For most SLS parts, PA12 (Nylon 12) is the right default: ~48–50 MPa tensile, ~11% elongation, near-isotropic, and easy to handle. Choose PA-CF (carbon-fibre nylon, ~69 MPa, ~5,300 MPa modulus, HDT ~178 °C) only when you need stiffness, edge-load strength, or heat resistance that PA12 cannot reach — and accept higher cost, more brittleness, and an abrasive, dustier powder.
We run both materials on our Fuse SLS line in our Kyiv shop, so this is a workshop comparison, not a datasheet copy-paste. The two powders look similar on a shelf and print on the same machine, but they solve different problems. Below is how they actually differ on the bench, when each one wins, and how to choose without overpaying for carbon you don’t need. Figures are from Formlabs technical data sheets for Nylon 12 and Nylon 11 CF; treat them as XY-plane, fully-cured values.
What are PA12 and PA-CF?
PA12 (Nylon 12) is the benchmark SLS polymer — a versatile, tough nylon with stable dimensions, a clean matte finish, and biocompatible grades (ISO 10993) available. It is what most people mean when they say “nylon SLS part.” If you have no specific reason to deviate, PA12 is the safe choice.
PA-CF is nylon loaded with chopped carbon fibre. On the Fuse platform that material is Nylon 11 CF — a PA11 base (already tougher and more ductile than PA12) reinforced with carbon to push stiffness and heat resistance into territory that approaches light metal brackets and tooling. The carbon makes it stiff and dimensionally stable under load and heat, but also darker, rougher, and more abrasive to process.
PA12 vs PA-CF: full comparison table
| Property | PA12 (Nylon 12) | PA-CF (Nylon 11 CF) |
|---|---|---|
| Tensile strength | ~48–50 MPa | ~69 MPa |
| Tensile modulus (stiffness) | ~1,850 MPa | ~5,300 MPa (≈3× stiffer) |
| Elongation at break | ~11% | ~4% (more brittle) |
| Heat deflection (HDT @ 0.45 MPa) | ~171 °C | ~178 °C, and far stiffer when hot |
| Density / weight | ~1.01 g/cm³ | ~1.02 g/cm³ (similar — carbon adds stiffness, not lightness) |
| Isotropy | Near-isotropic | Slight fibre-orientation effects; still good for SLS |
| Surface & colour | Light grey/white, smooth matte | Dark grey/black, coarser, fibre texture |
| Handling | Easy, low-abrasion powder | Abrasive, dustier — needs care & PPE |
| Biocompatibility | Grades available (ISO 10993, skin contact) | Not a skin-contact / medical material |
| Relative part cost | Baseline (lowest SLS cost) | Higher — premium powder, more wear, slower handling |
| Best for | Functional parts, enclosures, batches, duct/flow, living-hinge-adjacent designs | Stiff brackets, jigs & fixtures, under-hood / near-heat parts, metal-replacement tooling |
Which is stronger?
PA-CF wins on the numbers that matter for load-bearing structure. Its tensile strength is roughly 69 MPa versus about 48–50 MPa for PA12 — call it 35–40% stronger in pure tension. But “stronger” is the wrong question for most parts; stiffness is what people actually feel. There PA-CF is dramatically ahead: a tensile modulus near 5,300 MPa against PA12’s ~1,850 MPa, so a PA-CF part is roughly three times stiffer for the same wall. A PA12 bracket that flexes under hand load becomes rigid in PA-CF without redesign.
The trade-off is ductility. PA12 stretches ~11% before it breaks; PA-CF is closer to ~4%. So a thin PA-CF part that gets dropped or overloaded tends to crack rather than bend and recover. If your part must absorb impact, snap, or flex repeatedly, PA12 (or a tougher PA11/TPU grade) is the safer call — carbon stiffness is bought with brittleness.
Which handles heat better?
