3D-printed brackets for innovative vehicle project

Kirchheim/Teck, March 20, 2023. A mobile world in which vehicles no longer rely on fossil fuels for propulsion—this is the vision automotive manufacturers and their engineers are pursuing worldwide. One of the German pioneers in this field is Sono Motors with its vehicle-integrated solar technology. The 3D specialists at the BENSELER subsidiary 3D Laser BW GmbH & Co. KG supported Sono Motors in the development of the solar-powered electric passenger car “Sion” by supplying custom-designed brackets used at various positions within the vehicle body.

An electric vehicle that uses every ray of sunshine to charge its battery and generate additional driving power: this innovative idea was realized by Sono Motors’ engineers in Munich with the Solar Electric Vehicle (SEV) Sion. Measuring 4.45 meters in length and 1.83 meters in width, the test vehicles—equipped with solar cells that are visually almost flush with the surface on the hood, fenders, sides, roof, and rear—are able to cover an average of 120 kilometers per week using solar energy alone.

This exciting project, which was discontinued on February 24, 2023, prior to pre-series production, also involved the 3D specialists at 3D Laser BW in Kirchheim/Teck, a subsidiary of the BENSELER Group. For the series-validation vehicles, they supplied 21 different bracket variants that were installed in the vehicle structure of the solar car, which at 1.73 metric tons is lightweight compared to other electric vehicles. These brackets create the connection between the vehicle structure and the plastic exterior components.

Custom manufacturing using metal laser melting

The brackets, custom-designed for their respective installation locations within the vehicle body, were produced using the selective laser melting process. For this purpose, the BENSELER additive manufacturing specialists used the DMP320 metal 3D printer from 3D Systems, featuring a build volume of 273 x 273 x 400 mm. The components were manufactured from austenitic stainless steel powder of alloy 1.4404/316L, which offers excellent corrosion resistance due to its high chromium and molybdenum content combined with a low carbon level. The average build time per build plate was approximately 50 hours.

To ensure quality, the laser melting process is monitored using melt pool monitoring, meaning sensors continuously check the melt pool for correct temperature and potential defects. If irregularities are detected, machine operators can intervene and make corrections.

Precisely matched upstream and downstream processes

Before production begins—as was the case with the Sion project—the CAD data is prepared by BENSELER experts using the additive manufacturing software 3DXpert. This includes not only positioning the components but also designing precisely matched support structures required for the manufacturing process and simulating potential distortion of the brackets.

After completion of the laser melting process, the components are separated from the build plates and the support structures are removed. The required threads are then machined, followed by a final surface finish in accordance with customer specifications. The finished parts are subsequently delivered to the vehicle manufacturer for installation.