3D printing materials: Sustainable or not?

Among the various innovations that the profession of design engineering has experienced in recent times, the marvel of Additive Manufacturing (AM) is perhaps the one with the most influential nature. Here, Melissa Albeck, CEO of online materials database Matmatch, explores the latest developments in the industry and how environmentally sustainable AM actually is.

With AM techniques being widely adopted in industries worldwide, design engineering and manufacturing are undoubtedly being ushered into a new era of development.

3D printing is the most well-known of all AM methods, and it has taken off in recent years. The fact that it has given engineers the luxury of rapid prototyping is a testament to its revolutionary nature, enabling them to perfect their designs in every aspect prior to mass production.

However, regardless of the capabilities of this design process, engineers are still faced with the challenge of making it environmentally sustainable and cost-effective so that it can be adopted on a much wider scale.

One of the most common misconceptions regarding modern 3D printing is that only plastics are used in this process – but that’s simply not the case. Of course, resins are a popular choice as they offer a range of desirable properties like toughness or elasticity in solid form. SLA (stereolithography) and DLP (digital light processing) printers are common machines that are used to develop prototypes with resins.

Printable Materials

Modern design engineers, though, have a wide array of different printable materials at their disposal whose applications differ depending upon numerous factors such as the material properties required, cost, colour, appearance, and layer thickness.

Metal is a popular alternative material choice as metals can be directly printed using various techniques like powder sintering or direct melting. Metals like aluminium, titanium, and stainless steel are popular choices among engineers due to the high strength and metallic finish.

In fact, aluminium powder is often used to print fully functional parts as well as separated parts that are strong, precise and can handle details of 0.25mm.

Ceramics are another popular choice for engineers. Ceramics parts have been produced using porcelain, glass-ceramics, and aluminium oxide. Refractory ceramics like silicon carbide are even possible with the addition of proper sintering aids.

Advanced ceramics are used in the automotive industry, for small parts like filters or support mounts for catalysts for example, as well as in the biomedical industry.

More recently, glass has also been used in AM to build complex-shaped items that are crucial to fields like optics and microfluids.

Similarly, several organic materials are now also being used to develop materials for AM. They provide adequate quality and can offer environmental benefits. An interesting example of this is stone; powdered stone is combined with environmental-friendly thermoplastic polymer PLA (polylactide) which gives products both a natural look and texture as well as a strong structure.

As these examples show, it is quite safe to say that plastics are not the only materials that AM techniques utilise. What remains, though, is the question of sustainable materials that guarantee not only innovation in engineering but also a greener, more liveable planet in times to come.

The rise of 3D printing is bound to grow rapidly in the near future. A report by MarketsandMarkets estimates an astounding compound annual growth rate (CAGR) of 21.60per cent in the 5-year time period ending in 2021.

Sustainable Materials

With this growth rate, engineers need to develop environmentally sustainable AM materials quickly, and they have responded. Now some materials can be entirely dissolved in a solvent without any harmful emissions, like this 3D printed medicine.

The process used to create the medicines binds powdered medication with a water-based fluid, resulting in solid yet porous medications. Researchers are even developing materials for AM that are water-soluble, like these Poly(ether ester) Ionomers polymers, which means no special solvent is required and there are minimal material losses in the whole manufacturing process.

There is countless research being conducted with the sole purpose of obtaining printable materials derived from nothing else but natural products. Some of these natural products include very common origins such as algae and corn starch – things that grow nearly everywhere.

With materials being made out of natural products, there are massive environmental benefits. All of them are biodegradable and become a part of the natural environment once disposed of.

For example, bioplastics producer Saphium Biotechnology has developed PHA (polyhydroxyalkanoates)-based filaments that are non-toxic and biodegradable. Applications of the material, according to the company, include waste-less prototyping and garden accessories. But perhaps in the future this kind of material could have much wider applications.

Furthermore, there is a direct financial advantage in using such materials. Since most of them can be produced locally, without much expertise required, there is no need to expend resources in transportation and synthesis.

Bioprinting

Another ground-breaking application is in a field known as bioprinting, which involves the use of cells and advanced printers to fabricate biomedical items.

Swedish company Cellink specialises in the production of such AM printers and bio-ink; the ‘ink’ is made from cellulose sourced from forests and alginate that comes from seaweed. It can be mixed with human cells and, in the future, the technology may facilitate the creation of functioning organs – potentially helping to address the shortfall in organs available for transplants.

The Future

Regarding the future, such research is likely to produce results that get more attention from engineers concerned with the well-being of the environment.

From a materials selection vantage point, AM is really making significant progress. Polymers used to be limited to acrylonitrile butadiene styrene (ABS) and Nylon, but now 3D printing can be done with poly-methyl methacrylate (PMMA), thermoplastic elastomers, and even wood filament.

While there’s no guarantee as to how 3D printing will evolve, one thing’s for certain; the use of organic and compostable materials is likely to feature heavily. Especially as engineers and material scientists work towards new solutions to grow the gamut of materials for AM, that are not harmful to the environment.