Materials
Carbon-fibre nylon, Kevlar and composite 3D printing in the UK: what is available
For stiff, light 3D printed parts in the UK, we print carbon-fibre PETG, nylon and Markforged Onyx in FDM, and we can add carbon or glass fibre laminate over a printed part. Kevlar (aramid) is not in our listed materials, so ask an engineer before you specify it.
Reviewed by HenleyPrint3D engineers8 min readUpdated
Key takeaways
- Carbon-fibre PETG gives the stiffest FDM parts for their weight, but is brittle under impact and black only.
- Nylon and Markforged Onyx suit wear and moving parts; ask for the exact grade needed.
- Composite layup adds carbon or glass fibre laminate: in mould mode the printed part is the tool, in reinforced mode the laminate stays on it.
- Kevlar is not a listed material or finish. We say so at quote rather than promise it.
- Aerospace and defence users pick these for stiffness per gram on UAV and bracket parts.
Suits
Engineers who need stiffness per gram, such as UAV structures, brackets, mounts and lightweight tooling.
Worth knowing
Chopped-fibre filled plastics are stiff but not impact-tough. For aramid (Kevlar) or continuous-fibre parts, confirm with an engineer first.
Carbon fibre and nylon materials available
Our FDM service covers standard grades and a longer list quoted on request. The relevant ones are below, using the relative ratings from our materials explorer.
| Material | Strength | Best for | Watch |
|---|---|---|---|
| Carbon-fibre PETG | Medium, very stiff | Stiff, lightweight structure | Brittle under impact; black only |
| Nylon (PA12) | High | Wear and moving parts | Absorbs moisture; shrinks and warps as it cools |
| Markforged Onyx | See the grade datasheet | Wear and moving parts | Extended list, quoted on request; confirm grade and size at quote |
| SLS PA12 | High, uniform | Complex geometry with no supports | Bed 165 x 165 x 300 mm |
Carbon fibre is available at the full FDM 3D printing build volume of 1000 × 1000 × 1000 mm, with tolerance ±0.5% (minimum ±0.3 mm). PA12 in SLS 3D printing is limited to the 165 x 165 x 300 mm bed. State the load, temperature and environment so an engineer can recommend the grade.
How chopped-carbon filled plastics behave
This section is general engineering knowledge, not a HenleyPrint3D specification. Carbon-fibre filled filaments contain short fibres, typically a few millimetres or less, mixed into the plastic. They are not the same as continuous-fibre composites, where long unbroken strands run through the part.
| Effect of short carbon fibre | Typical result | Design consequence |
|---|---|---|
| Stiffness | Often around 1.5 to 3 times the modulus of the unfilled plastic, depending on grade and fibre content | Thin walls deflect less; good for brackets, mounts and frames |
| Strength | Higher in the print direction, little change between layers | Layer-to-layer strength stays the weak plane |
| Impact toughness | Usually lower than the unfilled plastic | Avoid for parts that get dropped or shock-loaded |
| Warp and shrinkage | Usually lower than the unfilled material | Helps on larger flat parts |
| Surface | Matte, fine texture, hides layer lines | Good cosmetic finish without painting |
| Electrical and RF | Carbon is conductive and can attenuate radio signals | Keep antennas clear; consider static behaviour near electronics |
Filled materials also wear printer nozzles faster, which the printer operator manages. For the designer, section geometry usually matters more than material, because bending stiffness depends on the cube of section depth.
Worked example: geometry versus material
Take a flat bracket arm 2 mm thick. Bending stiffness scales with thickness cubed, so making it 3 mm thick gives (3/2)³ = 3.4 times the stiffness for only 1.5 times the mass. A carbon-filled grade might give 1.5 to 3 times the stiffness for the same shape and about the same mass. The best result is often both: change the section first (thicker, ribbed or a U-section), then choose the filled grade if the part is still too flexible. A rib that doubles the depth of a section raises its bending stiffness about eight-fold.
Where stiffness per gram matters: aerospace, defence and UAV parts
For aerospace and defence parts, SLS nylon and carbon-fibre filled FDM are the usual choices for stiffness per gram, with carbon-fibre nylon where a part runs warmer. Typical items are brackets, ducting, enclosures and UAV airframe components; the guide to 3D printed drone and UAV parts covers orientation and design for these.
Material selection by requirement
| Requirement | First choice from the listed range | Why |
|---|---|---|
| Stiff, light bracket, fixed load, indoors | Carbon-fibre PETG | Highest stiffness per gram in the FDM list; black only |
| Wear, sliding, repeated assembly | Nylon (PA12) in FDM or SLS | Tough with low friction; allow for moisture and shrinkage |
| Complex geometry, snap fits, ducts | SLS PA12 | No supports and fairly uniform strength |
| Impact loads | ABS, or unfilled nylon | Filled materials are less tolerant of shock |
| Warm environment | Ask for a nylon or Onyx grade and check its datasheet | Heat limit differs by grade, and PETG-based materials soften sooner than nylon-based ones |
| Skin or fairing outdoors | ASA | UV-stable; carbon-filled PETG is not an outdoor skin |
| Laminate skin over a printed core | Composite layup | Adds carbon or glass fibre where load needs it |
Nylon in practice
- Nylon takes up moisture from the air, raising toughness and lowering stiffness slightly, and changing dimensions. PA12 absorbs much less than PA6 or PA66, which is one reason it is the usual 3D printing nylon.
