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.
“Additive manufacturing technology has the ability to improve the performance of Army weapon systems on the battlefield. Additionally, 3D printing gives the Army a tactical advantage by providing the ability to manufacture and produce items as close to the point of need as possible. This will not only lighten the logistics burden but also improve the efficiency of the acquisition process. By simplifying the process of repairing or producing spare parts, the Army will make critical gains in readiness,” states the Army.
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 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.
Army 3D printing
Army researchers are exploring many frontiers of this exciting technology, “Imagine the possibilities of three-dimensional printed textiles, metals, integrated electronics, biogenetic materials and even food,” said Dale Ormond, Director of Research and Development.” “The vision is to be able to have additive manufacturing as a tool in the toolbox so that Soldiers can manufacture and produce a product as close to the point of need as possible,” said Andy Davis, program manager for the Army’s Manufacturing Technology program (ManTech).
A three-year Army program called “Automated Construction of Expeditionary Structures,” or ACES, has been exploring the use of 3D printing to build semi-permanent structures from concrete made with locally available materials. In August, ACES was used to 3D print an Army barracks. Another first for ACES – this is the first time it’s 3D printed a structure on an uneven gravel surface; big news, as most 3D printers need flat surfaces to work properly.
Kreiger said that the system has been working well under multiple weather conditions, and only took 21.5 hours to 3D print a barracks hut that could house 20 soldiers. Even more impressive is the fact that ACES built a smaller, simple bunker structure in only two hours.
In terms of defense applications, 3D printing has shown particular potential as a means of creating spare parts on-demand, something that could be advantageous to isolated soldiers on the battlefield. As a result, the DoD has commissioned ExOne to develop a ‘portable 3D printing factory,’ that’s capable of producing spares anywhere in the world.
Similarly, the U.S. Army has previously acquired a Rize One 3D printer for on-demand production purposes, and adopted MELD Manufacturing technology to repair military vehicles on the move. However, questions over reliability continue to prevent the further roll-out of additive parts within the military, as they often need to be demonstrably bulletproof to make them useful in end-use scenarios.
In an attempt to address this, the U.S. Army’s Research Lab (ARL) has chosen to adopt machine learning (ML), as a means of better understanding part wear. For instance, the ARL recently deployed Senvol’s ML software to assess the efficacy of 3D printed missile parts, and using similar simulations, engineers at Penn State are now seeking to qualify their alloy-based approach, albeit for larger-format applications.
Food researchers in the US Army are looking into ways to 3D print food for soldiers that could produce meals on demand for soldiers in the battlefield. By combining wearable technology capable of measuring a soldier’s individual physiology with food 3D printers, future Meal Ready-to-Eat (MREs) will be automatically generated meals that have been tailored for the specific nutritional needs of each soldier. Because the Army’s Meal Ready-to-Eat (MRE) standard for food has a shelf life of three years, 3D printing creates new options that could make meals have longer and more stable shelf lives according to Lauren Oleksyk, Natick Soldier Research, Development and Engineering Center (NSRDEC).
Dr Thomas Russel, Director of the Army Research Lab said: “For soldiers, there are some medical benefits. Many of the injuries soldiers receive in the field are not traditional. A lot of the medical community sees this as a new approach to medicine. We can 3D scan injuries.”
According to Mike McCarthy, deputy to the commanding general for the Maneuver Support Center of Excellence at Ft. Leonard Wood, this strategy has helped the US military become more efficient while also modernizing operations. McCarthy explained, “Using this process takes 40 percent less time from concept to fielding new technology than traditional methods. It also has a significant cost savings. You don’t have to go back and fix it after fielding.”
Improved communication bandwidth meant patterns to build components layer-by-layer could be transmitted almost instantly to remote locations that hadn’t previously known they needed a part until something went wrong. US Army’s Rapid Equipping Force Fablabs project in Afghanistan deployed a mobile fablab in theater. This fablab has 3D printers, laser cutters, milling machines and other equipment. The idea was to quickly assist troops with 3D printing items that they needed.
However, as the technology edges towards print-on-demand capability, future commanders could assess a combat operation and build the vehicles, surveillance tools, weapons and ammo they need from scratch, eliminating a long wait for a logistics delivery across hazardous terrain.
