PA12 and PA11 are the polyamides we print most often. Both are types of nylon sintered from powder, and after blasting they look almost the same. The differences show up when the part is bent, struck or heated, so a wrong choice usually becomes apparent only in use.
The difference in name comes from the number of carbon atoms in the repeating unit of the polymer chain, which is 12 for PA12 and 11 for PA11. PA12 is made from petrochemical feedstock and PA11 from castor oil, so PA11 is a plant-based material. That does not make a PA11 part biodegradable, but it can matter if you track the carbon footprint of your product.
Values from the Formlabs data sheets
The values below come from the Formlabs technical data sheets, for parts printed on Fuse printers and conditioned before testing. Your part may give different values depending on geometry, orientation and temperature, but the ratios between the materials remain a useful guide.
| Property | PA12 | PA11 | PA12 GF | PA11 CF |
|---|---|---|---|---|
| Tensile strength | 50 MPa | 49 MPa | 38 MPa | 69 MPa (X), 52 MPa (Y), 38 MPa (Z) |
| Tensile modulus | 1.85 GPa | 1.6 GPa | 2.8 GPa | 5.3 GPa (X), 2.8 GPa (Y) |
| Elongation at break (XY) | 11% | 40% | 4% | 9% (X), 15% (Y) |
| Notched Izod impact | 32 J/m | 71 J/m | 36 J/m | 74 J/m |
| HDT at 1.8 MPa | 87 °C | 46 °C | 113 °C | 178 °C |
| HDT at 0.45 MPa | 171 °C | 182 °C | 170 °C | 188 °C |
HDT is the heat deflection temperature, the temperature at which a standard test bar deflects by a set amount under a given stress. It is not the maximum continuous service temperature, but it is a good reference for comparing materials.
What the differences mean in practice
Stiffness and ductility
PA12 is slightly stiffer (1.85 against 1.6 GPa) and holds its shape better under load. PA11 stretches almost 4 times as far before it breaks (40% against 11%). In practice, a PA12 clip forced too hard cracks, while a PA11 clip bends and often springs back. If your part has to deform elastically in normal use, PA11 gives you more margin.
Impact resistance
In the notched Izod test, PA11 absorbs 71 J/m and PA12 32 J/m. For enclosures that may be dropped, drone parts, guards and other parts that take impacts, the difference matters. A well-designed PA12 part can also survive, but PA11 gives you a larger margin at the same wall thickness.
Behaviour at temperature
At temperature the comparison is less intuitive. Under high load (1.8 MPa), PA12 holds up to 87 °C and PA11 only to 46 °C. Under low load (0.45 MPa), PA11 reaches 182 °C, above PA12 (171 °C). If the part is hot and mechanically loaded, for example a bracket that holds something heavy near a heat source, PA12 is the safer choice, and the reinforced grades are safer still. If the part is hot but carries almost no load, both materials cope.
Accuracy, detail and warping
Formlabs publishes its minimum feature sizes for PA12 as the reference material, namely 0.6 mm walls, 1 mm holes and 0.8 mm pins. For PA11 the same minimums are slightly larger and depend on orientation. PA11 warps more easily when it has large sections in the horizontal plane, and print-in-place assemblies need at least 1 mm clearance between the parts, against 0.3–0.6 mm for PA12. For parts with fine detail and tight tolerances, PA12 is the simpler choice.
Surface and colour
Both come out matte and slightly grainy after blasting. Standard PA12 is grey and can be dyed black. If you need white or coloured parts, you can use PA12 White, which has properties close to standard PA12 (tensile strength of 47 MPa, elongation of 8%).
When to choose PA12
- Rigid enclosures, covers and brackets.
- Parts with fine detail, small text or tight tolerances.
- Large or wide parts, where warping during cooling is a risk.
- Parts under mechanical load at temperatures up to a few tens of degrees above room temperature.
- Prototypes where you do not yet know the production material, because PA12 is a neutral starting point.
When to choose PA11
- Clips and features that flex at every assembly.
- Parts that take impacts, for example on drones, robots and portable equipment.
- Parts subject to vibration, where a small crack would propagate in a stiffer material.
- Living hinges, alongside polypropylene.
- Products where the plant-based origin of the material matters.
Formlabs has tested both materials to ISO 10993 for certain biological risks in skin contact. If your product is a medical device, validation and certification remain the responsibility of the manufacturer.
Glass-filled and carbon-fibre-filled grades
If PA12 and PA11 are not stiff enough or cannot withstand the operating temperature, you can use the reinforced grades.
PA12 GF contains glass filler, which raises its stiffness to 2.8 GPa and its HDT to 113 °C. In exchange, the part is more brittle, with 4% elongation, especially between layers, and the surface is rougher than on PA12. It suits rigid brackets and parts that have to keep their shape when hot. We do not recommend it for clips.
PA11 CF contains carbon fibre and has the highest stiffness in our range, 5.3 GPa in the X direction. Its HDT at 1.8 MPa is 178 °C, and its impact resistance stays good (74 J/m). The fibres align with the X direction of the printer, so properties differ between X, Y and Z. For this reason you need to tell us the direction in which the part is loaded. It warps less than plain PA11 and handles larger sections.
Testing in both materials
If you cannot decide between PA12 and PA11, print the same part in both materials and try it under real conditions of use, for example during assembly and disassembly, in a drop test or after a day next to the heat source. For small parts, the cost of a pair of samples is small compared with the cost of a whole batch in the wrong material.
As a general rule, choose PA12 for parts that have to keep their shape and PA11 for parts that take impacts or flex often.
You can find details on each material on the PA12 and PA11 pages. For examples of parts that take impacts see drones and robotics. If you already have a model, send it for a quote and tell us what the part does, and we will recommend a material.