Materials
PA12 nylon SLS 3D printing in the UK: specification, limits and design rules
PA12 nylon SLS 3D printing produces strong, tough functional parts on a 165 x 165 x 300 mm bed, at ±0.3% (minimum ±0.3 mm), from 2 calendar days. Loose powder holds the part during the build, so nested, hollow and interlocking geometry prints without support structures. It suits clips, housings, ducting and short production runs.
Reviewed by HenleyPrint3D engineers7 min readUpdated
Key takeaways
- One SLS material: PA12 nylon. Bed 165 x 165 x 300 mm; layer height from 50 microns.
- Tolerance ±0.3% with a minimum of ±0.3 mm, the tightest percentage tolerance of our FDM, SLA and SLS figures.
- No supports are needed. Hollow parts need powder escape holes of 4 to 5 mm or more.
- Surface is matte and slightly grainy; sand blasting gives a uniform finish, and parts can be coated or painted.
- For parts over 165 x 165 x 300 mm, use FDM nylon or split the part.
- Typical published PA12 values (about 40 to 50 MPa tensile, heat deflection around 150 to 180 °C) are general; check the datasheet for the grade.
Suits
Engineers who need strong, repeatable functional nylon parts: clips, housings, ducting and short production runs.
Worth knowing
One material, one bed size. For flex, fine detail or parts above 165 x 165 x 300 mm, another process fits better.
PA12 SLS specification
| Property | Value |
|---|---|
| Material | PA12 nylon |
| Build volume | 165 x 165 x 300 mm |
| Tolerance | ±0.3% (minimum ±0.3 mm) |
| Layer height | From 50 microns |
| Minimum wall | 0.7 to 1.0 mm (typical) |
| Powder escape holes | 4 to 5 mm or more |
| Lead time | From 2 calendar days |
| Supports | None; the powder bed supports the part |
| Surface | Matte, slightly grainy |
The SLS 3D printing service page and the SLS materials page give the full specification. For how the process works, see what is SLS 3D printing?
What PA12 SLS is good for
- Snap fits, clips and living hinges.
- Ducting and housings with internal channels.
- Nested or interlocking geometry in a single build.
- Short runs of repeatable parts built straight from CAD.
- Functional prototypes and end-use parts in a tough nylon.
SLS strength is also more uniform between directions than in FDM, where parts are strongest along the layers. That makes orientation less critical for load-bearing geometry.
Typical PA12 properties (published ranges)
The figures below are typical published ranges for laser-sintered PA12 powder grades, not a HenleyPrint3D specification. Values vary by powder supplier, powder age, machine and build orientation, so check the datasheet for the exact grade when a number drives your design.
| Property | Typical range | What it means for you |
|---|---|---|
| Density (sintered part) | About 0.9 to 1.0 g/cm³ | Roughly the density of water: a 100 cm³ solid part weighs about 100 g |
| Tensile strength | About 40 to 50 MPa | Comparable to many injection-moulded nylons |
| Tensile modulus | About 1,500 to 1,800 MPa | Stiff but not rigid; thin sections flex |
| Elongation at break | About 10 to 20%, lower in the Z direction | Tough and slightly ductile, so snap fits survive repeated use |
| Heat deflection (0.45 MPa) | About 150 to 180 °C | Good short-term heat tolerance, far above PLA or PETG |
| Water absorption | Low compared with PA6 or PA66 | Dimensions drift far less in humid air than PA6 or PA66 |
Two practical consequences follow. First, PA12 is a good default when a part must survive handling, vibration and repeated assembly. Second, it is not a high-stiffness material: if a long, slender part deflects too much, add ribs or increase section depth before reaching for a different material (see the carbon-fibre nylon guide).
Design rules for SLS nylon
| Feature | Rule | Why |
|---|---|---|
| Minimum wall | 0.7 to 1.0 mm | Thinner walls break in cleaning and handling |
| Hollow parts | Add 4 to 5 mm powder escape holes | Loose powder must leave the cavity |
| Large flat, thick sections | Hollow or rib them | Ribbed sections cool evenly and stay flat |
| Mating parts | Clearance 0.3 to 0.5 mm | Matches the stated tolerance |
| Holes | Add 0.1 to 0.3 mm to diameters, or ream | Printed holes come out smaller than drawn |
General rules for all processes are in design for 3D printing, and accuracy is covered in 3D printing tolerances.
