ADDITIVE MANUFACTURING AND ITS MILITARY APPLICATIONS

Col Harpreet Singh*

About Additive Manufacturing

Conventional tool room methods for production generally consist of subtractive manufacturing methods such as CNC milling, turning, and precision grinding. In case of Additive Manufacturing (AM) material is added by 'printing' and the process is also known as 3D Printing, though printing is just a part of the AM process. Early additive manufacturing equipment and materials were developed in the 1980s. In 1984, Chuck Hull of 3D Systems Corporation filed his own patent for a stereolithography (STL) fabrication system. The technology used by most 3D printers to date-especially hobbyist and consumer-oriented models-is fused deposition modelling (FDM), a special application of plastic extrusion, and the first FDM machine came in 1992. Many other methods for AM were developed subsequently but the technology did not come into manufacturing industry in a big way until the last few years and now we seem to be on the cusp of a 3D revolution. 3D printing industry is expected to grow from $12 billion in 2016 to a $26.7 billion industry by 2019. By 2019, 10% of spare parts for cars, trucks, bicycles and motorcycles, as well as military vehicles and drones, will be 3D printed in countries like the US who are the world leaders in this technology.

Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although the time varies widely depending on the type of machine used and the size and number of models being produced simultaneously. Traditional techniques like injection moulding can be less expensive for manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and less

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expensive when producing relatively small quantities of parts. Seemingly paradoxic, more complex objects can be cheaper for 3D printing production than less complex objects.

AM Process

In AM process there is far more value for digital design and end product rather than the process itself. The process basically consists of a computer design, processing, printing and finishing. 3D printable models may be created with a computer-aided design package, via a 3D scanner, or by a plain digital camera and photogrammetry software. 3D scanning is a process of collecting digital data on the shape and appearance of a real object, creating a digital model based on it. A diagramatical explaination of AM is given in the fig below.

Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution and then removing material with a higher-resolution subtractive process can achieve greater precision. This is called finishing.

Types of 3D Printing Processes As seen in the fig above, printing is the revolutionary part of AM

technology. A large number of printing processes are available. The main differences between processes are in the way layers are deposited to create

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parts and in the materials that are used. Each method has its own advantages and drawbacks, which is why some companies offer a choice of powder and polymer for the material used to build the object. The main considerations in choosing a printing machine are generally speed, cost (of printer and part), choice and cost of the materials, and colour capabilities. Printers that work directly with metals are generally expensive ($ 500,000/-). However less expensive printers ($ 2000/-) can be used to make a mould, which is then used to make metal parts.

Some of the important 3D printing methods are discussed below:-

Fused Deposition Modelling (FDM). The model or part is produced by extruding small beads or streams of mol ten mater ia l wh ich harden immediately to form layers. A filament of thermoplastic, metal wire, or other material is fed into an extrusion nozzle head (3D printer extruder), which heats the material and turns the flow on and

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off.

Laser Sintering Techniques. These techniques include selective laser sintering, with both metals and polymers, and direct metal laser sintering. Selective laser melting does not use sintering for the fusion of powder granules but will completely melt the powder using a high-energy laser to create fully dense materials in a layer-wise method that has mechanical properties similar to those of conventional manufactured metals. Electron beam melting (EBM) is a similar type of additive manufacturing technology for metal parts (e.g. titanium alloys). EBM manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum.

Material Jetting. Consists of an inkjet 3D printing system, which

creates the model, one layer at a time by spreading a layer of powder (plaster, or resins) and printing a binder in the cross-section of the part using an inkjet-like process.

Photo polymerization. Photo polymerization is primarily used in stereolithography to produce a solid part from a liquid. Inkjet printer systems spray photopolymer materials onto a build tray in ultra-thin layers (between 16 and 30 µm) until the part is completed. Each photopolymer layer is cured with UV light after it is jetted, producing fully cured models that can be handled and used immediately, without post-curing.

Applications of AM

The earliest application of additive manufacturing was on the toolroom end of the manufacturing spectrum. Rapid prototyping was one of the earliest additive variants, and its mission was to reduce the lead time and cost of developing prototypes of new parts and devices. However the technology has percolated into almost all fields of manufacturing.

