Researchers from the Universidade NOVA de Lisboa (UNIDEMI) have highlighted a need for further research into circularity within the 3D printing industry.
Following an in-depth literary review, the team found that industrial waste is seldom re-used in 3D printing, and that little R&D has been done to address this. In particular, the researchers identified polymeric refuse as a recyclable material that could be used to both improve business profitability and reduce waste output.
“Plastic waste seems to be the material that’s often a point of interest in studies, and a few have identified possible avenues for having industrial symbiosis networks within the AM industry,” stated the researchers in their paper. “This could be more profitable and achieve a real positive impact on our planet.”
Is 3D printing eco-friendly?
3D printing has proven effective in recent years at enabling companies to embrace distributed production, and this in itself comes with environmental benefits. Using a single process to flexibly alter and manufacture complex products is inherently faster, and produces less waste, than centralized production techniques.
However, despite the efficiency benefits of going additive, there’s a growing industry consensus that more needs to be done to avoid ‘greenwashing’ the technologies. The AMGTA, for instance, recently found that in some cases, 3D printing has a higher carbon footprint (per kg of material) than its conventional counterparts.
Elsewhere, a Professor from the Massachusetts Institute of Technology has argued that in studies, too much emphasis is placed on energy expended, rather than the materials being processed. The UNIDEMI team took a similar approach in their paper and sought to explore the potential of material ‘symbiosis’ within 3D printing.
To achieve this, the researchers conducted a literature review, in which they investigated the current state of circularity-based additive research, and identified potential waste materials that could be used as fully-recycled feedstock.
Designing a more sustainable process
Despite combing through 32 studies, the researchers initially found that very little data exists about the nature of the waste produced during 3D printing. To narrow down their results into something quantifiable, the UNIDEMI team then applied a set of keyword algorithms, which left them with five papers as a basis for their review.
In one of the studies, a team from Michigan Technological University utilized a Gigabot X FGF system to test three ABS and PP feedstocks made from recycled polymers. Another of the projects, based at TU Delft, took a different approach and used a seafood firm’s wasted mussel shells as a ceramic-like 3D printing material.
Unsurprisingly, notorious open-source advocate Joshua Pearce was also involved in three of the five test cases, and each yielded usable 3D printing filaments. However, the team questioned the scalability of what they’d found, given that in the TU Delft project, for example, the private firm needed to sterilize the shells before shipping.
To make symbiosis more viable, the researchers suggested that whoever was responsible for material processing could commercialize it, forming an ‘industrial symbiosis network.’ Within these networks, the team theorized that a variety of wood, plastic, or metal-based materials could be adopted to 3D print end-use products.
Overall, the UNIDEMI group concluded that greater collaboration would be needed to develop such materials effectively, while financial considerations would be key to their adoption. With further research into circular printing, the team hopes that eventually new methods of addressing the UN’s sustainability goals can be found.
3D printing’s bio-materials
Although many popular photopolymers are still sourced from oil-based chemicals, researchers are increasingly experimenting with more sustainable alternatives.
Scientists from the Lithuania-based Vilnius University and the Kaunas University of Technology have created a recyclable resin for O3P 3D printing. The soy-bean based material is designed to replace petroleum-derived plastics within small batch production services.
A team from the University of Freiburg have also developed a novel environmentally-friendly material, but based it on the organic lignin polymer instead. According to the scientists, their biosynthetic filament has potential light construction or industrial applications.
Covestro, meanwhile, has commercialized its new Addigy range of sustainable filaments. Each of the polymers, which are specifically designed to address the circular economy, have either been constructed using recycled plastics or CO2.
The researchers’ findings are detailed in their paper titled “Waste Valorization through Additive Manufacturing in an Industrial Symbiosis Setting.” The research was co-authored by Inês A. Ferreira, Radu Godina, and Helena Carvalho.
The five research papers highlighted within the team’s literary review include:
- “Green fab lab applications of large-area waste polymer-based additive manufacturing”
- “Local and recyclable materials for additive manufacturing: 3D printing with mussel shells”
- “Circular Economy Concept In Additive Manufacturing”
- “Fused Particle Fabrication 3-D Printing: Recycled Materials’ Optimization and Mechanical Properties”
- “Mechanical Properties and Applications of Recycled Polycarbonate Particle Material Extrusion-Based Additive Manufacturing”
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Featured image shows one of the TU Delft team’s shell-based 3D printed test objects. Photo via the Materials Today Communications journal.