Recycled 3D printing: Sustainable Solutions for Eco-Friendly Production

This paper reviews new approaches for making recycled 3D printing Materials more environmentally friendly using local and closed-loop recycling of thermoplastics and powders. The use of both post-industrial and post-consumer waste streams as well as renewable resources from agriculture by-products to feedstocks derived from plant based materials is explored. This paper covers sustainable approaches that entail whole lifecycle materials sourcing through recycling.

In this article, the author describes how shifting to more sustainable basic materials and techniques can make 3D printing a credible green tech. It looks at new opportunities to use recycled 3D printing and renewable material for AM. Relative to the sourcing, use, and end of use completion of materials, possible sustainable practices are also focused. The aim is to develop a set of current closed-loop best practices that can be used to define the most effective 3D printing recycling loop.

What is Recycled 3D printing Materials?

Recycled 3D printing also known as remanufactured 3d printing involves using post consumer and post-industrial waste in the feed for the 3D printers. Instead, it functions by converting recyclable thermo-plastics and other feed materials into filaments, powders or pellets ready for 3D printing of functional parts and products. Estimations of modern states predict that about 5-10% of the total used material pertaining to consumer level 3D printing comes from recycled resources.

Such recycled products include recycled versions of most commonly used 3D printing thermoplastics like PLA which is gotten from wastes from old electronic goods and plastics, ABS from used plastics and household plastics and PETG from wastes plastics packaging materials. These are then cleaned and shredded and extruded into filaments appropriate for use in 3D printers.

Benefits of Recycled 3D Printing

Reduced waste and landfill usage

Through this by avoiding the dumping of post- consumer plastics and other wastes in the existing and extremely scarce landfills, the recycled 3D printing plays a key role in shifting the environmental burden. What’s more, it promotes recycling of material that would otherwise be dumped in the dump sights.

Lesser dependence on virgin raw materials

Since recycled 3D printing filaments and materials are obtained from industrial and municipal waste streams, it lessens the need to extract new raw materials from the environment through energy-intensive mining or drilling processes.

Energy savings

The breakdown of recycled materials into 3D printer feed stock uses less energy as compared to extracting virgin materials, processing it and transporting it. Such a result in the end consumes much energy in the manufacturing process as well as within the life cycle of the developed product.

Common Recycled Materials for 3D Printing

Plastics like PLA, ABS, PETG

All of them constitutes a large percentage of the post-consumer plastic waste. Thus, their mechanical and thermal properties make them suitable for fused filament fabrication (FFF) type of 3D printing process.

Building materials like concrete, wood

Waste concrete and saw dust can be reprocessed and combined with binders to produce recycled concrete and wood filaments for 3D printing large structural parts.

Metals, plant-based fibers

Even 3D metal printing powders from manufacturing scrap and plant-based fibers from agricultural waste are now being converted into recycled 3D printing materials.

Future Scope and Challenges

Even though recycled 3D printing is gradually accepted more, it is possible to enhance the prospects of usage and environmental effects. Implementation of a different stream for every type of post-consumer plastic leads to improved percentage of recycling content in the 3D printed parts. The World Wide Web also holds promise because making standard policies for recyclability tests and certifications can also build consumer acceptance of the technology. However, quality and mechanics of the recycled filaments still present some issues with the general quality consistency.

Eco-Friendly Filaments for FDM Printing

Amorphous industry commonly refers to fused deposition modeling (FDM) type of 3D printers that use plastic, filaments material. Several filament types provide better solutions in comparison with conventional oil-containing plastics.

PLA

It is a polylactic acid (PLA) filament which is bio based material which means it originates from plant for example corn starch, tapioca roots or sugarcane. They are 100% recyclable in accordance with the standards of every European Union country; they can be decomposed and composted completely. At the same time, parts made from PLA material are strong but not heat resistant

PETG

PET glycol or PETG filament is derived directly from post-consumer pre-processed PET containers and bottles. It gives comparatively hard and shiny prints like ABS but are completely free from any sorts of emissions of toxic gases. PETG still stays strong for several years.

PC-ABS

The PC-ABS is a copolymer of polycarbonate and ABS that has acceptable impact strength, stiffness and can support significant loads. Filaments maintain up to 30% recycled 3D printing with raw material performance comparable to virgin PC-ABS.

Nylon

Nylon filaments like Nylon-6 could be created from rapseed oil or castor beans, reducing dependency on fossil oil-based nylon. They deliver resilient, tough prints suitable for functional prototyping and manufacturing.

Bamboo, wood, paper

These plant-based filaments leverage agricultural byproducts like bamboo powder, sawdust or paper particles bonded with bioplastics. The printed parts have a natural wood- or paper-like texture.

Food waste

Even food waste including grape and orange peels have been transformed into sustainable filaments via fermentation and compounding processes. Properties resemble common 3D printing plastics.

Recycled Materials for SLA/DLP and SLS/SLM Printing

Metal powder

Metal powders for selective laser sintering (SLS) and melting (SLM) can incorporate recycled 3D printing Contents like stainless steel, tool steel and aluminum from machining scraps. Properties match those of raw metal powers.

Polymers

Photopolymers reused for stereolithography (SLA) and digital light processing (DLP) 3D printing come from prototyping materials no longer needed. Performance remains equivalent to virgin resin ink though recyclability requires evaluation.

