Metal additive manufacturing (AM) technology is accelerating industrial development in the automotive sector as shown by the repeated success of French luxury automotive sports car brand Bugatti in achieving consistent function integration and significant performance optimisation of components.
Numerous metal 3D printed functional parts from Bugatti have previously featured in the press, including this very magazine, and all were produced on machines developed and manufactured by German metal AM leader SLM Solutions.
Sparks fly during the dynamic bench testing of a Bugatti brake calliper, the volumetrically largest functional titanium component built with selective laser melting to be tested.
“Proof that additively produced metal components can cope with extreme strength, stiffness and temperature requirements at speeds of over 375 km/h with a braking force of 1.35g and brake disc temperatures up to 1,100°C,” says Frank Götzke, Head of New Technologies at Bugatti.
The component was manufactured in the aerospace alloy Ti6Al4V with Fraunhofer IAPT (formerly Laser Zentrum Nord) and Bionic Production AG on an SLM 500 system featuring four 400W lasers. The calliper test achieved a tensile strength of 1,250 N/mm2 and a material density of over 99.7%.
Bugatti brake calliper testing
Testing the 3D printed brake calliper from Bugatti.
Bugatti utilises selective laser melting not only for lightweighting, but also within the functional scope of its vehicles. A second component, an active spoiler bracket manufactured on an SLM 500, represents this combination aiding the 1,500 hp vehicle to reach speeds of 400 km/h in just 32.6 seconds and bringing it back to a stop in just nine seconds. The active rear spoiler can be adjusted in height and angle, supporting the sophisticated aerodynamics required.
“We always strive for absolute perfection, stylistic as well as technical, as well as considering the perfect synergy of both elements – the tradition of Ettore Bugatti we uphold,” Götzke stated.
Bugatti teamed with Siemens to optimise the bracket for production and reduce the number of iterations needed to optimise for weight and rigidity. Utilising 3D printed titanium with a tensile strength of 1,250 MPa and a material density of over 99.7%, the spoiler bracket was reduced by 5.4 kg, a weight reduction of 53%, but also increased rigidity without sacrificing any functional benefits.
With fewer sparks but no less intrigue, Bugatti has also developed another small bracket with integrated water cooling, which acts an active heat shield to boast a remarkable reduction in transferred heat. The motor bracket has been installed in all series vehicles since the delivery of the first Bugatti Chiron from the supercar manufacturer’s production facility in Molsheim, France.
Bugatti SLM
Additively manufactured spoiler bracket on an SLM 500.
The Chiron, like its predecessor, the Veyron, has two separate water-cooling circuits to keep the component and system temperatures at an acceptable level, even under the most extreme environmental and operating conditions. The high-temperature circuit is used to cool the 1,500 hp W16 engine of the supercar, while the low-temperature circuit ensures that the intake charge cooling temperature remains suitably low. A bypass flow filter of the NT circuit supplies the console while isolating the electronic components from the temperatures of the transmission oil tank. The primary task of the bracket is to engage the gears while opening and closing the two clutches of the 7-speed dual-clutch transmission while including the control unit. As a result, the temperature at the electric motor and at the control unit of the pump when driving through a demanding handling course can be lowered from 130°C to 90°C, a reduction of 40°C. The bracket, which was manufactured in the alloy AlSi10Mg on an SLM 280 Twin, was commissioned by SLM Solutions at Rolf Lenk Werkzeugbau GmbH.
The origin of this cooperation between the Volkswagen subsidiary Bugatti and the SLM Solutions Group AG dates back to the design, calculation and later production of a bionically optimised front axle differential housing at the turn of 2014/2015. Götzke recalls a meeting more or less by chance in the parking lot of the Volkswagen Tor Ost headquarters in Wolfsburg, stating that this was "... a real stroke of luck" that continues today. Ralf Frohwerk, Global Head of Business Development at SLM Solutions, was there from the very beginning as Bugatti’s contact at SLM and emphasises how this chance meeting has resulted in a very trusting cooperation from the outset.
Incidentally, that front axle differential housing was manufactured by Audi AG at its locations in Ingolstadt and Györ on two SLM 280 machines, with the objective of comparing the influencing factors of varying locations on component quality.
Götzke and Frohwerk gave visitors at the last Formnext event in Frankfurt a clear indication as to how this cooperation will grow in the near future as SLM Solutions exhibited a number of large-scale end-use parts on its booth. The exhibition featured eight Bugatti W16 cylinder head covers as a production study for its large-format SLM 800 capabilities which allowed all eight parts to be created in a single construction job with each hood measuring 285 (L) x 65 (W) x 735 (H) mm. When scaling up for even bigger production runs, up to five of these machines can be connected via an SLM Hub to enable fully automated operation, powder handling and unpacking.
