Cold Spray In Remote Locations and Austere Environments
Additive manufacturing (AM) represents a paradigm shift in the way that parts and products are being produced and introduced into the marketplace. It is now possible to accomplish AM not only in a manufacturing setting but in remote locations at the point of need, alleviating the logistics burden on the supply chain. Additionally, the time from conceptual design through the prototype stage and ultimately to the final test, evaluation, and qualification before production can commence is greatly reduced, resulting in substantial cost savings.
Cold Spray Technology
Cold spray (CS) is a materials consolidation process where micron-sized particles of a metal, ceramic, and/or polymer are accelerated through a spray gun fitted with a de Laval rocket nozzle to form a coating or a near-net-shaped part, by means of ballistic impingement (Refs. 1, 2). The feedstock powder particles are carried within a heated high-pressure gas (i.e., air, nitrogen, helium) such that they exit at supersonic velocities and consolidate upon impacting a suitable surface. The CS process has been developed to deposit a wide variety of engineering materials, including metals, steels (carbon and stainless), titanium, aluminum, magnesium, nickel alloys, zinc, tin, copper, tantalum, niobium, monels, brasses, and bronzes. Even gold and silver have been used in the CS process. Cermets, carbides, polymers, and/or combinations of these materials are routinely cold sprayed, including CrC-Ni, WC-Co, and many more with near theoretical density.
It is important to note that CS is considered an AM process and has been adapted to form 3D parts, as well as coatings (Refs. 3–5). Dr. Victor Champagne and his team at the U.S. Army Research Laboratory, in collaboration with the former United Technologies Research Center (now Raytheon Technology Research Center), introduced the first cold spray additive manufacturing (CSAM) part on the Patriot missile in 2018. Since then, significant advancements have been made toward the development of software specifically designed for CSAM.
SPEE3D CEO Byron Kennedy and Chief Technology Officer Steven Camilleri had worked together for more than 15 years when they founded the company in 2014. During that time, they encountered a persistent challenge: sourcing metal parts. From supply chain issues to part obsolescence, they continued to face a battery of obstacles and struggled to find an efficient way to keep equipment up and running. To simplify and accelerate the metal AM process, they began to harness the true potential of CS and created an automated CSAM process, which allows the user to avoid melting or sintering metal powders. Melting or sintering the powder can create tiny cavities in the part, reducing its density and increasing the likelihood of cracking or fatigue failure over time. The high-velocity impact created by automated CSAM produces a denser part with lower porosity, as well as enhanced mechanical properties that improve part and tool reliability over a longer lifespan.
CSAM Out at Sea
In August 2022, the U.S. Navy hosted the first-ever Repair Technology Exercise (REPTX) event to identify, validate, and implement new technologies, including AM, to help reduce supply chain issues, perform maintenance operations more efficiently, and limit travel time back to port. It was conducted as part of Advanced Naval Technology Exercise (ANTX) Coastal Trident 2022, which had more than 60 naval, academia, and industry participants. The trial consisted of a series of technical demonstrations, field experiments, and exercises, both discussion and operations-based. The WarpSPEE3D printer showcased at the event was stated to be the first to ever print parts successfully on a U.S. Naval ship — Fig. 1. The part printed was a bronze anchor that was produced five times while the vessel was engaged at sea. Parts were printed with the same results and within just six minutes each time. In addition, the SPEE3D team assisted other companies with their trials, helping print a wide range of applications, including pressure fittings for pipes, protective boxes for naval equipment, and manufacturing mechanisms for robotic arms.
“Our goal during REPTX was to successfully test WarpSPEE3D’s deployable technology to print maritime military parts on demand and in various sea conditions. We’re thrilled the results are favorable and that SPEE3D is the world’s first to print parts on a ship,” Camilleri said. “We understand the operational, economic, and supply chain issues the military faces and look forward to continuing to work with U.S. Defense to help solve some of these challenges.”
Point-of-Need Manufacturing for Cold Weather Combat Effectiveness
On December 4–8, 2023, the Office of the Secretary of Defense Manufacturing Technology (ManTech) Program featured technologies that will enable combat effectiveness in extreme temperatures. The event was supported by the U.S. Army Combat Capabilities Development Command and showed technologies recommended by the U.S. Department of Defense’s Manufacturing Innovation Institute member companies that previously competed in a Point-of-Need Manufacturing Challenge held in March 2023. Winners were chosen through an open solicitation after proposing solutions to the Department’s operational constraints in extreme cold temperatures.
According to a public report issued December 18, 2023 (Ref. 6), “SPEE3D’s 3D metal printing technology is an industry-proven, military-tested, expeditionary, all-in-one solution. The system uses existing cold spray technology to create complex 3D parts quickly. SPEE3D’s technology has been demonstrated in operations in hot and hot-humid environments, including work with the United Kingdom and Australian militaries, the U.S. Navy Repair Technology Exercise 2022, and the U.S. Army’s Project Convergence 2022. The project goal is to successfully 3D-print metal parts in a sub-freezing environment that is equivalent in quality to the same parts printed, on the same technology, in a lab environment.”