Medical Science. Surgical uses of 3D printing-centric therapies have a history beginning in the mid-1990s with anatomical modelling for bony

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reconstructive surgery planning. Patient-matched implants were a natural extension of this work, leading to truly personalized implants that fit one unique individual. Virtual planning of surgery and guidance using 3D printed, personalized instruments have been applied to many areas of surgery including total joint replacement and craniomaxillofacial reconstruction with great success. The use of additive manufacturing for production of orthopedic implants (metals), hearing aids and dental industries is growing. Recently, a heart-on-chip has been created which matches properties of cells. Medicines and drugs are now being 3D printed.

Aerospace. In May 2015 Airbus announced that its new Airbus A350 XWB included over 1000 components manufactured by 3D printing. Printer for working in zero gravity at space stations is being tested.

Automobiles. In early 2014, Swedish supercar manufacturer Koenigsegg announced the One, a supercar that utilizes many components that were 3D printed. Subsequently, Strati, a functioning vehicle that was entirely 3D printed using ABS plastic and carbon fiber, has been commissioned.

Food. Additive manufacturing of food has been developed by squeezing out food, layer by layer, into three-dimensional objects. A large variety of foods are appropriate candidates, such as chocolate and candy, and flat foods such as crackers, pasta, and pizza. More varieties are being developed

Firearms and Ammunition. AM's impact on firearms involves two dimensions: new manufacturing methods for established companies, and new possibilities for the making of do-it-yourself firearms. The first 3D printed fireams were successfully tested in 2012 and now there are a number of small calibre weapons which have been 3D printed. Printed bombs and ammunition are also being tested.

Houses. China has already built a 3D house and some other countries are attempting the same.

Utility Items. Jewellery, furniture and practically almost every household item has been printed.

Sports and Clothing Items. 3D printing has entered the world of

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clothing, with fashion designers experimenting with 3D-printed shoes and dresses. Nike is using 3D printing to prototype and manufactures the Laser Talon football shoe for players of American football, and New Balance is 3D manufacturing custom-fit shoes for athletes. 3D printing has come to the point where companies are printing consumer grade eyewear with on-demand custom fit and styling. On-demand customization of glasses is possible with rapid prototyping.

Educational Models. Higher education has proven to be a major buyer of desktop and professional 3D printers. Libraries around the world have also become locations to house smaller 3D printers for educational and community access.

Vehicle and Aircraft Parts. AM is beginning to transform both unibody and fuselage design and production and powertrain design and production. For example, in 2017, GE Aviation revealed that it had used design for additive manufacturing to create a helicopter engine with 16 parts instead of 900, with great potential impact on reducing the complexity of supply chains.

MuseumsMuseums have purchased 3D printers and actively recreate missing pieces of their relics. 3D printed sculpture of the Egyptian

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Pharaoh Merankhre Mentuhotep has been printed by an on line 3D firm called Threeding.

India and 3D Printing

India is relatively new to 3D printers and not much headway has been made in this field till recently. Most of the established industries follow conventional approach of modeling through CNC machines as large format 3D printers are expensive and cost almost same as that of conventional machines, which raises reluctance among industrial consumers to opt for 3D printing. However, with increasing initiatives by domestic manufactures, 3D printers are now available at affordable cost to consumers.

The applications of 3D printing for India are in the field of electronics, automotive, medical, architectural, aerospace, educational, industrial, and others. India 3D printer market revenue is projected to reach $46 million by the year 2019. With the advancements in technologies, new printing material development, evolution in design software, and 3D scanning devices, the use of 3D printing in these applications is further likely to develop.

Globally established companies such as Stratasys and Optomec have partnerships or alliances with India based technology companies for increasing their customer base. Major players active in India 3D printing market (including manufacturers and distributors) space are Altem Technologies, Imaginarium, Brahma 3, KCbots and JGroup Robotics. Another interesting concept spinning up in India is 3D design marketplace and df3d is pioneering in this domain. Renshaw has opened a new Additive Manufacturing Solutions Centre in Pune. Equipped with the latest additive manufacturing systems from the global engineering firm, the new facility will provide a secure development environment for customers to expand their knowledge and confidence using AM technology.

M Tech courses in AM have been instituted in some IITs wef 2013. However no policy/guidelines for AM have been promulgated by the government as yet.