Composite powders

Powders combining recycled metals and ceramics show potential in SLS for functional parts. Hybrid materials achieve necessary strength along with sustainability benefits.

Properties of parts printed with both filaments and powders discussed above generally emulate the original raw materials. Mechanical qualities like tensile strength are also preserved through the additive manufacturing process with recycled 3D printing feedstocks. This confirms their viability for functional applications.

Overall sustainable additive manufacturing using post-consumer, post-industrial or agricultural waste significantly reduces environmental impacts compared to conventional manufacturing. With ongoing research in novel recycled materials, high-quality 3D printing is poised to become a greener technology.

Closed-Loop Recycling of 3D Prints

On demand, with 3D Printed utilizing fast prototyping and manufacturing, many a time failed or non functional prints are usually dumped into the waste bin commonly known as the land fill because of numerous challenges arising from mechanical shredding and reusing… This poses sustainability concerns due to use of energy-intensive virgin materials. Closed-loop recycling offers an effective solution by recovering various recycled 3D printing materials.

Issues with recycling failed prints

Failed FDM prints may contain infiltrated supports which interfere with mechanical recycling. Similarly, SLA resins cured with failed parts cannot undergo direct mechanical recycling due to cross-linking during curing. Powder-based materials also require special processing due to properties like oxidizability.

Chemical recycling approaches

New chemical recycling technologies can breakdown polymer, resin and powder prints at a molecular level. For instance, failed ABS parts ground to powder undergo depolymerization using chemical solvents to retrieve pure ABS monomers. These monomers can then be repolymerized for direct reuse as filaments without quality loss.

Resins from SLA/DLP printers are recycled 3D printing using similar depolymerization or solvolysis techniques, yielding clean photopolymers for re-use. Failed metal and ceramics parts from SLS/SLM may utilize acid leaching or precipitation to separate alloys for reatomization.

Reusing powders in SLS/SLM

Post-processing provides an alternative to chemical recycling for powder-based systems. Excess unused powder from SLS/SLM machines are simply recollected, sieved to remove impurities and reused without significant effect on properties or printing performance. This retains over 95% of material costs.

Closed-loop recycling establishes a circular economy for large-scale 3D printing materials by eliminating waste and dependence on virgin resources. With further refinements, the process is scalable for industrial and commercial users to realize fully sustainable additive manufacturing. Combined with sustainable input filaments and powders, it establishes 3D printing as a green manufacturing paradigm.

Local Sourcing of Recycled Feedstock

For a truly sustainable supply chain, recycled 3D printing materials should be sourced as locally as possible to minimize transportation emissions. Decentralized recycling models address this issue.

Small, community-based recycling facilities can collect post-industrial plastic scrap and post-consumer household waste locally. After basic sorting and purification, these plastics get converted into 3D printer filaments using small-scale extrusion lines.

The finished filaments are then distributed to nearby schools, libraries or businesses with 3D printers. As an example, a rural recycling initiative may collect farm equipment discs and household bottles within 50 miles to make PLA filaments used by local makerspaces.

This localized closed-loop system eliminates loads of plastic transportation. It also empowers communities to establish independent circular supply chains with minimum dependency on centralized virgin material markets.

Renewable and Biodegradable Materials

Sustainable 3D printing goes beyond recycled plastics to incorporate plant-based and biodegradable materials.

Resins produced from agricultural feedstocks like corn and sugar cane provide renewable alternatives to petroleum-based SLA resins. Composites using agricultural and forest residues like wood flour or hemp fibers further improve sustainability.

Bioplastics and bioresins ensure printed parts can safely degrade at the end of life without generating microplastics. When combined with local small-scale production loops, such renewable materials establish a net-zero manufacturing paradigm.

Green sourcing of feedstock and output of biodegradable parts are key to positioning 3D printing as an eco-friendly production method of the future.

Conclusion

Current improvements in 3D printing and materials used have made additive manufacturing technology the leading technology in the current manufacturing industry. However for 3D production to be sustainable the whole process from the material used to the final product should depict circular economy.
The strategies discussed in this article like using recycled 3D printing and renewable feedstock, closed-loop material recycling, and localized small-scale production help address sustainability aspects across 3D printing’s value chain. Widespread adoption of such green approaches can minimize dependency on virgin plastics, heavy transportation and non-renewable energy.

Overall, a shift to localized, waste-based and renewable resources establish recycled 3D printing as a manufacturing paradigm that is not only affordable and customized but also eco-friendly. This helps realize additive manufacturing’s full potential towards a sustainable future.

FAQs

Q: Can all 3D printing technologies use recycled materials?

A: While FDM and some powder-bed processes can use recycled 3D printing thermoplastics and metal powders respectively, other technologies like SLA may have issues with pre-cured resins. Ongoing R&D is expanding compatible processes.

Q: Is it really more sustainable than using virgin plastics?

A: Yes, reusing waste plastics significantly reduces environmental impact versus extracting new plastic from fossil fuels through energy-intensive processes. Even with some quality trade-offs, it is a greener alternative.

Q: How much does it typically cost compared to virgin filaments?

A: Recycled 3D printing filaments are usually 10-30% cheaper than comparable virgin filaments since material costs are lower. As recycling scales up further, prices are expected to reduce more.