Additive manufacturing technology roadmap
The Army recently completed an additive manufacturing technology roadmap, which was sponsored and managed by ManTech. According to the Army, this was combined with the Department of Defense (DOD) Roadmap, outlining goals for all branches of the military. “The DOD roadmap also identifies current and future capabilities that are needed to enable AM and areas for collaboration,” states the Army. “These common standards set out in the roadmap will enable the DOD, industry, and academia to effectively use AM.”
Their 3D printing plan has been implemented in three steps, beginning with 3D printing to make or replace existing parts. This has already been helpful for many parts of the military—even if they are just 3D printing temporary parts until the others can be received. 3D printing is also helpful in prototyping new parts. In the second part of their plan, they are eliminating multi-part assembly. The Army also plans to begin creating new parts that did not exist previously.
The roadmap covers four key areas critical to using additive manufacturing efficiently and effectively:
— Materials: what must be done to develop, mature and capture associated data for materials.
— Design: how to develop and use advancements in the computer-aided design and engineering fields for additive manufacturing products, as well as how to best use the capabilities.
— Process: what additive manufacturing processes can be used to make AM parts, and what process capabilities are needed.
— Value Chain: the most efficient and cost-effective way to use AM and the infrastructure required to support it.
“The Army relies on the manufacturing prowess of industry to keep our Soldiers the best-equipped in the world because having the best equipment, the right equipment in the right quantity when you need it is an essential component of making our Soldiers the safest and most effective in the world,” said Maj. Gen. Cedric T. Wins, commanding general, U.S. Army Research, Development and Engineering Command (RDECOM)
3D printing munitions
Researchers at the U.S. Army Armament Research, Development and Engineering Center (ARDEC) successfully fired the first grenade created with a 3-D printer from a grenade launcher that was produced the same way. is a tangible testament to the utility and maturation of additive manufacturing. It epitomizes a new era of rapidly developed, testable prototypes that will accelerate the rate at which researchers’ advancements are incorporated into fieldable weapons that further enable our warfighters.
RAMBO and the test rounds were fired for the first time last October at a facility in New Jersey. According to the researchers, 15 test shots were fired, with muzzle velocities matching conventional grenade launchers to within five per cent. Furthermore, the weapon showed no signs of degradation after firing.
RAMBO is based on the 40mm M203A1 grenade launcher, which contains 50 components. All of these, with the exception of springs and fasteners, were produced using various additive manufacturing techniques. The barrel and receiver were fabricated from powdered aluminium using direct metal laser sintering (DMLS) in a process that took about 70 hours. Other components, including the trigger and firing pin, were printed using 4340 alloy steel, which is the same material used to make the weapon by traditional methods.
And then there’s the warheads; “3D printing of warheads will allow us to have better design control and utilise geometries and patterns that previously could not be produced or manufactured,” Zunino said , a materials engineer for the Army. Considerable investments are being made worldwide to develop, qualify and certify 3D printed parts for the military.
Ex Labs Mobile
RDECOM partners with the Army’s Rapid Equipping Force to manage, staff and support expeditionary labs, or “ex labs,” which can be deployed worldwide. Ex labs are designed to supply innovative equipment to forward-deployed Soldiers as quickly as possible. One lab is currently located at Bagram Airfield in Afghanistan and another at Camp Arifjan, Kuwait.
Each ex lab is built into a 20-foot shipping container and two ISU 90 shipping containers, which hold a 3-D printer as well as supporting equipment and the computer-aided design workstation used to create the virtual working models that are then constructed by the 3-D printer. The labs are also stocked with traditional tools, equipment and software to design and fabricate metal and plastic parts
The on-site ex lab team includes a Rapid Equipping Force noncommissioned officer in charge, a RDECOM lead engineer, a support engineer, and a machinist. Together, they develop solutions using textiles, electronics, subtractive manufacturing and additive manufacturing.
“The labs have an open-door policy so the Soldier can come in and describe his mission capability shortfalls, and the [ex lab] team immediately starts brainstorming ideas and solutions,” said Angel Cruz, RDECOM ex lab project lead. RDECOM plans to develop additive manufacturing in three phases. Phase one will use additive manufacturing to repair and replace existing parts. Phase two will reduce multipart assemblies from a series of parts to one part.Phase three will use additive manufacturing to create new parts that don’t already exist.
