SAN FRANCISCO — One of two satellite fuel tank simulators rapid prototyping specialist RedEye built for Lockheed Martin Space Systems this past winter was the largest part the firm ever produced with its 3-D printers. Within weeks of delivery, however, Lockheed Martin Space Systems asked RedEye to assist with another project.
“I can’t give details but there’s definitely interest in large parts,” Joel Smith, aerospace and defense strategic account manager for RedEye, a business unit of Minneapolis-based Stratasys Ltd.
As additive manufacturing matures, space-related components produced with various types of 3-D printers continue to grow in size and complexity. The larger of the two fuel tank simulators RedEye built for Lockheed Martin in December and January was more than 2 meters long. RedEye built the simulator, which Lockheed Martin needed to conduct form, fit and function tests on a new satellite design, with 10 polycarbonate pieces that were printed independently and bonded together. RedEye built the smaller, 1.2-meter simulator in six pieces.
Despite that complexity, RedEye was able to complete the job in approximately three months, or half the time Lockheed Martin anticipated for traditional manufacturing techniques. In addition, the 3-D printed fuel tank simulators are significantly cheaper. “Based on the quotes they had received, they were looking at around $250,000 for traditional manufacturing,” Smith said. “We were able to come in at about half the cost of machining.”
Those cost and time savings have made 3-D printing increasingly popular for space-related applications. Although NASA has used additive manufacturing to produce models and prototypes for years, the technology is now being used to produce key metal components of high-performance aerospace systems.
“At some point recently, we passed the tipping point,” said John Vickers, assistant manager for the materials processing laboratory at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Now, additive technology is completely accepted.”
Engineers at NASA Marshall are producing liquid rocket engine components with selective laser melting, an additive manufacturing technique that uses a laser beam to melt layers of a nickel-chromium alloy powder in a pattern determined by a computer-aided design.
“We can do things at a much lower cost and faster schedule,” Vickers said. “It also allows us to design fast, build fast, test fast.”
In the past, it took years to design, build and test a new liquid rocket engine. “Now, it takes weeks or months,” Vickers said. “That offers endless possibilities for new ways to design rocket engines.”
To date, NASA Marshall engineers have used selective laser melting to build components based on the design of conventional parts. Next summer, they plan to begin experimenting with designs created specifically to take advantage of the unique characteristics of additive manufacturing, Vickers said.
NASA also is beginning to experiment with different metal alloys. “Can additive manufacturing be used for copper alloys?” asked Michael Gazarik, associate administrator of NASA’s Space Technology Mission Directorate. “We think it can, which would broaden the number of possible parts and components we could make.”
As NASA officials look at new applications for additive manufacturing, they are scrutinizing components produced in this manner to ensure the parts meet the space agency’s stringent requirements. Fuel injectors, for example, must withstand extremely high temperatures. Based on early indications, selective laser melting is producing reliable parts, but “we have to continue to test, evaluate and measure,” Gazarik said.
That caution extends to the plastic parts that will be produced on the international space station with a 3-D printer by Made in Space. NASA plans to bring parts produced by the space-based printer back to Earth for examination and evaluation, Gazarik said.
The printer “passed all final NASA tests and has been deemed flight-ready,” Grant Lowery, marketing manager for Mountain View, California-based Made in Space, said by email. It is scheduled to travel to the international space station in August on a Space Exploration Technologies Corp. Falcon 9 flight from Cape Canaveral Air Station, Florida. “The space station crew is very excited to begin printing things they need in space,” Gazarik said.
As space agency officials look ahead, they see additional applications for additive manufacturing. “In the future, when the nation decides to build a large-scale rocket engine, this technology along with other advanced manufacturing technologies will be enabling because it will improve capability and lower cost,” Vickers said.
Eventually, NASA may even find ways to use planetary regolith as a key ingredient in additive manufacturing. “One problem for space exploration is mass,” Gazarik said. “If you can’t take everything you need to another planet, you may be able to print habitats or other structures using the regolith.”