Operating In the Remote Australian Bushland
The Australian Army is rapidly developing its metal manufacturing capability with metal 3D printing technology. The Australian Army made a $24-million investment in a pilot of SPEE3D technology that was conducted in February 2020 with a 12-month trial of the WarpSPEE3D tactical printer. The trial was designed to test the feasibility of deploying metal 3D printing as a capability both in barracks and in the field. The printer uses patented CS technology that enables fast and cost-effective metal part production. It can print large metal parts up to 89 lb (40 kg) at a record rate of 0.220 lb (100 g) per minute.
Several field trials resulted in more than 50 case studies of printable parts and demonstrated that the printer can operate in remote Australian bushland and the program was extended in 2021 to verify initial results.
SPEE3D worked closely with the Australian Army to train the first military additive manufacturing cell (AMC) technicians who specialize in the production of 3D metal printed parts, from design to printing to machining, heat treatment, and certification — Figs. 2, 3. In the remote bushland of the Bradshaw Training Area, located in the Northern Territory, the AMC technicians recently tested the WarpSPEE3D tactical printer as part of its toughest trial yet. The printer was transported more than 372 miles (600 km) from the base, over rough terrain, to operate in hot and dusty conditions for three weeks — Fig. 4.
Conclusion
The ability to maneuver over complex geometries and to produce near-net shapes is a significant advantage of CS (Ref. 7) that is just beginning to be realized by the industrial community. Cold spray is often argued as not fitting the definition of AM and, as such, is often dismissed as a true AM process. However, it has been used to produce near-net-shaped parts for a variety of applications that are far superior to conventional and/or competing AM techniques when all aspects of the process are taken into consideration, especially when operating in remote locations and in austere environments.
The choice of material, the complexity of the geometry, the availability of feedstock powder, as well as the intended application are all important factors that weigh into the decision to select the CS process to fabricate parts. While the CS process is not as precise as a powder bed laser sintering process, CS is capable of high deposition rates of metals such as aluminum or titanium and for those that are highly reactive at high temperatures, such as magnesium which cannot be produced by laser sintering (Ref. 8). The CS process can easily be manipulated robotically to accommodate highly complex geometries. Additionally, it usually has no limit on thickness or length, as long as the compressive residual stresses imparted by the process are managed.
The hardware is relatively straightforward, and CS doesn’t require extensive training to operate proficiently, the utility requirements are minimal, especially when compared to conventional casting and forging, as well as competing direct-energy deposition (DED) techniques. CS has high deposition rates as compared to other AM processes, high combinations of strength and ductility, and it is cost effective making it a great choice not only for manufacturing but also for the battlefield and operating in harsh austere environments. CS doesn’t require the melting of feedstock and the consolidation of powder into a 3D printed part is accomplished in the solid state.
References
1. Champagne, V. ed. 2007. The Cold Spray Materials Deposition Process: Fundamentals and Applications, 57. Woodhead Publishing Ltd.: Abington Hall, Abington, Cambridge, England.
2. Champagne, V. K., Ozdimir, O., and Nardi, A., eds. 2021. Practical Cold Spray 1st ed. Springer Nature: Switzerland.
3. Cadney S., Brochu, M., Richer, P., and Jodoin, B. 2008. Cold gas dynamic spraying as a method for freeforming and joining materials. Surf. Coat. Technol. 202: 2801–2806.
4. Pattison, J., Celotto, S., Morgan, R., Bray, M., and O’Neill, W. 2007. Cold gas dynamic manufacturing: A nonthermal approach to freeform fabrication. Int. J. Mach. Tools Manuf. 47(3–4): 627–634.
5. Champagne, V. Cold Spray Introduction. Cold Spray Action Team Meeting, 2012–2023, coldsprayteam.com
6. U.S. Department of Defense. Point-of-need manufacturing challenge demonstrates technologies for cold weather combat effectiveness. From defense-aerospace.com/pentagon-demos-point-of-need-manufacturing-technologies-for-cold-weather.
7. Sova, A., Grigoriev, S., Okunkova, A., and Smurov, I. 2013. Potential of cold gas dynamic spray as additive manufacturing technology. Int. J. Adv. Manuf. Technol. 69: 2269–2278.
8. Nardi, A., 2012. Cold Spray Developments at UTRC. Cold Spray Action Team Meeting, Worcester Polytechnic Institute.
STEVE CAMILLERI (steven.camilleri@spee3d.com) is cofounder and chief technology officer of SPEE3D, Darwin, NT, Australia.