3D printing or additive manufacturing is ongoing revolution in manufacturing with its potential to fabricate any complex object and is being utilized from aerospace components to human organs, textiles, metals, buildings and even food. Additive manufacturing, is defined by ASTM International as the process of joining materials together, layer by layer, based on three-dimensional model data.
3D printing can make military equipment faster accelerating product development and with less cost than other processes. It increases design possibilities, enhances the speed of innovation, and offers an alternative for creating shapes closer to what an engineer might need, with fewer constraints.
3D printing is revolutionizing defence by printing small components to full drones on naval vessels, replacement parts for fighter aircrafts to printing ammunition. Substantial improvements have been made in 3D printing with the fabrication of 3D objects from metals, ceramics, plastics, and even multi-material capabilities. NASA and the US military used 3D printed components to successfully test advanced prototype airplanes, spacecraft and even ground vehicles.
Sailors and Marines are already developing new products and complex systems like drones and even munitions, expanding the realm of possibilities made real by 3-D printing while saving time, resources, and money. John Burrow, deputy assistant secretary of the Navy for Research, Development, Test and Evaluation said, “Additive Manufacturing will fundamentally change how we think, how we do business, the cost variable, and how we make decisions,” said Dr. John Burrow. “I think you are about to see its operational and technical potential literally explode off the map.” Burrow and Navy officials envision a future with 3-D printers forward deployed with Marines and installed aboard warships as well as shore-based commands.
The Subcommittee on Emerging Threats and Capabilities was responsible for setting aside $13.2bn for 3D printing of the overall $639.1 bn proposed US defence budget of 2018. The proposed bill, presented by the Subcommittee on Emerging Threats and Capabilities, outlines the “significant possibilities that additive manufacturing, or 3D printing, will provide to the Department of Defense, both in revolutionizing the industrial supply chain, as well as in providing radically new technological capabilities.”
It adds that the military would benefit from an increased number of 3D printers at “tactical levels,” and suggests that Defense Manufacturing Innovation Institutes should be established. The technology, it says, could also have applications for producing hard-to-find or obsolete parts, as well as helping to meet other demands that OEMs are unable to.
The U.S. Navy recently unveiled the military’s first 3D-printed submarine hull. Printed on the Big Area Additive Manufacturing (BAAM) machine at Oak Ridge National Laboratory’s (ORNL) Manufacturing Demonstration Facility, the Optionally Manned Technology Demonstrator is modeled after the SEAL Delivery Vehicle (SDV). SDVs are manned submersibles that are used to take Navy SEALs and their equipment on special operations missions. The BAAM has been used for many notable 3D printing projects, including the world’s first 3D-printed car, as well as ORNL’s 3D-printed Shelby Cobra.
The NDAA also highlights certain challenges that still exist with the increased adoption of 3D printing, such as the difficulty in qualifying and certifying 3D printed parts (most critically those for “in-flight or safety-critical systems). The budget proposal notes the necessity in establishing standards, and certification processes for ensuring the quality of 3D printed parts. James “Hondo” Geurts, Assistant Secretary of the Navy, Research, Development and Acquisition, has said that the force is seeking $23 million in funding for its 2020 3D printing efforts. According to Inside Defense, Guerts told the House Armed Services Intelligence, Emerging Threats and Capabilities Subcommittee, that the funds would go toward developing appropriate certification for 3D printed parts, potentially creating a database that groups all the objects together. A lot of that is so we can network all of our 3D printed files together, create models […]” he said. “One of the challenges is how to certify a part with a 3D printed technology that’s been certified traditionally. That’s where that research is going.”
US Navy’s “Print-the-Fleet” initiative
The U.S. Naval Air System Command (NAVAIR) is ramping up production of 3D printed parts. System Command estimates that it will have approximately 1,000 3D printed parts approved for use across the fleet before the end of 2018. Currently only 135 3D printed parts are authorised for use.
3D printed parts will be used in a range of Naval applications, from modifications to helmets to critical parts for aircraft: NAVAIR categorizes parts depending on their air-worthiness. Parts not requiring airworthiness can be fabricated more quickly.
Via their ‘Print-the-Fleet’ project, the Navy is trying to educate sailors about 3D printing and further integrate its use into everyday operations. The experiment has produced several applications for tooling, molding, repairs, prosthesis, cranial implants, and custom parts both on land and at sea.
