a bed temperature of 60 to 80 °C. The part cooling fan is on, up to 100%. Recommended print speed runs from 30 to 70 mm/s, layer height from 0.05 to 0.30 mm and shell thickness from 0.40 to 2.70 mm, with those three ranges flagged as dependent on geometric complexity. The manufacturer states that a closed chamber is not necessary and that a dry box is not necessary either.

This is limited to the datasheet statement: a closed chamber and dry box are not necessary for this grade. The same sheet recommends dry storage at room temperature, ideally 18 to 25 °C, away from moisture, sunlight and direct heat. It states a 24-month shelf life under those conditions. Do not turn the absence of a dry-box recommendation into a conclusion about every active-drying method.

PET-G Carbon 10% versus The Filament PETG CF 3%: two different products

Spectrum also lists The Filament PETG CF with 3% fiber, separate from PET-G Carbon 10%. Its page publishes settings for that reference and says a ruby or hardened nozzle is recommended, not mandatory. It mentions AMS compatibility and promotional use cases, but the text reviewed provides no numeric mechanical value for this grade. Do not transfer the 4250 MPa modulus from the 10% product to the 3% reference.

For The Filament PETG CF 3%, the page lists 240–265 °C nozzle, 60–80 °C bed, 40–200 mm/s and 75–100% cooling. It also says an enclosure and dry box are unnecessary. These are the announced settings for that reference, without a result promised on every profile or printer. The AMS statement does not detail every generation and setup; check correspondence with your installation before selecting the product. The carbon-fiber filament guide places other formulations in context.

Check the datasheet version before sizing a part

The PET-G Carbon datasheet carries a preparation date of April 2022. Before you copy a figure into a specification, download the current version from the manufacturer and compare the dates: a reformulation or a new round of testing can change the values. The manufacturer writes that actual values vary with printing conditions, model complexity and environmental conditions.

To attempt test reproduction, information still missing includes printed orientation, infill and specimen wall count. The sheet also supplies no test temperature here. Keep the values indicative, matching the manufacturer's stated documentary status. For a loaded part, define acceptance criteria and verification appropriate to the use; observing a sample at home does not turn these data into design specifications. The startup-budget tool lets you record selected equipment without making a nozzle purchase mandatory or inventing its price. Include the actual nozzle identity and diameter in that record so a later hardware change remains visible when you compare your samples.

Sources and limits

• Spectrum — PET-G Carbon technical data sheet, 6 April 2022
• Spectrum — The Filament PETG CF 3%, product and printing guidance

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.