Spraytime

On November 7, ITSA members were welcomed to Florida International University’s (FIU) Cold Spray and Rapid Deposition (ColRAD) laboratory in Miami, Fla., for a facility tour and to learn about the school’s research and development initiatives, especially those related to additive manufacturing (AM).

Additive manufacturing has rapidly evolved over the last few decades, transforming industries by enabling more efficient production, customization, and material use. Among the various additive manufacturing techniques, wire-arc directed energy deposition (WDED) stands out for its ability to build large, complex metal components with high deposition rates. WDED uses an electric arc as the heat source and metal wire as the feedstock, fusing layers of material to create intricate geometries. As the demand for AM technologies continues to grow, WDED has gained attention not only for its application in industries like aerospace, automotive, and defense but also for its unique potential to reduce material waste and manufacturing lead times due to supply chain challenges. FIU has emerged as a key player in this field, with its state-of-the-art WDED facility pushing the boundaries of large-scale additive manufacturing research and development at its ColRAD laboratory. The following explores the capabilities of FIU’s WDED facility, from the advanced equipment and sensors to the imaging technologies that allow for precise process control. This article highlights parts manufactured at the facility and ongoing efforts to expand research and workforce development initiatives.

Integration of Equipment, Sensors, and Software for WDED Technology

At the heart of FIU’s WDED facility is a specialized robotic cell equipped with an ABB IRB 2600 robot, which has a capacity of 20 kg (44.09 lb) and a reach of 1.65 m (5.41 ft) (Fig. 1A). The robot’s six degrees of freedom coupled with two additional degrees of the turntable of capacity 750 kg (1653.47 lb) enable intricate movements and large build volumes, ensuring that large additively manufactured parts with complex geometries can be built with exceptional accuracy (Fig. 1B). Central to the system is the Fronius TPS 400i cold metal transfer welding machine capable of depositing wires from 1.1 to 1.6 mm (3.61 to 5.25 ft) in diameter constituted of various compositions, such as aluminum alloys, steels, and novel materials, such as high entropy alloys. This welding machine delivers the necessary energy and material for the deposition process, which, paired with the robot, allows for high-quality builds at an impressive rate (Figs. 1C, D), making it ideal for producing large-scale metal components.

Industry-standard software solutions support the design and manufacturing process. This includes SolidWorks for 3D modeling and topology optimization, ADAXIS for multiaxis non-planar slicing and post-processing, and Siemens NX for streamlining automation from CAD to additive manufacturing simulations (Fig. 1E). These programs enable seamless transition from digital designs to physical parts, ensuring precision in every layer deposited. Efforts are underway to construct digital twins to replicate the complete physical asset of WDED deposition, robotics, and materials that enhance the quality of manufactured parts. Integrating design software with advanced robotic technology allows for rapid prototyping and efficient parts production with minimal material waste (Figs. 1F, G).

To enhance process control, the facility uses thermal sensors for real-time temperature monitoring up to 1200°C (2192°F). These sensors are embedded in the deposited parts and the substrates, allowing for precise control over thermal conditions during the build process (Fig. 2A, B). By closely monitoring temperature variations, researchers can adjust processing parameters quickly, leading to better material properties and overall part quality. These capabilities are further enhanced by advanced imaging systems that provide deeper insight into the process.

High-Resolution Imaging Capabilities and Material Studies

The equipment at FIU’s WDED facility is complemented by a suite of imaging tools, which provide critical insights into the deposition process and the resulting material properties. A Blackmagic high-resolution 6K camera is used for imaging the wire-arc deposition process. Additionally, an i-SPEED 7 Series high-speed camera is used to understand solidification mechanisms during bead formation. This camera can acquire up to 1 million frames per second, capturing minute details during the build, allowing researchers to observe the deposition arc, wire feed, and material flow with unmatched clarity. The footage not only aids in identifying potential process anomalies but also serves as a valuable tool for refining and optimizing future builds. The facility also employs a FLIR thermal camera for temperature monitoring from ambient to 2000°C (3632°F) that provides thermal maps of the part being built, allowing researchers to track temperature distribution across the deposited layers (Figs. 2C, D). Temperature distribution information is essential for controlling cooling rates and preventing unwanted thermal effects like cracking or warping. When combined with the data from embedded thermocouples, the thermal camera enables precise heat management throughout the entire process, ensuring uniformity and consistency in part quality.

