CF-PLA is PLA filament compounded with chopped carbon fibers, typically about 10–20% by weight and well under a millimeter long. The fibers raise stiffness, cut shrinkage and warping, and give printed parts a fine matte, dark finish that hides layer lines better than glossy PLA. It is not a continuous-fiber composite: the PLA matrix still sets strength, toughness and heat resistance.
Choose CF-PLA for stiff, dimensionally stable parts that stay at room temperature: jigs, fixtures, drill guides, mounting plates, camera and sensor brackets and presentation parts with a technical look. Its limits come from PLA and from the fibers: it softens above about 55 °C, is more brittle than plain PLA, and is abrasive, so it is printed with hardened or other wear-resistant nozzles. It is offered for FDM through Uretyco's partner network.
Mechanical and physical properties
| Property | Typical value | Notes |
|---|---|---|
| Tensile strength | ≈ 35–55 MPa | In the layer plane (XY); similar to or slightly below unfilled PLA. Across layers (Z) far lower. |
| Tensile modulus | ≈ 3.5–6 GPa | Up to about twice unfilled PLA in XY; strongly dependent on fiber content and grade. |
| Elongation at break | ≈ 1–4% | Lower than unfilled PLA: parts snap with little warning. |
| Impact resistance | Low | Lower than unfilled PLA; thin features and sharp corners crack first. |
| Density | ≈ 1.2–1.3 g/cm³ | Similar to unfilled PLA. |
| Heat deflection temperature | ≈ 55–65 °C | At 0.45 MPa, unannealed; only slightly above PLA because the PLA matrix still softens. |
| Max service temperature | ≈ 50–55 °C | Lower under sustained load. |
| Warping and shrinkage | Very low | The fibers restrain shrinkage, so long, flat parts stay flatter than in unfilled PLA. |
| Abrasiveness | High | Wears brass nozzles quickly; printed with hardened steel or similar wear-resistant nozzles. |
| Electrical conductivity | Not reliably conductive | Do not assume ESD or shielding performance unless the grade datasheet states it. |
Typical ranges from datasheets of chopped-carbon-fiber PLA filaments, measured on printed specimens. Values vary with fiber content, brand, nozzle size, orientation, wall count and infill, and properties across layers are the weak link. Validate load-bearing parts with real printed samples in the expected environment.
Printing CF-PLA with FDM
CF-PLA prints at PLA-like temperatures with very little warp and needs no heated chamber. The fibers bring their own requirements: they wear standard nozzles, call for larger nozzle diameters and make the material more notch-sensitive. Design and ordering points:
- Orientation: parts are weakest between layers, and the fibers align with the extrusion direction, so stiffness is highest along the printed beads. Put the main load path in the layer plane and say so in the order notes if orientation matters.
- Nozzle and detail: CF-PLA is usually printed with a hardened nozzle of 0.4 mm or larger, often 0.6 mm, to avoid clogging. Very fine details, small text and thin walls come out coarser than in unfilled PLA.
- Corners and thin features: the material is notch-sensitive. Add fillets at the roots of ribs, bosses and clips, and avoid thin cantilevers and snap-fits.
- Walls and infill: stiffness comes mostly from the perimeters. For stiff parts, specify more walls rather than dense infill.
- Overhangs and supports: surfaces more than about 45° from vertical need supports, which leave marks on the matte surface. Mark the cosmetic faces.
- Holes and threads: drill or ream fit-critical holes and use heat-set inserts for threads, with enough wall around each insert to prevent cracking.
Tolerances and surface
Without a drawing tolerance, Uretyco applies the FDM 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 before production. CF-PLA is one of the most dimensionally stable FDM materials because the fibers restrain shrinkage, which helps flat plates and long fixtures. The matte surface hides layer lines well, but larger nozzles produce slightly coarser edges and features.
Finishing options
Most CF-PLA parts are used as printed, because the matte finish already looks finished. Where more is needed, mechanical finishing and coatings work, but sanding exposes fibers and produces fine carbon dust.
| Finish | Effect | Notes for CF-PLA |
|---|---|---|
| As-printed | Matte, dark finish at the lowest cost | Layer lines are less visible than on glossy PLA; support marks remain. |
| Light wet sanding | Smoother surface | Exposes fibers and can leave a lighter, hazy tone; wet sanding keeps dust and heat down. |
| Primer and paint | Color, uniform appearance | Paints well; specify a RAL code or sample and mask fit faces. |
| Drilling and reaming | Accurate holes and fits | Fibers wear cutting tools faster than unfilled PLA; limit machining to the features that need it. |
Carbon fiber raises stiffness, but CF-PLA has similar or lower tensile strength than plain PLA and breaks more easily under impact. For parts that take shocks, flex or carry loads near 50 °C, choose PETG-CF, a carbon-filled nylon or an unfilled tough material instead.
