3D printing is set to hit the battlefield

Fol­lo­wing the war in Ukraine, the French Direc­to­rate Gene­ral of Arma­ment announ­ced the crea­tion of a wor­king group dedi­ca­ted to “addi­tive manu­fac­tu­ring”, as revea­led by the press. Addi­tive manu­fac­tu­ring is a manu­fac­tu­ring tech­nique that com­bines desi­gn soft­ware and a 3D prin­ter. Whe­ther in indus­try or on the front line, the pro­cess is pro­ving attrac­tive to the defence sector.

Éric Char­ka­luk. This pro­cess is used by all branches of the armed forces (naval, land and air). Addi­tive manu­fac­tu­ring has been around in defence for about fif­teen years, ini­tial­ly in an explo­ra­to­ry phase. Today, it’s a prio­ri­ty for the Defence Inno­va­tion Agen­cy, and most indus­trial groups use it to make parts for land vehicles, air­craft engines and mis­siles. Lots of Euro­pean coun­tries are invol­ved, as is the Uni­ted States.

There are two main uses : manu­fac­tu­ring parts and repairs. Addi­tive manu­fac­tu­ring is used from indus­trial pro­duc­tion lines to the front line. In conflict zones, it can be very use­ful for quick repairs on the bat­tle­field or main­te­nance in rear bases.

Fabien Szmyt­ka. There are seve­ral pro­cesses and mate­rials used in addi­tive manu­fac­tu­ring, offe­ring a wide range of uses and pos­si­bi­li­ties. But in prac­tice, many repairs are car­ried out using com­mer­cial­ly avai­lable 3D prin­ters, such as those we are all fami­liar with ! Many poly­mer parts are manu­fac­tu­red in this way. All you need is a place to set up the machine and a power source. The raw mate­rial – liquid resin or fila­ment – is fair­ly easy to transport.

Metal addi­tive manu­fac­tu­ring could also be used, in which case the pro­cess is simi­lar to wel­ding. An ini­tial demons­tra­tor in a contai­ner has been tes­ted by the Euro­pean Defence Agen­cy. Howe­ver, this pro­cess is not yet reliable enough in its mobile ver­sion and is not cur­rent­ly used on the battlefield.

FS. For front-line repairs, addi­tive manu­fac­tu­ring allows mate­rial to be depo­si­ted on dama­ged areas or exis­ting parts, which is some­times impos­sible with other pro­cesses or results in signi­fi­cant varia­tions in the finish.

Added to this is the rela­tive sim­pli­ci­ty of the pro­cess. Take the example of a land vehicle, where a com­mon use case is damage to func­tio­nal com­po­nents such as door handles, which are par­ti­cu­lar­ly sus­cep­tible to impact. Howe­ver, it is not pos­sible to car­ry an infi­nite num­ber of spare parts on the bat­tle­field. 3D prin­ting makes it pos­sible to reprint a handle or any other com­ponent in a mat­ter of hours, requi­ring only the mate­rial and a machine. It is even pos­sible to adapt the geo­me­try of the spare part to make it more resis­tant for ongoing ope­ra­tions or to add func­tio­na­li­ty. The time and logis­ti­cal savings are significant.

EC. Mili­ta­ry vehicles some­times ope­rate in extreme envi­ron­ments : heat, sand, humi­di­ty, etc. Engine parts, for example, wear out very qui­ck­ly, and impro­ving main­te­nance is a real chal­lenge in theatres of operation.

EC. Yes, it also makes it pos­sible to add func­tio­na­li­ty to equip­ment, which is wide­ly used by spe­cial forces. In res­ponse to spe­ci­fic condi­tions in a theatre of ope­ra­tions, deve­lop­ments can be made very qui­ck­ly : for example, parts can be prin­ted to enable new wea­pon, obser­va­tion or mea­su­re­ment sys­tems to be fit­ted to a land vehicle.

EC. Prin­ted parts may have slight­ly dif­ferent pro­per­ties from those of the ini­tial parts, but this is not neces­sa­ri­ly a pro­blem, par­ti­cu­lar­ly in two situa­tions : those invol­ving parts sub­ject to low stress and those which can be kept in ope­ra­tio­nal condi­tion until the next main­te­nance ope­ra­tion. So, even if the ini­tial spe­ci­fi­ca­tions are not neces­sa­ri­ly met, there is no risk to users. It should also be noted that, thanks to years of labo­ra­to­ry research, prin­ted parts now have pro­per­ties very close to those of parts manu­fac­tu­red by more conven­tio­nal pro­cesses. Repair is the­re­fore still an active field of research.

EC. There is a real chal­lenge in terms of staff trai­ning. The armed forces are cur­rent­ly under­ta­king a num­ber of ini­tia­tives to train main­te­nance per­son­nel in the use of these machines. What’s more, addi­tive manu­fac­tu­ring is based on a dif­ferent approach to part desi­gn for which new gene­ra­tions of engi­neers are being trai­ned in this field.

FS. The other chal­lenge is acces­si­bi­li­ty and the geo­me­try of the part, but this is a pro­blem that affects many ope­ra­tors such as EDF, SNCF, etc. The plans for the com­po­nents are not gene­ral­ly sha­red due to indus­trial pro­per­ty rights. Without know­ledge of the geo­me­try of the part, it has to be scan­ned to recons­truct it, which makes the pro­cess more com­pli­ca­ted. Taking repai­ra­bi­li­ty into account from the desi­gn stage for pieces and com­po­nents would make it pos­sible to over­come this problem.

EC. Poly­mers are based on mature pro­cesses, and this is the only one wide­ly used by defence today. Pro­cesses using metal alloys ins­pi­red by wel­ding are being stu­died because of their repair poten­tial, and demons­tra­tors are being deve­lo­ped. Also, new pro­cesses are emer­ging, such as fric­tion stir addi­tive manu­fac­tu­ring for ligh­ter alloys (alu­mi­nium, for example).

Cera­mic-based pro­cesses are not cur­rent­ly used in repairs. This mate­rial is used, for example, in bul­let-proof waist­coats. But this appli­ca­tion would require major ups­tream stu­dies to be able to gua­ran­tee a zero level of risk in the event of repair using addi­tive manufacturing.

EC. A great deal of work is being done on the che­mi­cal com­po­si­tion of the filler mate­rials, because the mate­rials used in conven­tio­nal pro­cesses are not always the best sui­ted to addi­tive manu­fac­tu­ring. Teams are also wor­king on deve­lo­ping alloys that would enable a large num­ber of parts made from dif­ferent mate­rials to be repai­red, the­re­by redu­cing the num­ber of pow­ders or wires that need to be taken to the front.

FS. There is a real chal­lenge around the avai­la­bi­li­ty of mate­rials. Many high-grade mate­rials are not easy to reco­ver in a mili­ta­ry context. Research is the­re­fore being conduc­ted to use mate­rials that are easy to access and have the right pro­per­ties. But this raises the ques­tion of dura­bi­li­ty and mecha­ni­cal strength. When repai­ring a part with a dif­ferent mate­rial, there can be pro­blems with adhe­sion and the sub­sequent crea­tion of incon­sis­ten­cies that can cause damage.

Interview by Anaïs Marechal