German automaker BMW Group has won the 2018 Altair Enlighten Award within the Module category for its 2018 BMW i8 Roadster metal 3D printed convertible roof bracket. This innovative component marks the first time a metal 3D-printed part has been used in a series production vehicle.
The Altair Enlighten Award is intended to honor the greatest achievements in vehicle weight savings each year. The award offers nominees the chance to be recognized internationally as a leading figure in the effort to reduce vehicle weight and meet emissions targets. The six Altair Enlighten Award winners were selected from a field of 57 finalists—nearly double the total from last year’s competition.
BMW Group has been a pioneer for the adoption of additive manufacturing technologies within the auto industry. The company is using the technology to quickly develop advanced prototypes at various stages of the design process, as well as investing in 3D printing research and even using 3D printing for final-phase series production. The latest prototype developed with the technology is a roof bracket for the 2018 BMW i8 Roadster.
BMW Group topped 16 other finalists in the Module category with the first 3D printed metal component used in a production series vehicle, which captured a 44% component weight savings on the 2018 BMW i8 Roadster. Produced with Selective Laser Melting (SLM) technology without needing any support structures, it was also the first time a topology-optimized design has been translated nearly 1:1 into a series production vehicle to capture weight savings and tenfold stiffness increase.
“When the judges looked at this part, we said, ‘this is the tip of the iceberg for manufacturing,’” said Richard Yen, Altair senior vice president for global automotive and industry and one of a team of judges for the award across industry. “What BMW did is get this done without support,” said Yen. “Now they can print one batch at a time for mass production, They can print more than 600 of these brackets in one batch.”
Maximilian Meixlsperger, the head of metal additive manufacturing at BMW, had spent ten years tinkering with the design for a roof bracket before implementing SLS 3D printing technology. In order to keep the soft top mechanism nice and compact, BMW decided to go big, producing geometric bracing parts that are topologically optimized, and getting seriously innovative in the manufacturing process.
The metal 3D-printed bracket attaches the convertible roof cover to a spring-loaded hinge, enabling the roof to fold and unfold without the need for additional noise-reduction measures such as rubber dampers or a stronger (heavier) spring and drive. The part needed to lift, push and pull the weight of the roof, requiring a complex sculptural structure that was impossible to cast. BMW’s designers and engineers used topology optimization software to input specs like the weight of the load they needed to move and the space they have, and the software generated a 'load path', a design that distributes the load to minimize the amount of material required in the part.
The component is also 10 times stiffer than the initially planned, but not sufficiently stiff, component made using injection molding from PA6GF30. The 3D-printed bracket also offers a cost benefit compared to a magnesium die-casting alternative.
The results speak for themselves
The new i8 Roadster’s soft-top folds vertically in a Z geometry, effectively leaving 92 litres of cargo space when stowed into the “roof box” behind the driver. And that’s on top of the 88 litre boot space behind the mid-engine sports car.
“We were honored to receive the Altair Enlighten Award this year and would like to thank the judges for recognizing the efforts of the team that worked on the i8,” said Maximilian Meixlsperger, Head of Additive Manufacturing Metal at BMW Group. “It’s clear that additive manufacturing has huge lightweight potential for vehicle designers when combined with the power of optimization technologies. Getting a 3D printed part onto a mass produced vehicle would have been unheard of until very recently but with this success, we have an opportunity to make the process part of our standard design and manufacturing approach.”