Something new in manufacturing that has applications for NASA spacecraft is being transferred to the private sector to help developing many industries in our planet.
A burst water main is always expensive and messy, but a pipe that fails in space can be mission-ending. That’s why NASA technologists work hard to make hardware as reliable as possible. Sometimes that means scrapping the old way of doing things and experimenting with a brand-new material – or fabrication process.
This challenge spurred Scott Roberts, a technologist at NASA’s Jet Propulsion Laboratory in Southern California, to turn to a new kind of welding in the AM Industry. The private sector was already using this method, called ultrasonic additive manufacturing. With some additional innovation, Roberts thought it could be used to improve reliability in heat exchangers, a crucial component of any spacecraft.
The problems I’m working on don’t solve one problem for one mission,…they’re going to solve a class of problems for both NASA and industry.”
-Scott Roberts, technologist at NASA
What’s the relation between additive manufacturing and pipes?
Extreme temperatures is a problem in aerospace, it can vary by hundreds of degrees. Heat exchangers help maintain the temperature inside a spacecraft by removing excess heat or drawing in more. Traditionally, these devices include a long, snaking pipe attached to a metal plate with brackets and epoxy.
With UAM, however, the entire device can be crafted as a single piece. Small Business Innovation Research (SBIR) funding provided by JPL made it possible for Roberts to work with Columbus, Ohio-based Fabrisonic LLC on a new heat exchanger design. As a subcontractor for Sheridan Solutions LLC, Fabrisonic started with an existing process that builds up multiple thin layers of metal by fusing them together with high-frequency vibrations. To create the heat exchanger, a curved channel is carved into the layered metal and then enclosed under additional layers.
The new design replaces dozens of small parts and joints that could fail during a long-term mission or under extreme conditions on Earth.
Why vibrations fuse metal?
Ultrasonic welding uses sound and friction to create a solid-state bond between layers of metal. It begins with a thin foil pressed onto another metal component such as a base plate. Constant pressure and ultrasonic vibrations cause friction between the facing sides, creating a shearing motion that raises temperatures and removes surface oxides, allowing direct contact of pure metal to pure metal. The result is a solid-state atomic bond that welds layers of metal together. Even layers of different metal can be bonded into a single piece.
Relatively little heat is required because the bonding temperature for metals is significantly below their melting temperature. Fabrisonic can quickly piece together layers as large as six feet square, making it possible to create a part with a complex geometry in a matter of days, rather than the months required by traditional fabrication practices. This shortens the development cycle for a spacecraft or speeds the manufacture of parts to commercialize.
Combining new metals
The protection of electronic components from intense space radiation that can destroy them is challenging when everything on a spacecraft needs to be lightweight. It’s one problem Roberts is trying to solve using new materials. Additional SBIR funding provided by NASA’s Langley Research Center in Hampton, Virginia, paid for Fabrisonic to add layers of the radiation-resistant metal tantalum in the middle of aluminum spacecraft parts.
Unlike other forms of welding, UAM won’t cause the different metals to liquefy and mix together. Engineers can rely on the properties of each metal to remain constant and perform as expected, said Mark Norfolk, president of Fabrisonic. This quality demonstrated that NASA could realize its goal of combining the aluminum with tantalum.
Sensors inside metal
New fiber optic sensors can detect metal strain or weaknesses and predict possible failures before they occur. But metal manufactured using traditional methods can only support these sensors on the exterior of the part. In an attempt to embed them, the heat used in the manufacturing process would destroy the delicate devices.
What if you want to print small parts yourself?
NASA’s Marshall Space Flight Center in Huntsville, Alabama, meanwhile, funded Fabrisonic’s exploration of the use of advanced metallic materials and UAM for in-space manufacturing, this time as a subcontractor on Phase I and II SBIR contracts with a machine automation company called Ultra Tech Machinery Inc. The agency’s engineers worked with Fabrisonic to develop a small UAM printer for use on the space station. The company had a design ready but didn’t know if it would work. NASA specifications made it possible to build, test, and refine the most important component of the printer – the weld head. This part transfers the ultrasonic vibration onto the metal tape used in the printer.
Miniaturizing this technology for fabricating smaller parts offers a more cost-effective approach than using an industrial UAM process. Commercial sales of the company’s resulting SonicLayer 1200 printer have generated $1 million in revenue, with one customer producing over 70,000 parts in-house.
Commercial success has allowed the company to develop a diverse customer base and double in size, growing to 12 employees.
Without SBIR and other government support, Fabrisonic may not have crossed the chasm between startup and commercial success,(…), It has enabled important research and developments. It makes critical information available, such as materials characterization data and case studies that help spread technology.”
– Mark Norfolk, President at Fabrisonic
NASA has a long history of transferring technology to the private sector. The agency’s Spinoff publication profiles NASA technologies that have transformed into commercial products and services, demonstrating the broader benefits of America’s investment in its space program. Spinoff is a publication of the Technology Transfer program in NASA’s Space Technology Mission Directorate.
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Norfolk, Mark, Ultrasonic Welding Makes Parts for NASA Missions, Commercial Industry, https://www.jpl.nasa.gov/news/ultrasonic-welding-makes-parts-for-nasa-missions-commercial-industry published on May 28 2021, re-edited and published by João Andrade on Jun10 2021;
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