Worked example: hollowing a block
A solid 60 x 60 x 60 mm block has a volume of 216 cm³, so it weighs roughly 216 g at about 1 g/cm³. Hollow it with 2 mm walls: the cavity is 56 x 56 x 56 mm = 175.6 cm³, leaving 216 - 175.6 = 40.4 cm³ of nylon, about 40 g. That is an 81% cut in material and weight, and a smaller thermal mass that cools more evenly. It needs at least two escape holes, because one hole alone makes it hard to shake loose powder out. Place them on opposite faces or at the low and high points of the cavity.
Worked example: tolerance on three sizes
| Dimension | 0.3% of size | Applied tolerance (min ±0.3 mm) |
|---|---|---|
| 40 mm | ±0.12 mm | ±0.3 mm (the floor applies) |
| 100 mm | ±0.30 mm | ±0.3 mm |
| 165 mm (full bed width) | ±0.50 mm | ±0.5 mm |
Small features are therefore governed by the floor rather than the percentage. If a press fit must hold better than ±0.3 mm, design it to be reamed or finished after printing, and mark it on the drawing.
PA12 SLS or PA12 FDM?
Both routes use nylon, but they print differently. FDM nylon is built layer by layer from filament and shrinks as it cools, so smaller designs hold shape best and ribs and fillets help larger ones. SLS fuses powder, needs no supports and handles complex geometry better. FDM reaches 1000 mm; SLS stops at 165 x 165 x 300 mm.
| Need | Choose |
|---|---|
| Complex or interlocking geometry, no supports | SLS PA12 |
| Hollow part with internal channels | SLS PA12, with escape holes |
| Part larger than 165 x 165 x 300 mm | FDM nylon, or split the SLS part |
| Smoother surface or finer detail | SLA resin |
| Flexible or rubber-like | TPU in FDM, or flexible photopolymer |
| Lowest cost per part in a batch | SLS, nesting small parts in the powder bed |
Strength, anisotropy and fatigue
SLS PA12 is much closer to isotropic than FDM, but not perfectly so: the Z direction (up through the layers) is usually a little weaker and less ductile than X and Y. For a part that carries a critical load, put the main tensile load in the XY plane where you can. Repeated flexing, as in a living hinge or snap fit, is a good use of the material, but test a sample to the cycle count you need, because fatigue life depends on thickness, radius and surface condition.
Surface, colour and finishing options
Out of the machine, PA12 is matte, off-white to light grey and slightly grainy. Our finishing services include sand blasting, dyeing, painting and threaded inserts. Dyeing penetrates the nylon so scratches do not show a white core; painting suits a visible cosmetic finish. Ask which finishes your geometry accepts, since cavities and fine features can trap media or dye. See the post-processing guide for options by process.
| Goal | Finish to ask about |
|---|---|
| Even matte surface | Sand blasting |
| Black or coloured through-surface | Dyeing |
| Cosmetic colour, branding | Painting |
| Repeatedly assembled screw threads | Threaded inserts instead of printed threads |
| Sealing against liquid or air | Ask an engineer; sintered nylon is slightly porous, so a coating or test is needed |
Frequently asked questions
What is PA12 nylon?
PA12 is a strong, tough engineering nylon. In SLS it is the one material we run, suited to functional and end-use parts.
What is the SLS build volume?
165 x 165 x 300 mm. Larger parts can be split into sections or produced in FDM, which builds up to 1000 × 1000 × 1000 mm.
How accurate is SLS nylon?
±0.3% with a minimum of ±0.3 mm. Flag critical dimensions on the drawing and we check them before dispatch.
Does SLS need supports?
No. The loose powder supports the part during the build, so overhangs and internal features print without support material.
How fast can I get SLS parts?
From 2 calendar days. The quote shows the date for your part, and finishing adds time.
What is the minimum wall thickness for SLS nylon?
Our stated typical minimum is 0.7 to 1.0 mm. Walls that carry load or are tall and unsupported should be thicker, around 1.5 mm or more, so they survive cleaning and handling.
How strong is PA12 compared with PLA or PETG?
Typical published figures put sintered PA12 at about 40 to 50 MPa tensile strength with useful ductility, and heat deflection far above PLA. Its strength is also more uniform between directions than FDM. Check the datasheet for the exact grade.
Can SLS nylon be waterproof?
Sintered nylon is slightly porous, so it is not automatically watertight or airtight. If sealing matters, tell an engineer the pressure and fluid so a coating or a test can be planned.
Get started
Talk to an engineer about your part.
Send us your CAD or describe the problem. We recommend the process, material and finish, and quote with the lead time up front.
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