Printing parts on the frontline

ADDITIVE MANUFACTURING (AM) is gaining increasing application in the defence sector as governments and militaries worldwide seek to implement innovative new ways of designing, building, and operating battlefield equipment across land, sea, and air.

There are several reasons why AM adoption is on the up. Firstly, the defence sector faces significant challenges around operational readiness – particularly when it comes to tackling obsolescence. Most ministries of defence globally have a vast fleet of ageing equipment, and budget constraints mean they have to make it last longer. Many systems date as far back as the 1980s, making it increasingly difficult to obtain the required parts. In some cases, the original equipment manufacturers no longer exist. Therefore, AM provides significant opportunities to 'print what you need', helping militaries overcome obsolescence.

Additionally, global trade friction has increased in recent years, further straining supply chains. There have been reports of European militaries struggling to source spare parts from prime contractors based in the US, with the lack of direct control over spare parts allocation leading to inadequate equipment availability. AM provides an agile solution to these challenges, enabling militaries to manufacture specific components on demand to maintain operational capabilities, placing them less at the whim of geopolitical constraints.

New parts at the push of a button

The growing interest in AM is apparent in many different armed forces in Europe. In the UK, for instance, the Ministry of Defence recently published an advanced manufacturing strategy that described AM as an exciting technology that must be urgently realised to deliver operational availability and improved supply chain resilience and efficiency.

The report provided an intriguing vision of the future. The authors teased a multi-pronged strategy starting at the component source, where parts are either designed for AM from the outset or reverse-engineered to enable a part that is no longer available to be additively manufactured. Meanwhile, a digital thread would allow the secure transmission of the information required to manufacture a part from a design library at the point of need. Mobile AM production units would provide a network of global manufacturing 'spokes' enabled through information sourced from designs delivered through the digital thread, with a return loop to allow recycling of material as part of a circular economy.

It is easy to see why the UK would be interested in such an approach. The MoD has an inventory of 1.3 million items and the report says that the opportunity for AM to provide an alternative supply source for obsolescent items is substantial. Even with the most deliberately cautious estimates, the report suggests that if 15% of the defence inventory were additively manufactured the net financial benefit would be £110 million over the next 15 years – with a net value per year thereafter of £ 35.5 million. That is a considerable amount of money, now and in the future.

A similar scenario is playing out in other major European countries. A recent article in the respected business newspaper Handelsblatt, entitled 'Ready to Defend at the Push of a Button,' discussed how the German armed forces are investing in 3D printing.

The Bundeswehr, for example, is testing 3D printing on board the frigate "Sachsen". According to the Handelsblatt article, the pilot study involved housing parts and brackets that frequently fail during missions, which were produced as spare parts on the ship. Production took place in high volumes, in rough seas and salt spray. Meanwhile, another project previously occurred at the Mazar-i-Sharif field camp in Afghanistan. A container printer was put into operation to produce components on-site. According to the article, the proof of concept was achieved with the printer functioning well in the heat and dust.

AM for prototyping and production

While the above developments are taking place at the frontline, defence manufacturers are also increasingly deploying 3D printers within their production facilities to increase flexibility and efficiency. The reasoning is clear: AM's inherent capabilities – building up polymer parts layer-by-layer rather than subtracting them from a metal block - provide significant opportunities for topology optimisation and assembly consolidation, which can lead to lighter and better-performing parts.

It also provides opportunities to quicken the pace of innovations and reduce lead times. For instance, the latest high-speed stereolithography printers, such as the Stratasys Neo800+, have been proven to reduce print times by up to 50% compared to the previous-generation. This enables large, accurate, and repeatable high-fidelity parts for uses such as wind tunnel testing, prototyping, and tooling. These machines also improve the surface quality of produced parts, meaning there is less requirement for post-processing.

So, let's look at what that means in action by diving into how and where AM is being deployed across the defence base. The first area is rapid prototyping, with defence suppliers using AM to create a broad range of polymer components such as brackets, clips, hydraulic cable covers and communications equipment more quickly and cost-effectively.

Electro-optic specialist 3E, for example, uses AM to produce a wide range of housings and cases for its monoculars, binoculars, and thermal imagers. This means its engineers can quickly move through different iterations of concepts and ideas, even building complete assemblies using environmentally durable materials such as Somos WeatherX for testing in the field. The company also deploys AM to create functional prototypes for trade show displays, saving money on shipping MIL-SPEC parts around the world.

Meanwhile, communication systems provider Spectra Group is a good example of a company using AM for prototyping – in this case, the Stratasys Origin One plus & Origin Two P3 Programmable Photopolymerization printers - allowing it to slash its outsourcing costs. The company had run out of a specific part for one of its tactical radio components. It was quoted £15,000 for new tooling to enable injection moulding of just six replacement parts. Instead, it used the Origin P3 machines to initially print the part, using Dura56 impact-resistant photopolymer as a prototype before being so impressed with the quality of the results that it used the printers for production-ready purposes.

Plenty of other companies have taken that step to using AM for production. Stratasys has been a long-standing player in the aerospace market, and many of its printers have a proven track record of consistency and repeatability using high-grade certified materials in the harshest conditions. That has allowed many defence suppliers to adopt the technology for military applications.

Defence prime Airbus, for example, has used AM to create ducts and casing for an enhanced air conditioning system (ACS) on the H145 twin-engine helicopter. Each ACS set now has 42 printed parts. Meanwhile, Germany-based communication specialist EANT has replaced large steel antenna mounts with 3D-printed variants, delivering a 38% weight reduction, 75% time savings, and 20% cost reduction.

Cost-effective approach to tooling

Finally, there is tooling. Some additive manufacturing techniques, such as Fused Deposition Modelling (FDM) and P3 Digital Light Processing, are used for tooling applications due to their wide range of versatile thermoplastics and photopolymers, which possess sufficient mechanical properties to do the job. For example, FDM polycarbonate can withstand compressive forces of up to 18 tonnes per square inch, which means it can stamp a broad range of metals such as hardened tool steel, tungsten and aluminium.

A key challenge for BAE Systems across its demonstrator programs or within future product development is the high non-recurring cost of aircraft tooling. The company increasingly uses FDM technology to reduce the costs of new products. This is especially true for items such as drill tools, repair tools and other development tools, which are often needed in small numbers.

Meanwhile, defence prime Northrop Grumman uses additive manufacturing to 3D print rocket motor tooling components that traditionally required metal fabrication, dramatically reducing production time from over a year to six weeks. Specifically, it printed a 10-foot-long rocket motor core mould tool in four large sections using Stratasys F900 printers and Antero 840CN03 polymer material, which has the necessary chemical resistance and electrostatic discharge properties required for safely moulding solid rocket propellant.

In conclusion, it is clear that AM is finding increasing applications in defence, both in the military for frontline part replacement and among suppliers for improving prototyping, production, and tooling processes. It is a reliable, flexible and cost-effective technique, making it suitable for multiple defence applications.

Stratasys has worked with numerous defence suppliers and armed forces worldwide and expects these partnerships to further enhance defence readiness, now and in the future.

Matthew Jones is defence technical lead EMEA at Stratasys

www.stratasys.com