AM in Global Armed Forces

The militaries of US, China, Israel and UK have made significant

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headway in AM applications for their requirements. A case in point is the military exercise conducted in Chengdu region of China in 2016 where a few tatra trucks caught fire. A coupling of one the trucks was damaged and the same was not readily available. This part was printed by a 3D printer which was available in the exercise area. The part was attached to the tanker, and after numerous tests the PLA confirmed that the tanker was now in perfect working order, ready to resume normal operations. PLA has been testing various other 3D printed parts as well, including ratchets, shafts and gears whereas Israel has started using printed parts for drones. However US has taken the lead as far as applying AM in armed forces is concerned.

A Principal investigator has been nominated for materials and technology development in AM at the US Army Research Laboratory (ARL). The U.S. Navy has permanently installed a 3D printer on a warship. The crew has been making everything from disposable medical supplies, to a new cap they designed for an oil tank, to model planes to move around their mock-up of the flight deck. Sciaky and Lockheed Martin have already produced test parts for jets. In 2015, a Royal Air Force Eurofighter Typhoon fighter jet flew with printed parts. 3D Printed Uniforms with exo-skeleton are being tested. Researchers are developing an embedded radio antenna on the side of a soldier's helmet or an article of clothing.

Rather than trucking or airlifting in antennas for the growing number of Internet of Things (IoT) connected devices, US is studying ways to print dielectric antennas, even from non-conductive materials like ceramic or plastic, directly on location. Research is on for different approaches for 3D printing high-frequency circuits and electromagnetic devices. FALCom is a 3D printing process being developed by ARL. It is based on the use of composites, where scientists can engineer advanced composite cement, fiber-reinforced polymers, metal composites and composite ceramic and metal matrices, all of which can be tailored for use in the field. Food technologists are testing 3D printing applications for food processing and development within the Combat Feeding Directorate.

US is looking at futuristic use in the CBRN field - Larry Holmes, principal investigator nominated for materials and technology development in AM stated "We drop a black box in a place where you wouldn't want to send your soldiers. It could be a biohazard area, a radioactive area, dense jungle, the top of a mountain, a dangerous extreme environment, etc. Through a suite of sensors, this manufacturing unit senses what's around it,

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what minerals are in the sand, and what trees are around it. It then prints robots to go collect those materials."

Army Co-Creativity and 3D Printing Concept. The US Army has created a crowdsourcing website, called Army CoCreate, where anyone can identify problems facing the Army, design a prototype solution and upload it. Army CoCreate is a proof-of-concept effort exploring the utility of crowdsourcing for army requirements and solutions. This platform also provides the inspiration for workshops called "Make-a-Thons," where Soldiers from an institute called Maneuver Center of Excellence try to bring virtual blueprints to life by manufacturing 3D prototypes.

Military Applications of AM for IndiaMilitaries around the world have been working on developing 3D

printing technologies, using 3D printing for prototypes, developing their own labs and using the technology in aircraft and other military vehicles. Though India's Armed Forces have made no headway in the AM field we can take lessons from these countries and make a start. Some such applications which may be considered are given in succeeding paragraphs.

Create Prototypes. 3D printing enables designers to skip the fabrication of tools and go straight to finished parts. And although printing a prototype part might take several hours, it is still significantly faster than building tools that are then used to fabricate prototype parts. This ability to quickly fabricate prototypes enables engineers to validate design concepts faster, speeding up the overall development process. Agencies like DRDO, Ordnance Factories, DPSUs, DGQA, etc may take the lead in this department.

Design Concepts & Mock-ups. Design and manufacturing engineers can use these prototypes as a tool to better communicate how a design looks, feels, and operates allowing for the product design to integrate with manufacturing at an earlier stage in the development lifecycle.

Small Volume Production. Certain low-volume, weight-sensitive products are opening up additional opportunities for 3D printed parts. These need to be identified and the 3D printing of these can be de-centralised to appropriate levels.

Produce Clothing and Wearable Sensors. The global industry is researching the use of 3D printing to produce combat uniforms with rigid

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areas for protection but with flexible areas around joints for movement (which is hard to accomplish with a regular textile), that would also eliminate a lot of seams in clothing, making it more comfortable and less likely to chafe. 3D printing will allow the Indian defence industry to produce less expensive armour and custom clothing designed for specific jobs like IS duties. It could also allow for incorporating ballistics materials and sensors into clothing. Advanced suits and exoskeletons to augment soldiers' physical capabilities on the battlefield can also be developed.

