During a port call nearly a decade ago, my ship’s flight-deck net frame and bracket were damaged, compromising the net’s structural integrity, decertifying our flight deck, and preventing us from launching our embarked helicopter. Several members of the engineering department worked through the day welding the bracket and straightening the frame. As the operations officer, I coordinated with various operational and administrative commands and obtained a waiver for the net after conducting a weight test. After the port call, we sailed about 800 nautical miles (nm) in nearly three days to Naval Station Guantanamo Bay, Cuba, where we spent another day installing and weight testing a new net before recertifying the flight deck and resuming patrol, steaming another 800 nm and three days to our operating area.
This casualty cost the ship a week of operational time out of a roughly nine-week patrol. The incident occurred when additive manufacturing (AM) remained in the “emerging technology” realm. If a ship experienced a similar casualty today, given the wide availability of AM technologies, would it be cheaper and more expedient to use AM to “3D print” the broken bracket? And if so, how could the Navy and Coast Guard effectively deploy this technology to maximum benefit?
47-foot motor lifeboat. U.S. Coast Guard (Veronica Bandrowsky)
Deploy the Supply Chain
Every ship and deployed force experiences equipment casualties that affect mission performance, requiring either immediate repairs, a reduction in operational capabilities, or both. The current answer to this dilemma is to use just-in-time or, more frequently, demand-driven supply chains, shipping critical components into the operational theater to meet the ship at its next port call. Popularized during the 1980s and 1990s, these supply chain practices reduce the need for large inventories of parts afloat, freeing valuable shipboard storage space.1
These practices continued until the 2020 COVID-19 pandemic strained supply chains and forced businesses to reevaluate whether they could survive with just-in-time or demand-driven logistical tails.2 But while the private sector took stock, the Sea Services continued using demand-driven practices for an obvious reason: In fiscally challenging times, demand-driven supply chains reduce inventories, which reduces the costs associated with maintaining such inventories. However, they also reduce crews’ ability to quickly correct equipment casualties beyond those requiring basic maintenance, as they no longer have the parts on board. For this reason, the services increase mission-execution risks to drive down costs.
While this model enabled the services to adapt to a post-recession, post-sequestration environment in the early 2010s, advances in AM now require senior military leaders to reevaluate demand-driven supply chain practices as the private sector has already done. However, unlike the logistical challenges of previous decades, the question is no longer whether to carry large inventories of parts, but rather whether to place the manufacturing and maintenance schedules back in the hands of ships’ crews. By investing in AM equipment, training, and materials, logistics managers and forward-deployed crews could expedite casualty repairs with minimal loss of operational capabilities and time.3
The Additive Manufacturing Hype
Various articles over the past decade have trumpeted the value of AM.4 Some argued that AM could reduce the need for resupply ships and aircraft by enabling production of parts.5 Others suggested it might be possible to “print” an entire ship at some point in the future.6 And most authors argued that AM will be a force multiplier and revolutionize military supply chains by providing the “capability to manufacture any part, anywhere.”7
While AM technology holds promise for augmenting the military supply chain, significant challenges must be overcome to move the technology out of labs and into one of the environments most hostile to technology on the planet—the sea. Ships at sea experience constant dynamic forces through roll and pitch. When ships pitch and roll, they experience forces similar to gravitational forces as they contend with the immense energy of the ocean. In addition to these forces, the sea itself is highly corrosive to metals, and the combination of a large body of water and atmospheric dynamics can cause humidity levels to vary greatly in the span of a few hours. Researchers across the federal government conducted experiments on the viability of AM in recent years, with results indicating additional engineering work could potentially overcome many of these environmental challenges, but more data is required on the effectiveness of AM parts production at sea.
Other challenges include determining how to deploy AM equipment on existing ships given the limited space and the likely need to retrofit ship spaces to accommodate AM operations and store feedstock. Furthermore, procuring the requisite equipment and various feedstocks could present an obstacle, particularly given the cost of some of these materials. Finally, training, maintenance, and personnel costs associated with AM could make deploying AM equipment larger than tabletop models cost prohibitive. These shipboard challenges could quickly undermine the technology’s potential if not addressed upfront with detailed planning.