The US Navy’s Vice Admiral Philip Cullom, who is charged with the Navy’s “Print the Fleet” additive manufacturing initiative, has stressed that the Navy’s logistical supply chains are vulnerable and costly, and that additive manufacturing can offset some of that cost, particularly in austere times.
Brigadier General Greg Masiello says that the Navy’s goal is not to 3D print all flight-critical components, but those that can be improved by the process. He not that some parts are “not necessarily, economically or even technically optimized for that.”
Marine Lt. Col. Howard Marotto noted that additive manufacturing is at the core of the Pentagon’s Third Offset Strategy. “I will tell you, frankly…AM is the foundation for the Third Offset,” Marotto said. “Levering the technology as agnostic as it is…is really the key if you’re going to operate as a Marine Corps in a distributed ops environment. Everything from being able to print your own parts in stream…to printing your own UAVs for ISR, for weaponization, on site, custom made, with sensors to do that exact mission that you need at that exact moment.”
With the demand for maritime surveillance on the increase, navies use manned and unmanned submersibles to deploy sensors and to provide logistics capabilities. When no two missions are identical, there’s a need to build these vessels faster and incorporate new design features.
The hull is 30 feet long, and made of six carbon fiber composite sections. The project only took four weeks to complete, and the proof-of-concept also cut production costs by 90%. According to the Department of Energy, a traditional SEAL Delivery Vehicle costs between $600,000 and $800,000, and it takes three to five months to manufacture. So, that means that they made this sub for as low as $60,000 and it was printed in a number of days — total development time took four weeks, but it only took a few days to print the six sections.
In July 2017, the U.S. Navy teamed with the Naval Surface Warfare Center Carderock Division and the Oak Ridge National Laboratory (ORNL) to create the first prototype of a 3D-printed submarine. The prototype was set to be 9.1m long and 1.4m in diameter, which meant a regular size printer wouldn’t be up for the job. So they used big area additive manufacturing, the world’s first industrial size 3D printer developed by Cincinnati Incorporated in partnership with ORNL, which boasts a print area of just over 6m in length.
The team have now received the green light to build a second watertight version that will be tested in the manoeuvring and seakeeping wave pool at the US Naval Surface Warfare Centre in Carderock, Maryland. If all goes well, fleet-capable 3D printed submersible prototypes could follow by 2019.
In 2015, U.S. Navy sailors trialed the use of additive manufacturing (3D printing) technology to build a miniature quadcopter aboard USS Essex (LHD-2) and fly it around the hanger deck. British Royal Navy ship HMS Mersey has launched an inexpensive 3D-printed drone from its gun deck. The 1.5m wingspan, propeller-driven drone, known as “Sulsa,” was 3D-printed on shore and later assembled on the ship.
The test demonstrated how more-or-less disposable drones that could be 3D printed on board would cut costs and let a crew adapt quickly to a new mission such as after a natural disaster. The Institution of Mechanical Engineers explained that, “Within five years, ships could be equipped with multi-material 3D printers able to produce entire unmanned aerial vehicles, tailored to specific missions.”
“3D printing is ideal for limited production runs, for instance if you want five [unmanned underwater vehicles] for a particular mission. It could take just two days to manufacture a plastic hull and insert the electronics”, said Jones, a production engineer.
For deployed naval forces, the key benefits of 3D printing are a shorter supply chain with reduced spares inventories (releasing space onboard ships for more valuable stores or equipment) and improved availability, according to Paul Jones, director of U.K.-based consulting firm Arke Ltd.
3D printed micro-drones dispensed in swarms from fighter jets
The Pentagon’s Strategic Capabilities Office (SCO) conducted an experiment under which micro-drones, created with 3D printing technology, could be launched from the flare dispensers of various US fighter jets. They are parachuted down in small-sized canisters, where the micro-drone wings then catch the wind with their one-inch propellers. According to SCO director William Roper, the 3D printed micro-drone swarms have been under testing since 2014, and aside from the canister launching, can also be dispersed by ground troops as well.