Print Food. Researchers at DRDO must work in conjunction with ASC and its equivalents in other services to adapt and food printing technologies for the Armed Forces. Among the benefits are that it would cut costs and it could allow soldiers to include specific nutrients they might be lacking due to terrain or geographical restrictions.

Reducing Logistic Chain. AM technology may well have a significant impact on how the military provides special tools, custom parts and replacements for obsolete parts to deployed soldiers and sailors, who are often at remote locations or on ships. In any significant deployment, an untold numbers of parts, tools and spares add up to comprise a military logistical tail. These costs add up, when you add all the transportation costs, fuel, security, it then might be cheaper and reliable to be able to print one.

Treat Injured Soldiers. The printing of medicines and other life saving medical equipment in field areas will improve causality response time and reduce logistic chain.

Potential Advantages of AM for India's Armed Forces/ Defence Industry

There are several potential advantages of AM for India's Armed Forces/ Defence Industry. Reduced manufacturing cost and rapid prototyping and easy transition from prototype stage to large scale manufacturing. Conformal designs & better interior volume utilization of military equipment and hardware which will lead to reduction in size and weight. Components like sensors, antennas, fuzes, etc will be more affordable and readily available. Mission tailored equipment and products can be produced with respect to physical characteristics like weight, strength, water resistance, etc which can be increased or decreased. Production can be direct from CAD to prototype and material for

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printing can be chosen as per performance required. Versatile and wide variety of equipment can be produced which can include electronics, electromechanical, optoelectronics and power sources. Faster and flexible production as there can be a virtual factory in a truck, fabrication in a theatre and just in time. More immunity to obsolescence as parts for keeping old fleet serviceable can be produced on demand, where and when required through AM.

Improved functionality through embedded electronics by electronic printing. Electronic printing uses an inkjet printer to print electronic components such as munitions antennas, fuse elements, and batteries. This process allows engineers to potentially print sensors directly onto a weapon or even an article of clothing. For instance, a radio antenna made of silver nanoparticles printed onto a flexible polyimide substrate could be embedded in a soldier's helmet. Similarly, electronics could be printed on the side of artillery guns, freeing up space inside.

Increase the reliability of Supply Chains whose aim is to provide 'right part at right place at right time and in right quantity'. Digital supply chains through AM will eliminate the need for large, centralized production facilities to achieve economies of scale. AM also reduces the need to forecast supply chain capacity accurately. Digital supply chains that use universal raw materials should be more resilient and easier to reconstitute in the face of actions by adversaries. In addition, by eliminating the need to transport and inventory parts and products, digital supply chains open up the possibility of realizing higher operational readiness and sortie rates.

In the tooling industry, AM has the ability to lower costs, shorten lead times, and produce complex geometries enables the fabrication of multiple individual tooling pieces needed to customize parts. Extrapolated, this increased ability to customize parts has the potential to positively influence unit agility. Enabling customized, on-demand parts effectively disintermediates the physical inventory that the military's supply chain provides and upon which individual units were traditionally reliant.

AM enables product designs and dimensions that would be hard to create through traditional manufacturing, and thus transcends existing design and manufacturing limitations. Also its potential to reduce the number of parts in an assembly positively affects supply chains and drastically reduces production cycle time.

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Hurdles to Overcome

Although the adoption of digital supply chains can improve mission performance and increase operational efficiency and effectiveness, designing and implementing a digital supply chain present a number of challenges. The most important challenges are outlined in succeeding paragraphs.

Parts Testing and Qualification. Certified materials and printers to make qualified metal parts don't exist in today's Army. The unique benefits of rapid build time and unique microstructural control offered by AM processes cannot be fully realized with existing quality certification methods. A workable quality certification model needs to be developed and this may well become the tipping point in the adoption of AM technologies.

Information and Communications Security. If AM parts are made on battlefields where lives are at stake, the security of the designs of those parts is paramount. Cyber security is essential to prevent enemy forces from interfering with our digital supply chains.

Infrastructure, Training and Development of Necessary Skill Sets. To completely exploit AM infrastructure, mainly printers and accessories, is an essential pre-requisite. Considering the colossal amount of printers required for complete implementation of AM, the requirement will inevitably have to be phased and prioritised. Training and development in the manufacturing and design skills required to exploit these new capabilities need to be developed and integrated into military occupational specialties or the civilian work forces. AM specific skills are necessary in CAD design, AM machine making, operation, maintenance, raw material preparation and management, analysis of finishing, supply chain and project management. A significant portion of the necessary training will be on the job.

