This 3D

ORNL

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In efforts to advance additive manufacturing, a team of researchers, along with inputs from NASA, has 3D-printed a wheel identical to a design used by the space agency for its robotic lunar rover. The process highlights how the technology can be used for specialized parts required for space exploration.

For the team at the Department of Energy’s Oak Ridge National Laboratory (ORNL), the lightweight wheels of the Volatiles Investigating Polar Exploration Rover (VIPER) served as inspiration for their design. NASA hopes to use a mobile robot in 2024 to survey ice and other possible resources near the south pole of the Moon.

Though the wheel won't find use on the actual rover itself, the performance of the printed wheel will be evaluated by NASA in comparison to a conventionally constructed wheel that will be used on the Moon next year.

While permitting design complexity and the customization of material characteristics, additive printing can lower energy consumption, material waste, and lead times.

The Manufacturing Demonstration Facility (MDF) situated at ORNL, which 3D printed the wheel, has been developing the technology for more than ten years for a variety of uses in the industrial, transportation, and clean energy industries.

As far as the production process goes, it included synchronized lasers, a revolving build plate, and a customized 3D printer, which were utilized to precisely melt metal powder into the desired form. Standard metal powder bed systems work in the following steps: They rake a layer of powder over a fixed plate in a machine the size of a cabinet. A layer is then selectively melted by a laser before the plate is gently lowered and the procedure is repeated.

According to Peter Wang, who oversees MDF development of new laser powder bed fusion systems, the printer used for the rover wheel prototype is big enough for a person to enter and is exceptional in its capacity to print substantial items while the stages take place concurrently and constantly. What was also key was "software developed at ORNL to “slice” the wheel design into vertical layers, then balance the workload between the two lasers to print evenly, achieving a high production rate," said a statement by ORNL.

The team says this process increased the production rate, helping deposition occur 50 percent faster. "We’re only scratching the surface of what the system can do. I really think this is going to be the future of laser powder bed printing, especially at large scale and in mass production," said Wang.

A study regarding their work with additive manufacturing was published in the journal Mary Ann Liebert.

The 3D-printed wheel's dimensions stood at around 8 inches in width and 20 inches in circumference, and was made of a nickel-based alloy. According to the team, the additive printing technology used displayed the capacity to print fine geometric details over a big work area, allowing for intricacy in the rim design without raising costs or complicating manufacture.

The four VIPER wheels are set to be used next year; in contrast, they needed several manufacturing procedures and assembly steps. The 50-piece wheel rim of the VIPER is joined at 360 points by rivets. The demanding requirements of the mission necessitated a labor-intensive and sophisticated production procedure.

In contrast, future rovers may instead employ a single printed wheel rim, which took ORNL just 40 hours to create, if NASA testing demonstrates that the 3D-printed prototype is as durable as traditionally constructed wheels.

Researchers said that the additive manufacturing process allowed ORNL and NASA experts to investigate printing precise design elements, including angled sidewalls, a domed form, and wavy tread, in order to boost the rigidity of the wheel. Using conventional manufacturing techniques, it is impossible to include these features in the present VIPER wheel design. Despite permitting a wheel with a more intricate spoke pattern and spoke locking capabilities, 3D printing made the wheel design simpler, cheaper, and easier to assemble.

A limitation to this process is that the 3D-printed wheel is 50 percent heavier than the conventional aluminum VIPER wheel while being created at the same thickness. This is due to the difficulty of using the specialist printer, which can only construct with specific materials (in this case, a nickel-based alloy).

The space agency is set to do extensive testing of the 3D-printed wheel on a rover at one of its facilities in NASA’s Johnson Space Center to evaluate the wheel’s maneuverability, pivoting resistance, sideways slippage, slope climbing, and other performance metrics. If results come out satisfactorily, it is expected to make it to the space agency's rovers very soon.