On a machine that otherwise works, a plastic clip, cover, gear or bracket can break. If the manufacturer no longer supplies the part, only sells it as part of a whole assembly or has a long delivery time, the part can be SLS printed in polyamide, the same family of materials that many plastic parts in vehicles and equipment are made of.
If you have a 3D model of the part, we print it directly. If you don't, we make one: we model the part in CAD from photos, dimensions or a drawing, or 3D scan the original part and rebuild it. Worn or broken parts are rebuilt to their intended shape, and the assembly dimensions are measured with a caliper. You also receive the STEP file, so the next piece can be ordered without modelling it again.
Choose the material by the working conditions. PA12 suits most covers, housings and brackets, and PA11 copes better with impacts and with clips that flex a lot. Near heat sources the heat deflection temperature (HDT at 1.8 MPa) matters, which is 87 °C for PA12, 113 °C for PA12 GF and 178 °C for PA11 CF, according to the Formlabs data sheets. For seals, pads and elastic parts, TPU 90A is used.
Why SLS
- No mould is needed, so a single part is as simple to produce as a small batch.
- Parts print without supports, so shapes with channels, ribs or cavities come out in one piece.
- Polyamides resist oils and fuels well in normal contact. In the Formlabs 24-hour test, PA12 gained 0.4% in mass in diesel.
- Once modelled, the part can be reordered from the same file, with the same orientation and the same dimensions.
- The part can be improved over the original, for example with a thicker wall where it broke.
Parts we often print
- Clips, catches and covers for household appliances
- Gears and rollers for lightly loaded mechanisms
- Knobs, handles and covers for industrial machines
- Covers, guides and guards for agricultural machinery
- Brackets, clips and trim for vehicles that are no longer made
- Housings and covers for sensors and control boxes
- Seals and pads in TPU 90A
Design tips
- Send photos from several sides, with a ruler or a caliper visible in the picture, and the main dimensions. For parts that mate with others, the dimensions of the mating part matter just as much.
- If the original part broke at a thin section, tell us. That area can be thickened or stiffened with a rib, as long as it doesn't affect assembly.
- For screws that are tightened and undone often, use heat-set brass threaded inserts instead of printed threads.
- Holes for shafts, pins or bearings are designed slightly undersize and reamed after printing, as Formlabs recommends.
- Safety-related parts (braking, steering, structural mounts, machine guards) should not be replaced with SLS parts without testing and validation by someone who takes responsibility for the result.
The full rules are in the SLS design guide.