Intellectual Property Issues. 3D printing has existed for decades within certain manufacturing industries where many legal regimes, including patents, industrial design rights, copyright, and trademark apply. However, there is not much jurisprudence to say how these laws will apply. Where an active intellectual property is involved, agencies/organisations would have to contact the owner and ask for a licence, which may come with conditions and a price.

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Legal Issues. Legal issues regarding patents, trademark and copyright need to be fully clear before venturing into this field. There is not much clarity on who will be liable, where and under which law as the product can be designed in one country and printed in another, using the printer of a third country and the raw material of a fourth. Pin pointing responsibility for failures, accidents and quality certification due to the decentralised production of AM products may be difficult. Digital fingerprinting and branded data files will be the norm which our Armed Forces must get used to.

Change Management. Armed Forces in general and logistics echelons in particular need to be mentally ready to face the challenges posed by transition to AM supply chain. Requirements of infrastructure and printers (it must be kept in mind that all printers cannot print everything and a number of different types of printers may be required depending on type and size of end product desired), range and depth of stocks may need to be reworked if printer and raw material is available, margin between stock and raw material will be blurred and nucleus of trained personnel to perform AM jobs will need to be positioned at say brigade or unit levels. Governance plans to manage all AM activity in the organization need to be made. Training plans for all military occupational specialties that will participate and capacity plans for all AM machines involved are essential pre-requisites. Risk management plans that address challenges such as intellectual property, cyber security, and part certification will also be required. Large scale of involvement of private sector is inevitable, at least in the initial stages of the transition as they have the expertise in AM presently. This involvement may be down to lowest formations/units in the teething phases.

The Way Forward

Increase in knowledge regarding potential of additive manufacturing with higher decision makers at both MoD and the three services is the start point. Only when senior functionaries are convinced can the transition to AM process be driven with any conviction.

Since no clear cut policy exists on AM, a policy/road map/guideline to be laid down to exploit additive manufacturing techniques in Armed Forces. A lead agency must be nominated to drive AM processes and major stakeholders be identified. The lead agency must address all challenges

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mentioned above. Legal position on printing restricted items needs clarification from the government. Information, cyber and communications security issues regarding AM to be clarified. Feasibility study/research for institutionalisation of additive manufacturing in defence forces wrt infrastructure, HR, training and other issues also may be carried out.

Pilot Project. A pilot project for may be initiated based on the feasibility study before full scale implementation. This pilot project, in addition to taking military requirements into account, should consider the points in the supply chain where AM will have the greatest impact and make a data base. Once the data is compiled, organizations can use a value engineering approach to determine which AM process could be used to produce each part. Parts can then be grouped by AM technology. Based on the depth of the part's requirements, the organization can determine the number and type of AM machines needed. These details can then be added to the database. With a parts database in hand, the organization can conduct comparative testing of parts produced by both traditional and additive means. Before doing so, commanders must establish prioritisation criteria to arrive at the best candidates for AM applications. Once the criteria are established, performance testing can identify various failure modes and their acceptable limits. These tests should validate part/platform performance in both historical and future scenarios and demand patterns, as well as risk and disruption scenarios (that is, combat and field environments). These tests will generate new learning that can inform, and potentially improve, the design and functionality of the original part. Once the outcomes of tests are standardized and normalized and the organization has concluded that a given part should be produced using AM, the organization must design the digital supply chain. The digital supply chain will house a digital "inventory" of designs that can be secured and accessed anywhere and at any time. Assuming that there will be a number of initial potential AM applications, those with lower levels of risk and higher impact should be at the top of the list. When the organization develops expertise with the AM machine in the pilot, it can then pilot additional AM machines in other applications.

Conclusion

The potential impact in scaling advanced manufacturing across the defence enterprise cannot be overstated. We are at the dawn of a new age-a manufacturing renaissance-that will influence a world order whose outcome will be determined by those best able to take advantage of the

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potential it offers. While there is much uncertainty about where and how AM technologies will be used, one thing is certain: India's adversaries will not hesitate to take advantage of them. Will we?

*Col Harpreet Singh is a Senior Fellow at the Centre for Joint Warfare Studies (CENJOWS), New Delhi

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