Bugatti is the crown jewel of the Volkswagen Group. But the maker of the $3 million Chiron also serves as one of the group's technical development laboratory, alongside Porsche's powertrain and Lamborghini's composite departments, pushing new technologies towards production. Bugatti's latest development is the world's first 3D-printed titanium brake caliper, created by a quartet of 400-watt lasers.
As you'd expect, the Chiron already comes with the most powerful brakes ever bolted to a production car, featuring the world's largest calipers with eight titanium pistons at the front and six at the rear. But while these forged aluminum alloy calipers weigh almost 11 lbs., the new 3D-printed prototypes are 40 percent lighter, as well as considerably stronger, thanks to being made of Ti₆Al₄V titanium alloy.
This new unit is is 41 cm long, 21 cm wide and 13.6 cm high, weighing just 6.4 lbs. More importantly, it has a tensile strength of 1,250 N/mm2, meaning that a force of slightly more than 275 lbs. can be applied to a square millimeter of this titanium alloy without the material rupturing.
Designed with the help of Laser Zentrum Nord of Hamburg in just three month, Bugatti's caliper takes a total of 45 hours to print, during which 2213 layers of titanium powder get melted together by the lasers. Following the completion of the final layer, the remaining titanium powder is removed from the chamber, cleaned and preserved for reuse in a closed loop. What remains in the chamber is a brake caliper complete with supporting structure which maintains its shape until it has received stabilizing heat treatment and reached its final strength. What heat treatment? I'm glad you asked!
The calipers go into a furnace that starts at 1292°F, falling to 212°F during the process in order to eliminate residual stress and to ensure dimensional stability. Finally, the supporting structures are removed and the component is separated from the tray. Then, the surface is smoothed in a combined mechanical, physical and chemical process which drastically improves its fatigue strength. Finally, the contours of functional surfaces, such as the piston surfaces or threads, are machined in a five-axis milling machine which takes another 11 hours to complete its work. The result is a delicately shaped component with wall thicknesses between a minimum of only 1mm and a maximum of 4mm.
That's crazy, but Bugatti isn't done yet. As the team proudly points out, while they're working on shortening the titanium calipers' production time, they've also come up with the longest aluminum component ever made by 3D printing: a 24.8-inch-long lightweight aluminum windshield wiper arm, weighing just 0.88 lbs.
And that is why the Chiron is a $3 million car, delivery included.