Army’s “On-Demand Small Unmanned Aircraft Systems”
In December 2016, engineers from the Army Research Laboratory flight tested 3-D-printed unmanned aircraft created with a new on-demand system. Army’s “On-Demand Small Unmanned Aircraft Systems” developing new technology that will allow Soldiers to request small unmanned aircraft system on the spot with the use of 3D printing. “We’ve created a process for converting Soldier mission needs into a 3-D printed on-demand small unmanned aircraft system, or ODSUAS, as we’ve been calling it,” explained Eric Spero, team leader and project manager. Based on the feedback engineers received from Army leaders, Eric Spero said, his team plans to work on improving noise reduction, standoff distance, and agility, as well as increasing the 3-D-printed drone’s payload capacity.
“A reconnaissance patrol requires UAV support and sends mission requirements to the fabrication lab. ARL software configures a UAV based on the Soldiers request and designs the vehicle with off-the-shelf and 3D printed parts. The pieces are then assembled and the UAV is sent to out into the field within 24 hours of the initial request.”
“The technology provides an unmanned teammate in support of manned/unmanned teaming,” Eric Spero, an acting team lead in the ARL Vehicle Technology Directorate wrote. “Small UASs equipped with sensors, for example, day or night, still or video, can provide preemptive threat detection and identification.” If small UASs are built on-demand, they can be customized to autonomously deliver specific supply classes via air.
“Small UASs can also be used to investigate weapons of mass destruction at a safe stand-off distance, looking beyond gaps, collecting forensic data, and breaching complex obstacles such as those that require hover-flight capability,” Spero wrote.”The solution is envisioned to be available at the battalion level and below, supporting the company, platoon, squad and individual Soldier,” Spero said.
“We saw the trajectories of two beneficial technologies converging, 3D printing and small unmanned air vehicles, to support small unit decentralized decision making in complex environments,” said Eric Spero, an acting team lead in ARL Vehicle technology directorate.
3D Systems has announced its partnership with U.S Army Research Laboratory (ARL), America’s premier research center for land forces. This partnership is to jointly develop 3D printing technology and materials for automotive, medical, wearable, aerospace and other commercial and defense applications at the Army’s Aberdeen Proving Ground at Maryland.
“Additive manufacturing is redefining what is possible. Novel materials research will enable areas like 3D printed electronics and multi-functional structures. The development of hybridized manufacturing technologies will allow in-field manufacturing, efficient depot-level repair and a reduction of the Army’s overall logistics burden,” said Larry (LJ) Holmes, the Army Research Laboratory’s Principal Investigator in this effort. ”
Researchers 3-D print ultra-strong steel parts from powder
The US Combat Capabilities Development Command (CCDC) of the Army Research Lab (ARL) have recently utilized a customized steel alloy powder to produce high-strength metal 3D parts, which serve as spares for ground vehicles. AF96 is a low alloy, high-strength performance steel developed by the Air Force. It exhibits high impact toughness and shock survival, and is resistant to bending and abrasive material losses such as high-performance penetrating weapons. For this reason, the material is known as bunker buster.
AF96 powder is used in Laser Powder Bed Fusion (LPBF), which employs a laser to melt and fuse the 3D printed materials. With this method, a 3-D printer’s laser selectively melts the powder into a pattern. The printer then coats the build plate with additional layers of powder until the part is complete. The end result is a piece of steel that feels like it was forged traditionally, but has intricate design features that no mold could create, and is about 50% stronger than anything commercially available. The result is vehicular components, which are reportedly 50% stronger than commercial equivalents. This can have massive effects on the sustainability and effectiveness of army logistics chains.
“We’re able to print up parts with internal structures that they would not necessarily be able to create with that much dimensional accuracy where they try to use mill or machine part,” said Dr. Andelle Kudzal, a materials engineer on McWilliam’s team.
“This material that we’ve just printed and developed processing perimeters for is probably about 50 percent stronger than anything commercially available,” McWilliams said. The Air Force initially developed this alloy for bunker-busting bomb applications. They needed a metal that was very high-strength and high-hardness, but they also needed it to be economical.
“I think it’s going to really revolutionize logistics,” said Dr. Brandon McWilliams, an Army team lead. “Additive manufacturing is going to have a huge impact on sustainment…instead of worrying about carrying a whole truckload, or convoys loads of spares, as long as you have raw materials and a printer, you can potentially make anything you need.” Researchers say this capability has the potential to replace parts of today’s tanks, or support future, state-of-the-art systems.
AF96 has exhibited proof-of-concept when utilized to print impeller fans used to cool the fan motor in the engine of an M1 Abrams tank, a third-generation American battle tank designed by Chrysler Defense (now General Dynamic Land Systems). The fan allows the air to flow evenly and control the temperature of the vehicle. For Army applications, the key to usage is certification. Will the part work as needed in a battlefield scenario?
