PETG-CF is PETG filament compounded with chopped carbon fibers, typically about 10–20% by weight. The fibers raise stiffness, reduce shrinkage and give a matte, dark surface, while the PETG matrix keeps its toughness, good layer bonding and resistance to water, many dilute acids and alkalis, and many oils. Like other chopped-fiber filaments, it is stiffer than its base polymer but not a structural composite.
Choose PETG-CF for functional parts that must be stiffer than PETG and tougher than CF-PLA: production jigs and fixtures, brackets, machine covers, cable guides and housings near warm equipment. Its limits are a service temperature of about 65–70 °C, lower elongation than unfilled PETG, an opaque finish and an abrasive filament that needs wear-resistant nozzles. It is offered for FDM through Uretyco's partner network.
Mechanical and physical properties
| Property | Typical value | Notes |
|---|---|---|
| Tensile strength | ≈ 40–55 MPa | In the layer plane (XY); noticeably lower across layers (Z). |
| Tensile modulus | ≈ 2.5–6 GPa | Up to about three times unfilled PETG (≈ 2.0 GPa) in XY; strongly dependent on fiber content and grade. |
| Elongation at break | ≈ 3–8% | Far below unfilled PETG; failure starts at notches and sharp corners. |
| Impact resistance | Moderate | Better than CF-PLA, lower than unfilled PETG. |
| Density | ≈ 1.25–1.35 g/cm³ | Similar to unfilled PETG. |
| Glass transition (Tg) | ≈ 75–85 °C | Set by the PETG matrix; stiffness falls as Tg approaches. |
| Heat deflection temperature | ≈ 70–85 °C | At 0.45 MPa; grade-dependent. |
| Max service temperature | ≈ 65–70 °C | Lower under sustained load. |
| Chemical resistance | Good | Like PETG, resists water, many dilute acids and alkalis and many oils; check solvents and cleaning agents against the datasheet. |
| Moisture sensitivity | Moderate | The filament absorbs moisture and must be dried; wet material strings, foams and loses strength. |
| Abrasiveness | High | Printed with hardened steel or similar wear-resistant nozzles. |
Typical ranges from datasheets of chopped-carbon-fiber PETG filaments, measured on printed specimens. Values vary with fiber content, brand, drying, orientation, wall count and infill, and properties across layers are the weak link. For load-bearing parts, use the datasheet of the grade named in your quote and validate printed samples.
Printing PETG-CF with FDM
PETG-CF prints at PETG temperatures, needs no enclosed chamber and warps little. The fibers and the PETG base each add their own rules:
- Drying: PETG-CF must be printed from dry filament. Moist material strings, leaves voids and weakens layer bonding, so drying before printing is part of the process.
- Orientation: parts are weakest across layers, and the fibers align along the printed beads. Put the main load path in the layer plane and note it in the order if orientation matters.
- Nozzle and detail: printed with a hardened nozzle of 0.4 mm or larger, often 0.6 mm. Fine details, small text and thin walls come out coarser than with unfilled PETG.
- Supports: PETG bonds strongly to its own supports, so removal can scar the surface. Keep overhangs within about 45° of vertical and mark the faces where support marks are unacceptable.
- Corners and features: add fillets at the roots of ribs and bosses. PETG-CF tolerates clips and light snap-fits better than CF-PLA, but test them before ordering a batch.
- Threads and inserts: use heat-set inserts or post-machining for threads; printed threads suit low loads only.
Tolerances and surface
Without a drawing tolerance, FDM parts on Uretyco follow the default of ±0.5 mm or ±0.5%, whichever is greater; actual results vary with material shrinkage, orientation, part size, supports and post-processing, so test fit-critical features first. The fibers reduce shrinkage, so PETG-CF holds flatness better than unfilled PETG. The surface is matte and dark with subdued layer lines; it is opaque, so it cannot replace clear PETG.
Finishing options
Like PETG, PETG-CF does not respond to acetone vapor smoothing, and most parts are used with their matte as-printed surface.
| Finish | Effect | Notes for PETG-CF |
|---|---|---|
| As-printed | Matte, dark finish at the lowest cost | Subdued layer lines; support marks remain visible on the matte surface. |
| Bead blasting | Uniform matte look | Evens out the surface and softens support marks; confirm availability in the quote. |
| Primer and paint | Color, uniform appearance | Use a primer suitable for plastics; mask fit faces and threads. |
| Drilling, reaming and inserts | Accurate holes and durable threads | Fibers wear cutting tools faster than unfilled PETG; limit machining to the features that need it. |
PETG-CF stays stiff up to about 65–70 °C. Car interiors in summer, parts next to motors or heaters, and dishwasher cycles can exceed that, and loaded parts creep earlier. For hotter environments, use carbon-filled nylon or a powder-bed nylon.
Cost and lead-time drivers
PETG-CF costs more than unfilled PETG, but print time and post-processing still decide most of the price:
- Volume and build time: part size, wall count, infill and layer height set machine time; larger nozzles can shorten print time on bulky parts.
- Material and preparation: the filament costs more than unfilled PETG, must be dried and needs a printer with a wear-resistant nozzle.
- Supports and orientation: support-heavy geometry adds material, print time and careful removal.
- Post-processing: drilling, reaming, inserts, blasting and painting are manual steps.
