Recycling of 3D printing waste

Additive manufacturing is strongly associated with the existence of a global economic market worth tens of billions of €/year, growing at a rate of around 20% a year. There are a number of reasons for the technology's success, ranging from the production of complex high-tech parts to very low-cost home and leisure applications. All processes are viewed favorably, as they seem to contribute to a sustainable economy: in principle, just the right amount of material is used to make an object. This very positive image, combined with the youth of the technology, has meant that the main concerns of researchers and industrialists have been focused on the ever-improving performance of the machines. It's only recently that users of very low-cost machines have turned their attention to the manufacture of fusible filaments from thermoplastic polymers, often household waste. It was only a small step to use another source of waste, that of parts considered defective. These parts are generally produced on a personal basis and hardly correspond to an economic market. Neither the preparation of the materials nor the quality of the parts produced meet very precise specifications. On the other hand, taking the example of 3D mechanical parts for the space industry, it is not possible to take the risk of using uncertified materials for obvious safety reasons. The notion of recycling therefore does not take on the same meaning, nor the same urgency, depending on the performance required (and the cost of the object in relation to that of the material from which it is made) of the part to be produced by additive manufacturing. It's a question of positioning oneself precisely in relation to a break-even point vis-à-vis a risk (of whatever kind).

This article on materials recycling deals with an emerging field, with some areas more developed than others for the reasons briefly mentioned above. Under these particular conditions, the author has drawn not only on scientific publications, but also on non-peer-reviewed grey literature (websites, for example). The analyses presented in this document have led him to :

• Review the different types of materials used in additive manufacturing;

• recall the effects of recycling on the quality of 3D parts;

• present current recycling technologies. For the moment, the major industrial players in the field have not invested in this market, and academic research on the subject is modest in number.

In addition, Google Scholar on the subject of "materials for additive manufacturing" lists over two million publications; the present document is intended to be more synthetic, considering only the main materials used.