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