- Store critical nylon parts dry if they must hold a tight fit, and allow clearance in the design.
- Nylon shrinks as it cools, so long, flat or thin FDM nylon parts warp more than PETG. Add ribs and rounded corners.
- Carbon-filled grades are generally black only, so confirm the colour is acceptable before ordering.
Carbon or glass fibre laminate over a printed part
Composite layup is a finishing service with two modes.
| Mode | What happens | Use when |
|---|---|---|
| Mould | The printed part is the tool and the laminate takes its shape | You need a laminate shell and the print is the mould |
| Reinforced | The laminate is laid over the printed part and stays on it | You need extra stiffness or a skin on the printed part |
Carbon gives more stiffness for its weight and costs more. Glass is cheaper and tougher, and insulates electrically. If the printed part is a mould, it must survive the resin cure, so tell us the resin system and cure temperature.
How to specify a fibre-reinforced part
- State the load direction and size, and whether it is static, cyclic or impact.
- State the temperature range and whether the part is exposed to sun, fuel or oil.
- Say if the part is cosmetic: carbon-filled grades are black and matte.
- Mark the tight dimensions on a drawing; nylon and filled materials move in humidity and temperature.
- Ask for the datasheet of the exact grade and check the property that governs your design.
Kevlar (aramid) availability
Kevlar (aramid) is not listed among our FDM materials, SLS material or finishing options. If your design calls for aramid, tell us the part and the duty. An engineer can say what is possible, what a carbon or glass alternative would change, or whether another supplier suits the job better.
Continuous Kevlar (aramid) reinforcement explained
Kevlar is a brand name of aramid fibre. In 3D printing it usually means continuous-fibre reinforcement: a strand of aramid is laid inside a nylon part, layer by layer, by a printer with a second nozzle. This is a different process from a filament that has chopped carbon mixed through it. It is not one of our listed services, so treat the table below as background for your specification.
| Fibre | Typical strengths | Typical drawbacks |
|---|---|---|
| Carbon (continuous) | Highest stiffness and strength per weight | Brittle failure, costs most, conductive |
| Aramid (Kevlar) | Tough, energy absorbing, forgiving failure, light | Lower stiffness than carbon; sensitive to UV and moisture; weaker in compression |
| Glass | Lower cost, tough, electrically insulating | Heavier, less stiff than carbon |
Carbon-fibre filled nylon suits parts that need more stiffness, lower mass and a better surface than the unfilled plastic, with no special loads or certification requirement. Continuous fibre is justified when a part must carry high load in a known direction, or absorb impact without shattering, and you can accept the cost and the fixed fibre path. If you are unsure, send the load case with an instant quote request or contact an engineer. We will say whether a filled grade, a laminate over a printed part or a different supplier suits the part.
Frequently asked questions
Do you 3D print with carbon fibre?
Yes. Carbon-fibre PETG is a standard FDM option for stiff, light parts, and Markforged Onyx and nylon are available for wear parts. Tell us the load and environment and an engineer recommends the grade.
Can you 3D print Kevlar?
Kevlar is not in our listed materials, so we do not promise it. Contact an engineer with the part and duty to discuss alternatives.
Is carbon-fibre PETG strong?
It is the stiffest FDM option for its weight, but it is brittle under impact. For impact loads, choose ABS.
What is composite layup?
It is a finishing service where carbon or glass fibre laminate is laid in or over a printed part. In mould mode the print is the tool; in reinforced mode the laminate stays on the part.
Is carbon fibre nylon stronger than normal nylon?
It is usually stiffer, often by roughly 1.5 to 3 times depending on the grade, but not always tougher; impact resistance can fall. Check the datasheet for the exact grade, and tell an engineer the load.
What is the difference between chopped and continuous carbon fibre in 3D printing?
Chopped fibre is short strands mixed into the filament, adding stiffness through the whole part. Continuous fibre is long strands laid along a path inside the part, which gives much higher strength in that direction but needs a different printer.
Is Kevlar stronger than carbon fibre?
Not in stiffness. Carbon is stiffer, while aramid is tougher and absorbs impact better but is sensitive to UV and weaker in compression. Kevlar is not in our listed materials, so ask an engineer about your case.
Is carbon fibre nylon good for drones?
It is a common choice for stiff, light structure such as arms and mounts. Keep antennas clear because carbon attenuates radio signals, and see our drone and UAV guide.
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