Cost and lead-time drivers
CF-PLA costs more than plain PLA, but the print itself still drives 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 nozzle: the filament costs more than PLA and needs a printer fitted with a wear-resistant nozzle.
- Supports and orientation: support-heavy geometry adds material, print time and clean-up, and supports leave marks on the matte surface.
- Post-processing: drilling, reaming, inserts and painting are manual work and can cost more than the print.
CF-PLA vs. related FDM materials
| Material | Stiffness | Toughness | Heat resistance | Printing | Best for |
|---|---|---|---|---|---|
| CF-PLA | High (≈ 3.5–6 GPa) | Low; brittle | ≈ 50–55 °C | Easy; abrasive, hardened nozzle | Stiff jigs and fixtures at room temperature |
| PLA | Medium (≈ 2.3–3.5 GPa) | Low; brittle | ≈ 50 °C | Easiest | Visual prototypes, fit checks |
| PETG-CF | Medium to high (≈ 2.5–6 GPa) | Moderate | ≈ 65–70 °C | Easy; abrasive, needs dry filament | Functional parts with mild heat and chemicals |
| CF nylon (FDM) | High (≈ 4–8 GPa, dry) | Good | ≈ 80–120 °C | Demanding; dry filament, often an enclosed printer | Loaded, warm or impact-prone functional parts |
CF-PLA offers high stiffness at low material cost, but it is also the most heat-sensitive of these materials. PETG-CF trades a little stiffness for toughness, heat and chemical resistance; carbon-filled nylon is the step up for warm, loaded or impact-prone parts. For complex carbon-filled nylon parts without supports, CF-PA12 on MJF or SLS is the powder-bed alternative.
When not to choose CF-PLA
Anything warmer than about 50 °C: cars, sunny windows, machinery. Impact-loaded parts, snap-fits and living hinges: CF-PLA cracks. Sustained loads such as clamping or press fits: the PLA matrix creeps. Long-term outdoor use. ESD-sensitive applications, unless a grade rated for them is specified. Food-contact parts: layer crevices and fiber-filled surfaces should not be treated as food-safe.
Typical applications
- Jigs, fixtures, assembly nests and drill guides used at room temperature.
- Mounting plates, brackets and holders that must stay flat and stiff.
- Camera, sensor and instrument mounts for indoor use.
- Housings and covers with a technical matte look for presentation models.
- Stiff functional prototypes before moving to nylon or metal.
- Display, trade-show and design models where a carbon look is wanted.
Specifying CF-PLA on Uretyco
- 1Upload STL, 3MF or STEP
Check units and scale; STEP helps when accuracy matters.
- 2Select CF-PLA and describe the use
Tell the AI assistant about loads, temperature and impact; it can point to PETG-CF or carbon-filled nylon if CF-PLA 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
Is CF-PLA stronger than PLA?
It is stiffer, not stronger. Tensile strength is similar to or slightly below unfilled PLA, and elongation and impact resistance are lower. Choose CF-PLA when a part must deflect less, not when it must survive higher loads or shocks.
Does the carbon fiber improve heat resistance?
Only slightly. The fibers keep the part stiffer up to the point where the PLA matrix softens, at around 55–60 °C. For warmer environments, use PETG-CF, ASA or a carbon-filled nylon.
Is CF-PLA conductive or ESD-safe?
Not reliably. Chopped fibers in a PLA matrix do not form a dependable conductive network, so electrical properties vary from grade to grade. If static dissipation matters, specify a grade that is rated for it and verify the parts.
CF-PLA or PETG-CF?
CF-PLA is usually stiffer, easier to print and slightly more dimensionally stable. PETG-CF is tougher, handles heat up to about 65–70 °C and resists more chemicals. Choose CF-PLA for room-temperature fixtures, and PETG-CF for parts near warm machinery or in contact with water and mild chemicals.
Related resources
Related materials
Composites
PETG-CF
PETG filled with chopped carbon fiber: stiffer and more dimensionally stable than PETG, tougher and more heat-resistant than CF-PLA. For functional fixtures, brackets and housings that see mild heat, moisture or chemicals up to about 65–70 °C.
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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