One of the standout materials being investigated at ColRAD is commercially pure titanium, a highly sought-after material in industries such as marine, aerospace, and biomedical engineering. Single-phase titanium parts with excellent microstructure (Fig. 2E) and mechanical performance of up to 80% of that of conventionally cast titanium demonstrate the capability of WDED to manufacture high-quality components. Currently, ColRAD is studying the deposition of novel iron-based cored wires for manufacturing bulk HEA large-scale components. Novel microstructures with heterogeneous precipitation are observed. These successes pave the way for further exploration into more advanced alloys and complex materials.

Upcoming Expansion and Workforce Development

The WDED facility at FIU has successfully manufactured a range of metal components, leveraging the versatility of wire-arc technology. Among the notable achievements are aluminum and steel parts and the previously mentioned titanium components. These parts are designed for industries that require lightweight yet durable materials, such as aerospace and automotive, where the ability to customize designs and reduce material waste provides a significant competitive advantage. FIU is poised for an exciting expansion of its WDED capabilities. Plans are in place to integrate a laser-based WDED instrument where the 450 nm wavelength blue light brings in improved energy absorption and printing efficiency across the metallic alloy spectrum. The introduction of this cutting-edge technology will allow for greater control over material properties and expand the range of metals and alloys that can be used in the manufacturing process. This expansion will significantly increase ColRAD’s capacity for research and development, positioning FIU at the forefront of advanced manufacturing technologies. In parallel with these technical advancements, FIU has made significant strides in workforce development. Recognizing the growing demand for skilled professionals in additive manufacturing, the facility offers hands-on training programs that expose students to real-world applications of WDED technology. A particularly inspiring success story is that of a student who began as a high school summer researcher at FIU. Starting with introductory training in WDED, this student transitioned into an undergraduate research role focused on wire-arc additive manufacturing. After gaining significant experience, the student can manufacture WDED parts (Fig. 2F) independently, showcasing the facility’s ability to nurture talent from an early stage and develop the next generation of STEM experts in this field of additive manufacturing.

Conclusion

Upcoming expansions at FIU, including the integration of laser-based instruments, will further enhance the precision and scope of the research. At the same time, ColRAD’s commitment to workforce development equips the next generation of skilled professionals with the expertise to drive the future of this technology.

References

Palacios, B., et al. 2024. Role of crystalline orientations and additive layers on the bulk tensile response of wire-arc directed energy deposited (WDED) single phase titanium. Materials Science and Engineering: A 911(9): 146921.

Mohammed, S. M. A. K. et al. 2023. Exploring the potential of wire fed direct energy deposition of aluminum-boron nitride nanotube composite: microstructural evolution and mechanical properties. Advanced Engineering Materials 25(20): 2300770.

Paul, T., et al. Aluminum boron nitride nanotube composites and methods of manufacturing the same. U.S. Patent US 11780023B2, filed Dec. 14, 2022, and issued Oct 10, 2023.

Palacios, B., et al. 2023. Role of structural hierarchy on mechanics and electrochemistry of wire arc additive manufactured (WAAM) single phase titanium. Journal of Manufacturing Processes 93(5): 239-249.

TANAJI PAUL (tpaul@fiu.edu), is a research assistant professor, TYLER DOLMETSCH is a research scientist, and ARVIND AGARWAL is a distinguished university professor at Cold Spray and Rapid Deposition Laboratory (ColRAD), Florida International University, Miami, Fla.