In terms of a battlefield scenario that may be good enough to be able to get your tank running again for hours or days if that’s important to the mission, but on the other hand, we still need to be able to answer, does this perform as good as the OEM [original equipment manufacturer] part? Does this perform better?” The researchers said it comes down to two real strategies. One is for battlefield sustainment, the logistics piece — the replacement of existing parts and supporting legacy systems, but the second strategy is about futures systems.
By 3D printing metal parts remotely, the CCDC aims to reduce the strain on the army logistics chain. Instead of requesting a replacement part from thousands of miles away, troops could print it and recommission a vehicle much faster and at a fraction of the cost. Rather than carrying truckloads of spare parts, including convoy loads, all a unit would need is a 3D printer and raw materials.
3D printing can also help increase the operational lifetime of legacy equipment by shortening the supply chain back to the manufacturer, which may not have spare parts anymore. These parts may weigh less thanks to composite materials and decrease the weight of weapon systems, meaning the unit as a whole is lighter and can move faster.
The US Army is following in the footsteps of the French Army, which already uses Formlabs and Ultimaker 3D printers to produce spare parts such as protective shells, seals and optics parts. In doing so, they are accelerating the supply chain and reducing transportation costs.
The CCDC and academic researchers are working on nickel-titanium alloys that model AF96 and other alloys to produce high-performance materials that will be stronger and more heat-resistant. The ARL had funded two 3D metal printing projects at the University of Texas at El Paso (UTEP). The first will use infrared cameras to develop an intelligent system to monitor and auto-correct powder bed fusion based processes to avoid defects and make real-time corrections.
The second seeks to enhance the mechanical properties of metal parts through nitride coatings; the nitriding process would occur during the print job to tailor the microstructure of the part for optimum use. There are many benefits to utilizing 3D printing to produce metal parts to be used in the army’s ground vehicles. The ability to print on-demand means fewer spare parts need to be transported, lessening the load on logistics chains, reducing costs and allowing units to move more quickly.
Australian Army trials SPEE3D’s WarpSPEE3D metal AM machine in the field in 2020
SPEE3D, headquartered in Melbourne, Australia, reports that its WarpSPEE3D metal Additive Manufacturing machine was deployed by the Australian Army and trialled during a field exercise in the Northern Territory. The trial was used to demonstrate the potential for the company’s metal AM technology when deployed in a military scenario.
WarpSPEE3D offers large-format metal Additive Manufacturing, using the company’s patented cold spray technology. According to SPEE3D, this enables significantly faster and more cost-effective metal part production than traditional manufacturing. It is capable of building metal parts up to 40 kg at a speed of 100 grams per minute.
During the three-day trial, the WarpSPEE3D was manoeuvred to various locations and unloaded on different terrains. The AM machine was unloaded and operational within thirty minutes, producing a variety of additively manufactured parts.
The Australian Army announced a $1.5 million investment in a pilot of SPEE3D technology in February 2020, with a twelve-month trial designed to test the feasibility of deploying metal AM machines both on-base and in the field. SPEE3D states that it partnered with the Advanced Manufacturing Alliance (AMA) and Charles Darwin University (CDU) to deliver the programme with soldiers from the Australian Army 1st Brigade training in Additive Manufacturing at CDU since February. The programme aims to significantly increase the availability of unique parts to the army compared to what the regular supply chain can provide.
“The first field deployment of WarpSPEE3D was an important milestone for SPEE3D,” stated Byron Kennedy, SPEE3D CEO. “While our equipment was initially designed for industrial use, this trial proved that our equipment is actually very robust and can endure harsh conditions and rough handling very well. We look forward to future exercises and continuing to learn how we best serve the Australian Army and defence industry.”
Military-spec filament produces stronger 3D-printed objects
Compact, inexpensive 3D printers typically utilize a process known as fused filament fabrication (FFF). This involves heating a plastic filament to its melting point, then extruding it through a nozzle. Successive layers of the molten plastic are deposited one on top of the other, forming a single solid object as they cool and fuse together. According to US Army engineers, though, items printed in this fashion tend to be too structurally weak for rough-and-tough use by soldiers in the field. And although there are printers that use non-FFF techniques to produce stronger objects, those machines are large and costly, making them impractical for field use.
