Audi turns to 3D printing for its Lunar Quattro rover
German automotive company Audi, has turned to 3D printed to optimize and enhance the Lunar Quattro rover which is expected to land on the moon by 2017.
The team Part-Time Scientists is one of the sixteen teams running for the Google Lunar XPrize, a contest that will award 20 million dollars to the first team to land on the moon, travel at least 500 meters and send high definition images back to earth.
The Part-Time Scientists are a Berlin Germany based team of scientists and engineers, To date, the team managed to position themselves amongst the front-runners of the competition and has been awarded 2 Google Lunar XPRIZE milestone prize awards, worth $750,000 . The team consists of around 70 members contributing across 3 continents with a fixed staff of 35 based in Germany with partners as Audi and DLR.
When it comes to manufacturing highly complex-shaped parts displaying low weight and high stiffness, Audi uses 3D printing, Harald Eibisch, an engineer in casting and additive manufacturing technology development at Aud says “3D printing with aluminum makes it possible to produce lightweight parts of almost any shape with a closed shell. The wheel of the Audi lunar quattro has a wall thickness of only a millimeter but displays outstanding strength thanks to its sophisticated design. The material has also been thoroughly tested in the Audi laboratories. We’ve been using alloy AlSi10MgSr in the aluminum castings of our Spaceframe bodies for decades.”
The weight reduction expertise gained in manufacturing the four rings’ production cars is now also benefiting the moon rover. The weight saving achieved by Audi in the Part Time Scientists’ Audi lunar quattro rover comes to around 1.6 kilograms for the four wheels alone. Karsten Becker, the Part Time Scientists’ head of development: “A kilogram of scientific payload in the rover is worth the equivalent of 800,000 euros. Thanks to the weight saving on the wheels, we can put additional scientific material worth 1.28 million euros on board.”
Audi designers revamped the open spoke wheel of the Part Time Scientists’ original Asimov Rover and turned it into a closed system, making it less vulnerable to moon dust. They also increased its size by 22 percent. The greater contact area brings improved climbing capability in fine-grained moon sand dunes. Then, engineers from Audi gear development enhanced the design of the wheel, originally made up of several machined aluminum parts, and tweaked the profile of the treads for better grip. The decisive step in preventing any weight gain was the use of 3D printing technology. Audi engineer Harald Eibisch: “In 3D printing, we convert design data files into a buildable format. We just take the shape of the part’s outer shell and add a millimeter of material. This results in a complex and stable surface on the inside that even the best CAD program can’t achieve. The entire wheel has a wall thickness of only one millimeter. That way, we’ve been able to reduce the weight per wheel by 400 grams.”
Regarding 3D printing applied for automobile production, Eibisch is qutie skeptical, “A single wheel for the Audi lunar quattro costs roughly 3,000 euros and takes a good day and a half to print. At present, aluminum 3D printing is only economical for parts up to the size of a fist, but most of the structural parts in our vehicles are bigger than that".
However, the goal for Audi is clear: “Not in five, but maybe in ten to twenty years, we will be making large-scale structural parts using the 3D printer. The technology opens up fascinating new possibilities for automotive engineers and designers: We will be able to simply print sophisticated structures, integrate functional parts into them that save weight, rapidly change the geometry of cars and so make them more individual. The added value in terms of function, weight and stiff ness will be enormous.”