PETG-CF vs. common alternatives
| Material | Stiffness | Toughness | Heat resistance | Chemicals and outdoor use | Best for |
|---|---|---|---|---|---|
| PETG-CF | ≈ 2.5–6 GPa | Moderate | ≈ 65–70 °C | Good chemical resistance; moderate UV resistance | Stiff functional parts with mild heat and chemicals |
| PETG | ≈ 2.0–2.1 GPa | Good | ≈ 60–70 °C | Good chemical resistance; moderate UV resistance | Tough parts, translucent covers |
| CF-PLA | ≈ 3.5–6 GPa | Low; brittle | ≈ 50–55 °C | Poor outdoors | Stiff room-temperature fixtures |
| CF nylon (FDM) | ≈ 4–8 GPa (dry) | Good | ≈ 80–120 °C | Resists oils and fuels; absorbs moisture | Loaded, warm and wear-prone parts |
| ASA | ≈ 2.0–2.5 GPa | Good | ≈ 70–85 °C | Excellent UV and weathering resistance | Outdoor housings and covers |
PETG-CF sits between CF-PLA and carbon-filled nylon: tougher and more heat-resistant than CF-PLA, easier to print and less moisture-sensitive in service than nylon. Choose ASA when sunlight and weather dominate, and carbon-filled nylon, or CF-PA12 on MJF or SLS, when temperatures or loads rise further.
When not to choose PETG-CF
Continuous temperatures above about 65–70 °C, or loaded parts close to that range. Transparent or translucent parts: PETG-CF is opaque, so use PETG or PC. Impact-critical parts and living hinges: use unfilled PETG, PA11 or PA12. Long-term outdoor parts with cosmetic requirements: ASA weathers better. Food-contact parts: FDM layer crevices and fiber-filled surfaces should not be treated as food-safe. Pressure-tight parts without validation: FDM walls can leak along layer seams.
Typical applications
- Assembly jigs, fixtures and nests on production lines.
- Brackets, mounts and holders near warm machinery.
- Machine covers, guards and cable guides.
- Indoor housings for electronics and sensors.
- Tool holders and fixtures in workshops exposed to water and oils.
- Drone and robot structural parts with moderate loads.
Specifying PETG-CF on Uretyco
- 1Upload STL, 3MF or STEP
Check units and scale; STEP helps when accuracy matters.
- 2Select PETG-CF and describe the use
Tell the AI assistant about loads, temperature, chemicals and outdoor exposure; it can point to carbon-filled nylon or ASA if PETG-CF is marginal.
- 3State the load direction and cosmetic faces
Note the stiffest required direction, whether orientation is critical and which faces must be free of support marks.
- 4Mark holes, threads and inserts
Add a drawing or notes for holes to be drilled or reamed and for heat-set inserts.
- 5Review the quote
Check the grade, minimum feature sizes and lead time, and test a sample before ordering a batch of fit-critical parts.
FAQ
Why choose PETG-CF over plain PETG?
For stiffness and dimensional stability. PETG-CF deflects noticeably less under load, holds flatness better, and its matte surface hides layer lines. Plain PETG is tougher, stretches further before breaking, can be translucent and costs less.
PETG-CF or carbon-filled nylon?
Carbon-filled nylon handles higher temperatures, impact and wear, but its filament must be kept very dry, and parts absorb moisture in service, which changes stiffness and dimensions. PETG-CF is easier to print, more stable in humid environments and sufficient for many fixtures up to about 65–70 °C.
Are PETG-CF parts watertight?
Not automatically. PETG bonds well between layers, but FDM walls can still weep along layer seams under pressure. More perimeters and thicker walls help; test pressure-bearing or fluid-carrying parts before ordering a batch.
Can PETG-CF be used outdoors?
For moderate exposure, often yes: PETG resists water well. For years of direct sunlight with appearance requirements, ASA is the more proven choice. Validate outdoor parts for the load and temperature they actually see, since dark parts in the sun run well above air temperature.
Related resources
- PETGThe unfilled, tougher base material.
- CF-PLAStiffer, easier carbon-filled filament for room temperature.
- CF-PA12 (Carbon-Fiber Nylon)Carbon-filled nylon for MJF and SLS.
- ASAUV-stable FDM material for outdoor parts.
- 3D PrintingTechnologies, files and cost drivers.
- Material Selection GuideChoose by requirement, not by name.
Related materials
Composites
CF-PLA
PLA filled with chopped carbon fiber: stiffer, lower-warp and with a fine matte finish, but more brittle than plain PLA and still limited to about 50–55 °C. For stiff jigs, fixtures and premium-looking indoor parts.
Composites
CF-PA12
Carbon-fiber-filled PA12 for MJF and SLS: several times stiffer than unfilled nylon at almost the same weight, for jigs, fixtures, brackets and end-of-arm tooling. Stiffer but less tough, and direction-dependent.
Composites
Glass-Filled Nylon
Nylon filled with glass beads or short glass fibers: stiffer, more heat-resistant and more dimensionally stable than unfilled PA12, but heavier and less tough. For housings, brackets, fixtures and parts near heat, printed by SLS, MJF or FDM.
Plastics
PLA
Bio-based thermoplastic and the easiest FDM material to print: stiff, accurate and low-warp, but brittle and soft above about 50–55 °C. The default for visual prototypes, fit checks and indoor fixtures that never get warm.
Plastics
ASA
Weather-resistant styrenic: ABS-like toughness and processing, with an acrylate rubber that resists UV yellowing and embrittlement. The default for outdoor housings and trim, from FDM prototypes to injection-molded production.
Plastics
PEI
Amorphous, inherently flame-retardant high-performance plastic. ULTEM 9085 and 1010 are the industrial FDM grades for aircraft interior parts, composite tooling and hot fixtures; PEI rod and plate are also CNC machined.
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