Each micro-drone weighs just about a pound each. The swarms are able to come together in packs and influence situational awareness from the moment they come out of the canister. They could potentially be used to confuse opposing forces and carry out more cost-effective surveillance missions. 3D printing technology helped to ensure that the micro-drones had the appropriate strength for their miniaturized size.
In March 2016, the Navy successfully test launched three Trident II D5 Fleet Ballistic Missiles made by Bethesda, Maryland-based Lockheed Martin.
The one-inch wide aluminum alloy connector backshell component protects vital cable connectors in the missile. The backshell component was designed and fabricated entirely using 3D design and 3D printing, a process that allowed Lockheed Martin engineers to produce the part in half the time it would take traditional methods. “Designs and parts previously unachievable can now be realised. Complex designs that lighten, simplify and optimise armaments are now feasible and manufacturable,” they said.
US Navy to develop 3D printed components for missile propulsion system
The United States Navy has granted Metal Technology (MTI) a contract to develop and demonstrate advanced aerospace additive manufacturing techniques for low-cost manufacturing of refractory metal components for U.S. Navy missile propulsion systems used on the Trident D5 missile system.
Recently contract has been awarded to Oregon-based Metal Technology (MTI) to develop and demonstrate 3D printing techniques for missile propulsion components. Specifically, they will be developing and demonstrating viable 3D printing aerospace techniques for the low-cost production of refractory metal components, which will be used on the Navy’s propulsion system for the Trident D5 missile system. This is a submarine-launched ballistic missile system (SLBM) that is a key part of the US strategic nuclear triad
Through this contract (a Small Business Innovation Research or SBIR contract), MTI will now be working to reduce the costs and complexity of that method. 3D printing, they believe, is a key tool in significantly reducing that complexity and lead-time, as well as the costs involved.
Jason Stitzel, the Director of Engineering for MTI, further revealed that the propulsion systems came with very complex requirements for the 3D printed parts. “Key performance requirements for the additively manufactured refractory articles include surviving exposure to greater than 3,200 degree Fahrenheit gaseous environment for 10 minutes at 550 psi, and achieving mechanical properties that meet or exceed the properties derived from traditional processing methods,” he said
3D printed munitions
Marine Corps’ Next-Generation Logistics recently printed, and then detonated, an indirect fire munition at Naval Surface Warfare Center Indian Head, Maryland. The munition, proved more lethal than traditionally manufactured munitions. And testing showed it could be developed to further improve lethality or otherwise tailor the system to the mission.
“One of the benefits of being able to precisely control the way that a munition or warhead is ‘grown’ through [additive manufacturing] is that we think we’ll be able to tailor the blast and associated fragmentation to achieve specific effects for particular targets, heights, collateral damage, or even environmental considerations,”Capt. Chris Wood, the co-lead for 3-D printing said. “Some of this can be done currently with very expensive, hand-made munitions, but [additive manufacturing] allows us to do it better, faster and likely cheaper.”
For the Marine Corps, which has more than one aging vehicle model reaching the limits of its service life, 3-D printing can be a cost-effective way to manufacture parts no longer in production
Extension to Functional Applications
Dr. Dan Berrigan, the additive lead for functional materials at the directorate, is exploring ways to use additive manufacturing processes to embed functionality into structure, such as by adding electronic circuitry or antennas on non-traditional surfaces. “Additive processes enable us to deposit electronic devices in arbitrary shapes or in flexible, soft form factors,” said Berrigan. “We are looking at different ways to make a circuit that can enable them to bend or adhere to new surfaces or geometries, such as on a dome or patch. Essentially, we are looking at ways to add capabilities to surfaces that already exist.”
For 3-D printed electronics, a conductive material is divided up into millions of small pieces and suspended in a liquid that is then dispensed from a printer, explained Berrigan. After printing, those individual conductive pieces must maintain contact to enable electrons to move through a circuit and create power. “The demand here is for low-cost, flexible electronic devices, and these direct write, additive processes give the community design capabilities that we cannot achieve otherwise,” said Berrigan.
Challenges for 3D printing
Despite years of development and research into additive manufacturing processes, there are a number of implementation challenges that AFRL researchers need to address in order to enable greater Air Force benefit from the technology, both now and in the future. “Fundamentally, it comes down to a materials processing problem,” said Berrigan.
