Porsche 3D prints sporty EV drive housing
Lighter, stronger, and cooler than previously cast assembly Metal Tech News – December 23, 2020
Last updated 12/22/2020 at 3:46pm
Porsche has utilized metal 3D printing to produce a complete electric motor and gearbox housing that is lighter, stronger, and more efficient than the traditional cast housings used in its sportscars.
"This proves that additive manufacturing with all its advantages is also suitable for larger and highly-stressed components in electric sports cars," said Falk Heilfort, project manager in the powertrain advance development department at Porsche Development Centre in Weissach, Germany.
Despite the strength-to-weight ratio advantages of this 3D printed electric drive housing, Porsche is not yet ready to scale up production of this additively manufactured part. Instead, the German automaker sees the potential of small-scale manufacturing of the optimized electric drive offering its advantages to a limited-edition super sports car.
Laser melt fusion process, which uses a laser beam to heat and melt high-purity aluminum alloy powder according to the part design, was used to print the gearbox one layer at a time. This layer-by-layer manufacturing process offered Porsche engineers multiple design advantages that improved the performance and integrity of the drive housing.
These benefits begin at the drawing board. With the ability to upload design data from a computer directly to a printer, and without the need to build specialty tools to create the prototype design, Porsche says no other manufacturing process offers a wider array of possibilities or quicker implementation than 3D printing.
"We were able to expand and improve our software solutions and methods for creating such parts and are now able to virtually implement them in a very short space of time," said Sebastian Wachter, specialist in design methodology and topology optimization at Porsche.
The layer-by-layer printing process also opens up new design advantages over casting the parts.
One of the most important benefits realized in printing the electric drive housing is the ability to print lattice structures that decreased its weight by roughly 40%, while at the same time improving its strength, and performance. The lighter housing reduced the weight of the overall electric motor-gearbox unit by 10%.
Despite a continuous wall thickness of only 1.5 millimeters (less than 1/16 of an inch), Porsche says the stiffness between the electric motor and the gearbox was increased by 100% due to the lattice structures. This honeycomb inspired structure also reduces the oscillations of the thin housing walls, which considerably improves the acoustics of the drive.
Another advantage of additive manufacturing is the fact that numerous associated parts that would need to be manufactured separately and then bolted together can be integrated into a single printable design. This considerably reduces the time it takes to assemble the parts and improves the form and function of the final product.
In the case of the 3D printed electric drive, a two-speed gearbox was integrated with the motor housing for use on the front axle of a sports car.
"Our goal was to develop an electric drive with the potential for additive manufacturing, at the same time integrating as many functions and parts as possible in the drive housing, saving weight and optimizing the structure," said Heilfort.
Porsche says the resultant 3D printed electric motor-gearbox unit, which passed all the company's quality and stress tests without any problems, met this objective.
The integration of parts made the drive unit more compact, significantly improved the drive package, and eliminated 40 steps from the assembly process. As an added bonus, the integration of the gearbox heat exchanger improves the cooling of the drive, a basic requirement for further increases in performance.
While the 3D printed electric drive housing further demonstrates the potential of additive manufacturing for Porsche, for now the company does not see this emerging technology immediately replacing traditional casting and assembly for large-scale production. The German automaker does, however, see additive manufacturing offering some exciting new opportunities for the company and its customers.
In addition to agile development and flexible production for its design team, Porsche sees the potential to use 3D printing to create small batches of specialty parts for limited edition production models and race cars.
For its customers, the German automaker sees the potential to 3D print customizations and spare parts for their Porsches. This could mean that Porsche dealers of the future may not need to stock or order many of its parts – just keep an inventory of 3D designs and various powders to print the parts and accessories that meet customer's needs and desires.