3D printing : a solution for long-gone industrial parts

Could you explain what 3D prin­ting is and who uses it ?

Fabien Szmyt­ka. The sec­tors that use 3D prin­ting (i.e., addi­tive manu­fac­tu­ring) most are main­ly the manu­fac­tu­ring and trans­por­ta­tion indus­tries, aeros­pace and moto­ri­sed sports. These use 3D prin­ters to make machines, robot parts, spare parts, machi­ne­ry, casts, models, etc. The most fre­quent­ly used mate­rials are still plas­tic poly­mers in dif­ferent for­mats (pow­der, thread, etc.). Only a small part of the mate­rials used are metal­lic, cera­mic or other types.

In the auto­mo­tive indus­try, addi­tive manu­fac­tu­ring was first used a way to make pro­to­types, but today it is also used to make mecha­ni­cal parts as well as ele­ments of desi­gn (car body, spoi­ler, etc.). For ins­tance, car manu­fac­tu­rers like Hon­da have alrea­dy built vehicles com­ple­te­ly prin­ted in 3D, although they are not yet marketed.

The aca­de­mic world is also increa­sin­gly tur­ning to addi­tive manu­fac­tu­ring to sup­port research. Many pro­jects use expe­ri­men­tal pro­to­types made with 3D prin­ting tech­no­lo­gy. To this end, some labo­ra­to­ries or research ins­ti­tu­tions have equip­ped them­selves with their own prin­ters, or even Fab Labs (fabri­ca­tion labo­ra­to­ry) like those, for example, of the Ins­ti­tut Pas­teur (FLIP) or the Ins­ti­tut Poly­tech­nique de Paris.

What are the main advan­tages of addi­tive manu­fac­tu­ring in your field ?

Nowa­days, metal­lic addi­tive fabri­ca­tion makes it pos­sible to create com­po­nents with com­plex geo­me­try. These would be impos­sible to make by using conven­tio­nal methods. For example, very small details would break during demoul­ding in a clas­sic foun­dry. In some cases, wel­ding can be used to repair parts, but this tech­nique is very sen­si­tive to ambient condi­tions (air tem­pe­ra­ture, humi­di­ty) and very dif­fi­cult to auto­mate. You need many spe­cia­li­sed ope­ra­tors, who require much long trai­ning. Addi­tive manu­fac­tu­ring thus makes it pos­sible, to some extent, to make up for the lack of spe­cia­li­sed workers.

What does your research on metal­lic 3D prin­ting consist of ? 

Our objec­tive is to stu­dy metal­lic mate­rials pro­du­ced by addi­tive manu­fac­tu­ring. We use a spraying tech­nique based on metal­lic pow­der cal­led “Direc­ted Ener­gy Depo­si­tion” to make our own mate­rials. Their qua­li­ty depends on seve­ral para­me­ters : pow­der com­po­si­tion, power and speed of the machine. We then observe the effects of the varying these para­me­ters on the micro­struc­tures of the mate­rial. Final­ly, we test the resis­tance of this new metal­lic mate­rial to mecha­ni­cal stress. For ins­tance, we eva­luate the strain pro­du­ced by trac­tion, or mea­sure the effects of heat treatment.

In our labo­ra­to­ry, we conduct tests on com­plex struc­tures clo­ser to the geo­me­try of indus­trial parts, while stan­dard tests use a sim­pler geo­me­try (plates, cylin­ders). Our research on metal­lic mate­rials tries to meet the demands and needs of indus­trial part­ners. For example, they can ask us to deve­lop a mate­rial in com­pliance with deter­mi­ned cha­rac­te­ris­tics for a spe­ci­fic use. We also lead research stu­dies on poly­mers in col­la­bo­ra­tion with che­mists from the CNRS.

In what fields are your stu­dies applied ? And who are the final users of these materials ?

One of the most pro­mi­sing areas of inves­ti­ga­tion is the use of these pro­cesses to repair dama­ged struc­tures. To deve­lop appli­ca­tions for these metal­lic mate­rials, we work with the ener­gy, trans­por­ta­tion and aero­nau­tic sec­tors. For example, our part­ners EDF and SNCF use parts with very large dimen­sions. Their desi­gn some­times dates back to near­ly twen­ty years ago and, as such, they are very dif­fi­cult to replace since they are not pro­du­ced any­more. Hence the need to find prac­ti­cal and cost-effec­tive solu­tions to repair them.