The lack of standardized production processes, quality assurance methods, significant material variability and reduced material performance are just some of the factors AFRL researchers need to overcome. Depending on the application, material performance can be related to the strength of a part. For example, the electronic properties of an additive manufactured circuit may be worse than those of ones traditionally manufactured.
Another issue centers on basic materials compatibility. “There are a lot of different interfaces in additive manufacturing, and ensuring that materials adhere to one another or that a part can support a certain stress or withstand a certain temperature—these are all challenges we need to address,” said Miller.
The technology also has disadvantages in some cases since some jet engine components must be capable of withstanding extremely high temperatures and physical stresses. OC-ALC top scientist and engineer Dr Kristian Olivero added: “For metals in particular, the additive manufactured properties are typically somewhat lower, so what you gain in speed and flexibility, you lose some mechanical properties.
“Additive manufacturing will not provide the correct surface finish for a Class A screw thread in a crankshaft main bearing,” said Paul Jones, director of U.K.-based consulting firm Arke Ltd.
“While 3D printing gives you net tolerance – the correct dimensions – it won’t necessarily give you the right finish, so you need a CNC [computer numerical control] machine for reductive manufacture on top of the additive manufacture”, Jones explained. However it may take some time before 3D printing can build a complete functioning weapon like a missile.
“Before a warfighter can print a missile in the field,” Chris McCarroll, Raytheon director for the Raytheon University of Massachusetts Lowell Research Institute, explained, “you need [a] quality, controlled processes to fabricate all the component materials: the metallic strong backs, and the plastic connectors, the semiconductors for processors, and the energetics and propulsion systems. The hard part is then making the connections between these components, as an example, the integrated control circuit that receives the command to light the fuse. At some relatively near-term point you may have to place chips down and interconnect them with printing. Or, in the future, maybe you’ll just print them.”
The long-term goal, according to Berrigan, is for additive manufacturing to become a well-understood tool in an engineer’s toolbox, so that unique components can be design-integrated into a system. It’s difficult to go back in a system already built, he said, but additive manufacturing provides the opportunities to build-in greater potential at the start.
“The long-term vision is to have functional and structural additive manufacturing to work more cohesively from the start. Rethinking systems-level design to incorporate functionality such as electrical wiring, sensors or antennas is a potential that additive can help us address,” he said. “When you build something by layer, why not introduce channels for sensors, cooling or other functions?”
There are also safety concerns relating to hazardous materials. One 3D process requires the presence of argon gas, which is heavier than air so in the event of a leak may collect in the bowels of a ship with potentially suffocating results. The metal powders which are used to construct finished items, layer by layer, are explosive and will also require very careful storage and handling.
“Aluminium powder is massively dangerous”, said Jones, “so you wouldn’t want to keep it near where fire is possible, or where you could have an intrusion. Keep it in the weapons magazine”. “Understanding the safety, reliability and durability of a part is critical for an aircraft. We know this for parts made through other processes, but we don’t know this yet for additive,” said Berrigan.
US Navy and Lockheed Martin Are Building AI-Driven 3D Printing Robots
A new generation of smart 3D printers is under development which will use artificial intelligence to oversee and optimize 3D printed parts. The US Navy’s Office of Naval Research (ONR), which is funding the ambitious project, has recently announced a two-year $5.8 million contract. There are four partners working on this project, led by Lockheed Martin’s Advanced Technology Centre. The collective aim is to be able to create robots that can make independent decisions on how to optimize the production of complicated 3D printed parts.
Currently, 3D printing is useful in a huge number of industries, but still requires high levels of “babysitting” and constant monitoring to ensure success. This is the reason why the US Navy is researching how artificial intelligence can be applied to train robots to reduce this workload while still creating complex, high-quality parts.
The researchers are developing new software models and sensor modifications to result in better 3D printed parts. But, central to this contract is “verified analysis and integration into a 3D printing robotic system”. In other words, the 3D printers will be capable of making proper adjustments on their own by using machine learning algorithms. The 3D printing robots will learn from each other and train themselves, continuously optimizing the process.
Brian Griffith, Lockheed Martin’s project manager, said: “We will research ways machines can observe, learn and make decisions by themselves to make better parts that are more consistent, which is crucial as 3D printed parts become more and more common… Machines should monitor and make adjustments on their own during printing to ensure that they create the right material properties during production.”
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