Both nylons are respectable in heat, but PA-CF holds its shape under load far better. Their unloaded HDT figures are close (~171 °C for PA12, ~178 °C for PA-CF), yet the real difference shows up as the part warms while bearing weight: the carbon network keeps PA-CF stiff and dimensionally stable where unfilled PA12 starts to soften and creep. For a fixture that sits near a heat source, a clamp that holds tolerance at temperature, or an under-hood bracket, PA-CF is the honest choice. For room-temperature duty, the gap rarely justifies the premium.
Is PA-CF lighter than PA12?
This is the most common misconception we correct. Carbon-fibre nylon is not meaningfully lighter — both sit near 1.01–1.02 g/cm³. Carbon fibre here buys stiffness and heat resistance, not weight savings. The weight win comes indirectly: because PA-CF is so much stiffer, you can often thin walls or delete ribs and reach the same rigidity with less material. If outright low mass is your goal, lattice/infill design in PA12 frequently beats solid PA-CF.
How do surface, finish and handling compare?
PA12 comes off the build light grey, with a clean matte surface that dyes black evenly and looks good as a finished consumer-facing part. PA-CF is naturally dark grey to black with a visibly coarser, fibre-flecked texture — many people like that “technical” look, but it is rougher to the touch and shows the carbon.
Handling is where PA-CF asks more of the shop. The carbon makes the powder abrasive and dustier: it wears recoater blades and sieves faster, demands proper extraction and PPE, and is simply messier to depowder than friendly PA12. None of this changes your finished part, but it is real cost and care on our side — and part of why PA-CF carries a price premium beyond the powder itself. Both materials post-process the same way (media blasting, dyeing, vapour smoothing where appropriate); PA-CF just takes a firmer hand.
What does each cost?
PA12 is the cost baseline for SLS — the cheapest way to get a strong, functional nylon part, which is exactly why it dominates production runs and batches. PA-CF is a premium powder, and on top of the raw material you pay for faster consumable wear and slower, more careful handling. As a rule of thumb, expect PA-CF parts to land meaningfully above PA12 for the same geometry. That premium is well spent when you genuinely need the stiffness or heat resistance — and wasted when you don’t. We quote both per-part on real geometry rather than by weight alone, because nesting and part complexity move the number more than the powder price does.
When does PA12 win? When does PA-CF win?
- Pick PA12 when: you want a strong, functional part at the best price; enclosures, housings, ducting and flow parts; small-to-mid production batches; anything needing some flex, impact tolerance, or a clean dyed finish; skin-contact or biocompatible-grade requirements.
- Pick PA-CF when: the part must be stiff and resist deflection under load; jigs, fixtures and tooling that replace machined aluminium; brackets near heat or under the hood; parts where holding tolerance at temperature matters more than impact toughness.
One more reason both materials matter: SLS needs no support structures — the loose powder cake supports the part — so either nylon prints complex geometry, internal channels, lattices, and captive assemblies in a single build. That advantage is identical whether you choose PA12 or PA-CF; the material decision is purely about mechanical and thermal behaviour, not printability. If you’re still deciding whether SLS is the right process at all, our SLS 3D printing overview covers where it beats FDM and resin.
Bottom line: how to choose
Default to PA12. It is the right answer for the large majority of functional SLS parts, and it’s cheaper, tougher against impact, and cleaner to finish. Reach for PA-CF deliberately, for a specific engineering reason: you need roughly three times the stiffness, real strength at the edges of a load, or shape stability under heat — and you can live with a more brittle, darker, pricier part. If you’re unsure, send us the part. We print both in Kyiv, we’ll tell you honestly which one your geometry actually needs, and we won’t push carbon where plain nylon does the job. Dig deeper on each material on our PA12 SLS page and PA-CF (carbon-fibre nylon) page.
Need PA12 or PA-CF parts printed in Ukraine? We’ve run SLS in our Kyiv shop since 2015 (12,000+ orders) — send your model and we’ll quote both and recommend the honest fit.