Is 3D printing really “green”?

Accord­ing to Pao­lo Mine­to­la, asso­ciate pro­fes­sor of man­u­fac­tur­ing tech­nolo­gies at the École poly­tech­nique de Turin, “addi­tive man­u­fac­tur­ing is a green technology.”

“Each object is only made when need­ed so pro­duc­tion uses the min­i­mum amount of mate­r­i­al and does not require moulds or spe­cif­ic tools,” he says. “More­over, 3D print­ing extends the lifes­pan of objects pro­vid­ed that they are designed cor­rect­ly. We can man­u­fac­ture com­plex shapes, which are impos­si­ble to make with con­ven­tion­al tech­nolo­gies, and with enhanced prop­er­ties such as light­weight or bet­ter heat exchange.”

Eco­nom­ic benefits

Indeed, poly­mer 3D print­ing pro­duces very lit­tle loss or waste and, con­se­quent­ly, it saves the ener­gy usu­al­ly required for stor­age and pro­cess­ing. Fur­ther­more, the parts are often designed to be more light­weight (hol­low but resis­tant). Their use can reduce over­all car­bon foot­print; for instance, in every sec­tor the pro­duc­tion of these new struc­tures reduces man­u­fac­tur­ing times and costs, but also ener­gy con­sump­tion and green­house gas emissions.

In addi­tion, it is pos­si­ble to man­u­fac­ture parts on demand, thus avoid­ing over­pro­duc­tion and waste of resources. Shar­ing dig­i­tal mod­el­ling files for spe­cif­ic parts with relo­cat­ed fac­to­ries is a great oppor­tu­ni­ty: the pol­lu­tion gen­er­at­ed by pack­ag­ing and trans­porta­tion of equip­ment can eas­i­ly be avoid­ed. One can imag­ine, for exam­ple, that in the near future, each air­craft man­u­fac­tur­er will have 3D print­ers to hand that allow them to rapid­ly pro­duce spare parts with­out transportation.

Nev­er­the­less, things are a lit­tle more com­pli­cat­ed than that. The impacts of this new tech­nol­o­gy are not easy to assess, espe­cial­ly since 3D print­ing includes sev­er­al tech­niques and uses a range of dif­fer­ent mate­ri­als. Com­par­i­son with tra­di­tion­al man­u­fac­tur­ing is not always pos­si­ble and stud­ies on this sub­ject are still rare, espe­cial­ly with regards to the ener­gy con­sump­tion of the entire life cycle from begin­ning to end.

Tox­ic technology?

Some stud­ies are begin­ning to sound the alarm on the health risks linked to 3D print­ing, too. Gas and par­ti­cles emit­ted by print­ing mate­ri­als that are sub­ject­ed to high tem­per­a­tures can become tox­ic for eyes and skin or affect the res­pi­ra­to­ry sys­tem. These risks are known in the fields of indus­try and research and, as such, oper­a­tors wear pro­tec­tives masks, suits and res­pi­ra­tors, and have reg­u­lar med­ical check-ups. How­ev­er, these health haz­ards are less well known in non-pro­fes­sion­al envi­ron­ments, espe­cial­ly those of pri­vate users. What is more, uni­ver­sal­ly recog­nised spe­cif­ic ISO stan­dards do not exist yet.

Fabi­en Szmyt­ka, pro­fes­sor and lec­tur­er at the ENSTA Paris (IP Paris) works with plas­tic and metal­lic mate­ri­als. He points out the fact that these process­es can be used in sim­ple envi­ron­ments. “The metal­lic pow­ders that we use are very fine so we must fol­low strict pro­to­cols to avoid any risk of envi­ron­men­tal con­t­a­m­i­na­tion and haz­ards for users. More­over, the out­put of machines is low, and we lose a lot of raw material.”

“For poly­mers, we are con­duct­ing research with chemists from the CNRS, to devel­op recy­cled or bio-sourced poly­mers,” explains Fabi­en Szmyt­ka. “For instance, we try to com­bine them with flax fibres because the com­po­si­tion of com­mer­cial poly­mers and liq­uid resins is unknown due to indus­tri­al secrecy.”

A flawed end of life

Anoth­er prob­lem aris­es when 3D objects reach the end of their lives. So far, there seem to be a lack of plans to col­lect, store and recy­cle these new mate­ri­als of ‘unknown’ composition.

In the med­ical world, recy­cling of pros­thet­ics and implants is com­pli­cat­ed, main­ly due to san­i­tary and oper­a­tional rea­sons. “It is not pos­si­ble to reuse them because they are often cus­tom-made objects which would not be adapt­ed to oth­er patients. Either way, they would like­ly be dam­aged by con­ven­tion­al ster­il­i­sa­tion tech­niques at high tem­per­a­tures,” explains Bernar­do Inno­cen­ti, pro­fes­sor in bio­me­chan­ics at École poly­tech­nique of the Uni­ver­sité Libre de Bruxelles.

“For all these rea­sons, the use of recy­cled mate­r­i­al to man­u­fac­ture implants is not pos­si­ble for now. And the patient is enti­tled to receive the best pos­si­ble equipment.”

To con­clude, there is still a long way to go before we suc­ceed in devel­op­ing a com­plete­ly ‘green’ form of addi­tive man­u­fac­tur­ing. Nev­er­the­less, we can already bear wit­ness to its huge advan­tages com­pared to sub­trac­tive man­u­fac­tur­ing [cut­ting a shape out of a piece of mate­r­i­al]. Many design­ers are active­ly work­ing to antic­i­pate the entire life cycle of new prod­ucts, in the inter­est of a cir­cu­lar econ­o­my. Addi­tive man­u­fac­tur­ing will more like­ly rein­force con­ven­tion­al tech­nolo­gies by adding its qual­i­ties, pro­vid­ed that man­u­fac­tur­ers imple­ment new busi­ness mod­els, espe­cial­ly with the sup­port of nation­al policies.