Limited Shipboard Space
AM equipment and feedstock take up valuable shipboard storage space. While many advocates argue that AM technology is necessary because it is infeasible for ships to carry all the possible parts that might be required to conduct repairs, they often fail to address the need to store the equipment and large quantities of feedstock on board the ship. In addition, for AM to truly provide on-demand repair capability, ships will have to carry one or more additional AM machines in the event the main machine fails. All this equipment and feedstock requires storage space and, depending on the type of feedstock material and its sensitivity, such storage will need some form of climate control to maintain steady temperature and humidity levels. Failure to control for these variables could result in feedstock compromises that degrade the manufactured equipment.8
Currently, the storage space issue remains a distant thought as military and civilian entities test the viability of shipboard AM processes in a range of environments.9 Most of these experiments use one or two machines, ranging in size from a countertop microwave to a medium-sized household generator, and only enough feedstock for experimentation.10 However, as the Sea Services increase the deployment of AM equipment on board ships, they will also need to expand the types and quantities of feedstock required to manufacture a greater variety of replacement parts, from plastic valve handles to metal small-boat propellers and lifeline stanchions. As a result, commanding officers, naval engineers, and logisticians should anticipate dedicating increasing amounts of shipboard space to AM equipment and feedstock.
Additive Manufacturing Supply Chain Issues
The challenges of integrating AM into shipboard operations and logistics go well beyond having enough storage space. Entire AM supply chains will need to be established to ensure the necessary resources, training, equipment, and support are in place. While the services can handle these issues relatively easily now as they
prototype technologies, AM logistics will become significantly more complicated when hundreds or thousands of 3D printers of various makes and models are on dozens of classes of ships.
When contemplating deploying shipboard AM equipment at scale, the services will have to determine who will operate and maintain such systems. One can envision the ship’s AM shop operating continually for weeks to months while ships are deployed and only shutting down for the occasional port call or for periodic maintenance. This would require a dedicated division of at least eight technicians. Consequently, the services will need to make a variety of personnel decisions, such as whether to establish an AM rating and what other departments should be reduced to avoid increasing overall crew size. While it is not uncommon for the services to establish new ratings, establishing an AM rating will take years and lag AM equipment installation, leaving commanding officers to determine how best to incorporate AM capability and leading to significant variance across the fleet.
The services also will need to establish formal training pipelines for those who operate and maintain AM systems. Currently, only the various producers of AM machines provide training on the use and maintenance of their equipment. The services will need to decide whether to continue using industry-provided training—either from the equipment producers or through a contracted third-party vendor—or establish AM operations and maintenance schools. For the latter, the services will have to limit the number of AM models deployed in the fleet to allow schoolhouses to develop and implement a thorough curriculum.
Beyond personnel, the services will need to determine the maintenance process for AM machines. The number of machines per ship, the operating parameters including length of continuous operations, and whether ships’ crews should conduct preventative maintenance on the systems will all need to be determined before full deployment. Perhaps the most interesting question for the services is whether ships should maintain spare AM machine parts on board, or produce their own replacement parts using redundant machines. This determination will rely on a variety of factors, such as selected model, ease of maintenance, availability of parts, and whether the specifications and tolerances for replacement parts can be achieved through shipboard AM processes.
Finally, the most significant challenge to adopting this technology at scale will be the costs and budgetary constraints. AM machines can range from $100,000 for small commercial units to almost $2 million for units that can produce large parts equivalent to car engine blocks.11 Assuming an average unit cost of $1 million, the Navy would spend more than $600 million to provide each ship with two units for redundancy. For the Coast Guard, it would cost almost $150 million to provide its fleet two-unit redundancy.
Both services would also need to determine annual costs for maintenance, spare parts, and repairs, as well requisite shipboard outfitting of feedstock materials, which can range in price from $30 to $700 per kilogram of material.12 While feedstock usage rates vary depending on the item being produced, research indicates that mass production of parts through AM may not be more cost effective than traditional manufacturing processes.13 Coupled with the indirect costs of personnel and training, mass investment in shipboard AM for maintenance and repair may prove more costly than the traditional logistics processes currently employed.
Additive Manufacturing Support Ships
Shipboard AM does have the potential advantage of providing immediate replacement parts during deployments, reducing maintenance downtime and enabling consistent combat readiness. How best to provide this capability will require the services to weigh the costs and benefits of various shipboard AM deployment models. Providing each ship this capability may be ideal for small-scale, small-sized production capabilities, but large-scale or large-sized production will require other options.
One such option would be to field AM support ships, akin to Military Sealift Command’s fast combat support ships (T-AOEs) for carrier strike groups (CSGs). Consolidating higher-end AM capabilities on board a purpose-built vessel could alleviate some key challenges to fleetwide AM deployment. Designed for AM capabilities, these ships would have dedicated storage for the feedstock necessary to manufacture a wide range of products, while also being able to resupply other ships with requisite feedstock. The design would also provide sufficient space for large gimbal-stabilized machines capable of producing larger components than current shipboard capabilities presently can achieve, and those spaces would be in optimal locations at the center of the ship to mitigate the effects of roll and pitch. The size of AM ships, likely equivalent to the Supply-class T-AOEs, would reduce the motion induced by seas and swells compared with what destroyers and Coast Guard cutters experience.
