A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 3 2 1 allowed UC to do much more. Because metals were not melting, many of the metallurgical issues found in fusion welding could be avoided. As a result, UC was well suited for laminating dissimilar metals to engineer metal parts requiring customized engineering properties. In another example of bonding dissimilar metals, gradients of aluminum and titanium were created for ballistic applications that allow designers to vary the properties of the armor at different depths throughout the thickness. Bonding dissimilar metals led to a series of innovative lightweight armor products. In addition, because the bonded metals do not get hot, UC allowed engineers to embed electronics into solid metal parts. This ability led to real-time vehicle health monitoring applications, including battery health, operator performance, asset tracking, safety, and condition-based maintenance. By combining its embedded predictive and diagnostics capabilities with wired and wireless smart sensors, Solidica enabled new and innovative system health monitoring applications. In 2007, Solidica partnered with EWI in Columbus, Ohio, a 501(c)(3) research organization with expertise in ultrasonic system design, to increase the power in the ultrasonic welding head. During a four-year development program, the team increased the power delivery levels of the ultrasonic horn from 2 kW to over 9 kW. The power boost allowed UC to be used on harder materials such as steel and nickel alloys while simultaneously increasing the deposition rate of the process. The culmination of the research was a new 9 kW systemwith a printing envelope of 6 x 6 x 3 ft, enabling the creation of large metal parts (Fig. 2). ULTRASONIC AM In 2011, Solidica and EWI consolidated their intellectual property into a new joint venture named Fabrisonic LLC, and rebranded UC as ultrasonic additive manufacturing (UAM) in line with the explosion of the 3D printing industry. Over the past decade, Fabrisonic has continued to improve the capabilities of UAM and grow the installed user base. Fabrisonic developed as a hybrid organization providing both 3D printing services using UAM and selling a line of metal 3D printers via the SonicLayer line of CNC-based systems (SonicLayer 1200, 1600, 4000, and 7200). Fabrisonic immediately found success in printing 3D multi-metal heat exchangers for the aerospace industry. Traditionally, aluminum and copper components with complex internal geometries (cold plates, radiators, and RF waveguides) are produced as brazed assemblies. These complex assemblies pose many manufacturing issues that typically lead to a low first-pass yield. As another option, UAM can be used to 3D print all grades of aluminum and copper. With this hybrid manufacturing process, designers can reliably create interwoven passageways within a part that is printed in a single step. Using dissimilar metals and complex internal passages has enabled engineers to produce heat exchangers with the same mass but twice the thermal performance of traditional brazed assemblies (Fig. 3). UAM is increasingly being adopted in electrification. Fusion-based additive manufacturing processes have allowed manufacturers to create novel geometric solutions not possible with traditional manufacturing. Alternatively, solid-state 3D metal printing allows for freedom of geometry and material not possible with either subtractive (e.g., CNC) or additive (e.g., powder bed fusion) techniques. UAM designs often allow for denser packaging, higher performance, and taking advantage of engineered material properties. UAM also excels at mixed metal Fig. 2 — SonicLayer 7200 UAM systemwith a build envelope of 6 x 6 ft. Fig. 3 — (a) Multi-metal chemical mixing vessel with embedded temperature sensor; and (b) aerospace heat exchanger. (a) (b)