Additive manufacturing lets companies think “outside the box.” Engineers can now start to look at a part without restrictions on size, shape or material. Instead of taking 15 different CNC milled parts and brazing them together, these companies have reimagined the part entirely—to be built as one part.
On top of that, adoption of additive manufacturing has led to a new generation of high-performance parts in the aerospace/defense sector, such as Lockheed Martin’s spherical fuel tanks for satellites. And some parts, such as the GE fuel nozzle currently in production, sport designs that could not be considered with conventional manufacturing.
In the last five years, a majority of the 3D-printed production parts coming out of the sector has been made from polymers. Polymer technologies have been around significantly longer than metal additive manufacturing and, as a result, are more mature in the MRL (manufacturing readiness level) spectrum. Commercial and military vehicles are now filled with 3D-printed plastic ducts, cable stays, and hose routing systems. However, in the last 18 months Fabrisonic has seen an accelerated shift to 3D printing of metal production parts. Both airframers and first-tier aerospace suppliers have been among the new adopters.
Fabrisonic, which provides 3D metal printing services in a wide range of metals, is adding a new option to the mix: Its ultrasonic additive manufacturing (UAM) process, brought to market in 2015, harnesses sound waves to merge layers of metal foil in a process that requires no melting. This allows for the construction of parts previously thought impossible, such as aluminum parts with embedding cooling and embedded sensors for NASA and microchannel heat exchangers for Oak Ridge National Lab.
Building in the solid state enables Fabrisonic to join dissimilar metals and other thermally sensitive materials, such as electronics.
For example, in aluminum, the peak temperatures are below 250°F (121°C), which allows 3D printing without changing the base material properties. The low temperature allows bonding combinations of metals such as Fe-Al, Al-Ti, Ta-Fe, and Cu-Al without forming brittle intermetallics.
Due to the low temperature bond, UAM allows electronics and sensors to be embedded in solid blocks of metal without damage. Electronics can include microprocessors, plastic connectors, USB ports, thermocouples, fiber optics and Bragg gratings.
One way this is playing out is in the placement of sensors throughout a metal structure, to provide constant health and damage reports. A structure with an embedded fiber optic strain sensor “knows” its own health and can actually record cumulative damage to a component over time.
Another way the aerospace sector is leveraging this capability is through printing dissimilar metals in a single part. With UAM, dissimilar metals can be bonded without creating brittle intermetallics, and that makes it possible for Fabrisonic to print custom materials for a particular property. For instance, alternating layers of aluminum and titanium can be combined to produce an armor product that is lightweight but has sufficient ballistic performance.
Fabrisonic’s solid state welding approach also makes it possible to 3D-print complex internal shapes, such as heat exchangers. UAM enables component designs that have never been considered before. A part can be printed in one sitting that has (A) embedded channels for thermal management (B) metal matrix composites for strength (C) electronics and sensors for control and (D) multiple metals to optimize strength spatially. One part covering many functions will let manufacturers make lighter, more capable products.