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Where are all the 3D printers we were promised?

Is 3D printing really “green”?

Annalisa Plaitano, science communicator
On March 31st, 2021 |
3 mins reading time

Paolo Minetola
Paolo Minetola
Associate Professor in the Department of Management and Production Engineering (DIGEP) at Politecnico di Torino, Italy
Fabien Szmytka
Fabien Szmytka
Researcher at ENSTA Paris (IP Paris)
Bernardo Innocenti
Bernardo Innocenti
Professor of Biomechanics at École polytechnique de Bruxelles, ULB
Key takeaways
  • Benefits of 3D printing include customisation, on-demand production and reduced waste. If the objects are well designed, they are more resistant and last longer.
  • But the debate on the environmental aspects of 3D printing is more complex than it may seem.
  • Indeed, gas and particles emitted by the printing materials that are subject to high temperatures. They can be toxic for eyes and skin, with negative effects on the respiratory system.
  • The disposal of 3D-printed products at the end of their life also raises questions. In medicine, for example, it is still impossible to recycle implants and prostheses.

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.

3D print­ed met­al indus­tri­al objects 

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.