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