This would allow the services to consolidate personnel and training costs by limiting the number of operators and maintainers to dozens stationed on several AM support ships. AM support ships would embark expert operators and maintainers whose only responsibilities would be to manufacture large-scale or large-sized products for transfer to other ships. In this capacity, the AM support ships’ crews would augment the small-scale, small-size manufacturing that could be accomplished organically on combatant ships.
For AM support ships to become a viable option, the costs of AM would need to decrease to be comparable to those of traditional manufacturing. With AM costs ranging 50 to 180 percent higher than traditional manufacturing, it would be a hard sell to get policymakers to invest in a fleet of AM ships at more than $700 million per ship, based on cost estimates for comparable ships.14 Including the operating, maintenance, and personnel costs would make an AM fleet even more expensive. However, the estimated costs of retrofitting this capability into existing ships are not readily available to provide a thorough cost-benefit analysis of alternatives.
As promising as AM support ships may be, they would provide value to other ships only when part of a CSG. Ships operating independently would not be able to rely on AM support ships to manufacture products, and instead would have to rely on either traditional supply chains for parts and repairs or the organic capability to produce large-size products as needed. Independently deployed surface combatants, submarines, and Coast Guard cutters would not be able to field a full array of AM equipment, and would be required to balance size, cost, and capability to manufacture products.
Whither afloat Additive Manufacturing?
While using AM technology to replace a broken flight-deck net frame and bracket would likely be less expensive and more expedient than a six-day, 1,600 nm detour to pick up the part, the services have not evaluated the cost effectiveness of AM at scale. Shipboard AM will not eliminate the need for traditional supply chains, and significant challenges remain for widescale implementation, but the promise of rapidly making replacement parts while deployed requires the Sea Services to explore AM deployment models, including dedicated support ships. Regardless of model, however, a trained workforce of AM operators and maintainers will be needed to provide critical operational support when equipment and systems fail.
1. Georgia Wilson, “Timeline: The History of Just-In-Time Manufacturing,” Manufacturing, 1 December 2021.
2. Peter S. Goodman and Niraj Chokshi, “How the World Ran Out of Everything,” New York Times, 1 June 2021.
3. Stew Magnuson, “Navy Must Go All in on Additive Manufacturing, Official Says,” National Defense, 17 March 2023.
4. Andrew Shaughnessy, “Army of Makers: Harnessing the Power of America’s Hackers and Innovators,” Modern War Institute, 7 November 2018; and Diego Laje, “Hot Off the 3D Presses, Navy Develops Additive Manufacturing,” Signal, 1 February 2023.
5. LT Andrew Kramer, USN, “Print a New Navy Supply System,” U.S. Naval Institute Proceedings 144, no. 5 (May 2018).
6. LT Scott Cheney-Peters, USNR, and LTJG Matthew Hipple, USN, “Print Me a Cruiser!” U.S. Naval Institute Proceedings 139, no. 4 (April 2013).
7. CPO Michael Larson, USN, “Manufacture Critical Parts on Site,” U.S. Naval Institute Proceedings 149, no. 2 (February 2023).
8. Lonnie J. Love et al., Evaluation of Ship Board Additive Manufacturing: Final Report (Oak Ridge, TN: Oak Ridge National Laboratory, April 2014).
9. Naval Sea Systems Command, “New Additive Manufacturing Printer Enables Sailors to ‘Think Outside the Box,’” Office of Corporate Communication, 24 February 2023; Edward Lundquist, “3D Printing: Navy Builds Up Additive Manufacturing on Ships,” MarineLink, 26 January 2023; and Brennan T. Phillips et al., “Additive Manufacturing Aboard a Moving Vessel at Sea Using Passively Stabilized Stereolithography (SLA) 3D Printing,” Additive Manufacturing 31 (January 2020).
10. Phillips et al., “Additive Manufacturing Aboard a Moving Vessel at Sea.”
11. Terry Wohlers and Olaf Diegel, “Costs and Considerations When Investing in a Metal Additive Manufacturing System,” Metal AM 3, no. 4 (Winter 2017).
12. Timothy W. Simpson, “Plotting a Pathway to Profitable AM,” Additive Manufacturing, 11 May 2012; and Anna Mohit, “Efficient Additive Manufacturing Pricing,” Layers blog, 15 August 2021.
13. Sangjin Jung et al., “Is Additive Manufacturing an Environmentally and Economically Preferred Alternative for Mass Production?” Environmental Science & Technology 57, no. 16 (25 April 2023): 6376–86.
14. Rich Smith, “Should the U.S. Navy Spend $10 Billion to Build a Fleet of Floating Gas Stations?” The Motley Fool, 1 September 2014.
