In the automotive field we often get requests for parts that are no longer made, parts for vehicle prototypes or very small runs for motorsport. Typical examples are an intake duct with a modified route, a bracket for a new sensor or a broken dashboard clip from an old model. SLS fits this work because the parts are made of polyamide, the same family of materials as many of the plastic parts in a vehicle, and because complex geometries such as curved ducts come out without supports.
Choose the material first by operating temperature. The heat deflection temperature (HDT) at 1.8 MPa, from the Formlabs data sheets, is 46 °C for PA11, 87 °C for PA12, 113 °C for PA12 GF and 178 °C for PA11 CF. At 0.45 MPa the same materials reach 170–188 °C, so a lightly loaded part withstands much more heat than a part under load. HDT is not a continuous operating temperature, so for under-bonnet parts check the actual temperature at the mounting location and leave a margin.
In motorsport the stiffness-to-mass ratio matters, and PA11 CF has the highest stiffness in our range. It warps less during cooling than plain PA11, so it also suits wider parts. For clips and mounts that take vibration, PA11 is more forgiving than PA12. Safety-related parts (braking, steering, structural mounts) should not be replaced with SLS parts without testing and validation by someone who takes responsibility for the result.
Why SLS
- Ducts and curved channels come out in a single piece, with no internal supports to remove.
- Polyamides resist automotive fluids well. In the Formlabs data sheet for PA11, the mass gain after 24 hours is 0.2% in diesel and 0.5% in hydraulic oil.
- The reinforced grades (PA12 GF, PA11 CF) have a higher HDT and are stiffer than PA12.
- Spare parts can be made as single pieces, remodelled from the original, without a mould.
- Mass is low compared with equivalent metal parts, which matters in motorsport.
Parts we often print
- Air ducts for intake, brake cooling and ventilation
- Brackets for sensors, cameras and electronic modules
- Dashboard clips, covers and trim for restorations
- Mounts and guides for wiring harnesses and hoses
- Enclosures for data acquisition electronics
- Adapters for filters, pressure gauges and dashboard instruments
- Mock-ups for checking installation space in prototypes
Design tips
- Choose the material by operating temperature and load. Near the engine PA11 CF or PA12 GF is the usual choice, and in the cabin PA12 or PA11.
- Use metal bushings or inserts in mounting holes in areas with vibration. Nylon creeps slowly under constant clamping load, and the screw loses tension.
- Large ducts can fit on the Fuse X1 (330 × 330 × 565 mm). Long, wide parts can warp during cooling, so add ribs or a stiffening flange.
- PA11 CF has different properties in X and Y, because the fibres align along X. Tell us the main load direction so that we can orient the part.
- If you are modelling from a broken part, also send photos or the dimensions of the parts it mates with. Measurement errors in the model carry straight into the printed part.
The full rules are in the SLS design guide.