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.