Dr. Eric D. Wetzel of the Army’s Emerging Composites team led the project to create a stronger filament. They ultimately created a new dual-polymer filament that allows consumer 3D printers to produce much stronger items, utilizing their existing FFF hardware. The team fabricate a billet of material comprising ABS, with a star‐shaped PC (polycarbonate) core. That column is then put into a machine called a thermal draw tower that heats one end and draws it out into a thin filament that’s cooled and spooled for later use on any FDM 3D printer. The new filament consists of ABS and PC so the DM (dual-material) parts are annealed after printing to completely fuse the two materials, maximizing the strength and heat deflection temperature.
Tests revealed that the DM parts have ductility that’s similar to injection molded ABS parts and have fracture toughness values 15 times higher than comparable printed ABS parts. And there’s little shrinkage or warping that occurs during the annealing process because the “PC skeleton of specimens fabricated using the DM filament resists creep and polymer relaxation to maintain accurate part geometry during annealing.”
The engineers tried eight different shapes for the PC core, including a circle and different numbers of spokes but the asterisk shape exhibited the best mechanical properties. With more research from 3D printing and materials companies that the Army is requesting, this could lead to significantly stronger parts for everyone with an FDM printer. In the paper published in the journal Advanced Engineering Materials, the authors use no uncertain terms, “This novel DM filament can revolutionize additive manufacturing allowing low‐cost printers to produce parts with mechanical properties competitive with injection‐molded plastics.”
Researchers based at Penn State’s College of Engineering have been awarded $434,000 by the U.S. Army to develop an optimized method of 3D printing high-strength alloys.
During the project, the team intends to use computer modelling to identify a Laser Directed Energy Deposition (L-DED)-based setup, that’s capable of printing more robust metals with enhanced material efficiency. Such high-grade steels could have multiple defense-related applications, ranging from bulletproof vests to blast-proof protection for the hulls of naval ships.
“These materials are a completely new class for additive manufacturing,” said Amrita Basak, Co-principal Investigator on the project. “What we find can help the research community pursue this further, and perhaps the Army will discover new ways to use these materials to further their mission.”
While it’s clear that robust 3D printed metal parts have significant potential when it comes to military shielding, some performance alloys can be difficult to process. In particular, high-grade steels are more prone to cracking, and exhibit low weldability compared to conventional materials, limiting their defense-related applications.
To get around this, Basak now intends to work with the project’s Principal Investigator Todd Palmer, to develop an optimized wire-fed manufacturing process. As opposed to powder-fed machines, the engineers anticipate that adopting a wire-based approach could enable them to make the process more cost-efficient, while wasting less material as well.
According to Palmer, Penn State is uniquely well-positioned to conduct the research: “Our vertical integration around AM is a real strength at Penn State,” said Palmer. “We have experts on the experimental side, and also on materials, numerical methods and machine learning. That’s what sets us apart: we can bring these people across disciplines together.”
During the project itself, the team is set to use computer modeling to test and refine the parameters of their process, before simulating end-part performance. Once perfected, the engineers then aim to assess their approach practically, using Penn State’s machines to create large-format test parts, and generate experimental data that could prove useful in future end-use military scenarios.
For Basak, having access to Penn State’s extensive 3D printing resources, will prove vital to testing the efficacy of their approach. “In this project, we are exploring very large structures,” concluded Basak. “If we didn’t have 3D printers large enough to create these, we couldn’t do much. But we have many, and we will need them all to successfully complete this project.”
Recent innovations in L-DED
Wire-fed DED is quickly emerging as a faster and cheaper alternative to similar powder-based technologies, and Sciaky has established itself as one of the market leaders in this area, with its high-deposition rate EBAM 3D printers.
The company has often been contracted to 3D print defense-related parts under NDAs, but in 2017, it opted to publicise a project that saw it fabricate a metal AUV submarine component. Elsewhere, EBAM has also been used to create the internal structure of airplane wings, reflecting the broad potential of wire-fed technologies.
In a similar vein, Reliance Precision and the University of Huddersfield are working on a potential alternative to EBAM as part of an Innovate UK-backed program. The joint team of engineers are essentially attempting to develop an optimized EB-based process that drives the technology’s wider industry adoption.
Likewise, Hybrid Manufacturing Technologies (HMT) is also leading an Innovate UK project, which is focused on fast-tracking the R&D of a new compact wire-feed system. Once the new DED design is ready, HMT intends to work with TWI and Epoch Wires, to optimize its performance and accelerate its market uptake.
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