It is less than four weeks since Romain Dumas and the ID R Pikes Peak set a new all-time record of 7:57.148 minutes for the Pikes Peak International Hill Climb. For the Volkswagen Motorsport engineers, the race against the clock to design the ground-breaking vehicle lasted far longer – about eight months.
This is an extremely short period in motor racing terms, yet this is all the technicians were given to develop Volkswagen’s first fully-electric racing car. The fact that they passed this test was partly down to the innovative methods used during the test and development phase.
“When we were in the wind tunnel with the 1:2 scale model of the ID R Pikes Peak, we gained a lot of time by using 3D printing,” explains Dr Benjamin Ahrenholz, head of calculation and simulation at Volkswagen Motorsport.
Based on his notes, the aerodynamics experts tested several hundred different configurations for the chassis details of the electric racing car. “We made about 2,000 individual parts for the wind tunnel model in the 3D printer, sometimes with several printers working at the same time,” Ahrenholz adds.
These parts were available to the team within just a few days. “In the case of conventional manufacturing, such as with carbon fiber, we would have had to wait several days or weeks,” Ahrenholz says. Days that, given the time pressure, the engineers simply did not have, especially as the manufacture of carbon-fiber parts requires intricate and expensive mold construction.
A further advantage of the three-dimensional printing process is the ability to manufacture individual items. Technical possibilities meant that the 3D printing components used during the development phase for the ID R Pikes Peak could have an edge length of no greater than about 50cm.
“An example of the kind of parts that were printed is the lamellar upper cover on the front wheelhouses,” says Ahrenholz. “On the other hand, we made the ID R Pikes Peak’s big rear wing from aluminum on the 1:2 scale model.” The spectrum ranged from a bracket just a few centimeters in size for a sensor, to complex channels supplying batteries and brakes with cool air.
As 3D printers process comparatively soft, thermoplastic polymer plastic, components manufactured in this way cannot withstand great mechanical loads. “This only plays a minor role in the wind tunnel,” Ahrenholz explains.
Only the parts determined to be ideal during the test phase were then made of carbon-fiber composite or metal. Occasionally, the engineers were also able to use the 3D printing products to bridge the time until the final product was delivered. “This way we did not have to suspend testing just because a certain part was not yet ready – for example, a cover for the batteries’ power electronics,” Ahrenholz recalls.
Some of the components made in the 3D printing process did indeed find their way into the race car itself. These were exclusively small parts, the shape of which would have been very complicated to manufacture using other manufacturing methods, such as casting or laminating, and the dimensions of which did not have to adhere to extremely low tolerances.
The plastic used in the 3D printing process is heated, as it must be viscous in order to be processed in the printer nozzles. Parts produced in this manner shrink slightly when they cool, meaning that the final dimensions cannot be defined 100% accurately, depending on the printing procedure.
For this reason, the only parts from the 3D printer to be used on the ID R Pikes Peak during its record-breaking run were auxiliary components like brackets for cables and switches. But even they played their part in the overall concept of the car.