Machine Design
Waste Not, Want Not in 3D Printing

Waste Not, Want Not in 3D Printing

Different approaches can be taken to get the most out of your 3D-printing materials, as well as reduce waste.

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It seems 3D printing is leaving a wake of failed prints and no-longer-interesting knick-knacks behind it. Known as a minimal waste process, additive manufacturers may need to find a place other than the trash can for old or fail parts if they want to continue to support that maxim. Fortunately, some companies are trending toward environmental plastics and processes to reduce waste in more than one way.

There can be a steep learning curve in 3D printing, and for fused-filament-fabrication (FFF) printers, it means failed prints. Once proficient, the FFF process can make handy prototypes to check form, fit, function, and even end parts. But what can you do with a failed print, post-consumer part, or used prototype?

Production of the ProtoCycler, which is capable of grinding and re-extruding plastics for 3D printing, began after a successful crowd-sourcing campaign.

Crowd-sourcing was able to raise over $100,000 in about a month to fund the production of the ProtoCycler. Extruding at 10 ft. per minute, the ProtoCycler produces a 1-kg spool of filament in about two hours. Other companies offer similar products; for example, Filabot allows anyone to make their own filaments and recycle plastic.

While ProtoCycler and Filabot are made to be more of a desktop solution, Refil is a company using a larger-scale industrial process to grind old car dashboards and recycle them into 3D-printable filament. With more cars using plastics to cut weight to satisfy environmental regulations, vehicles could serve as an unending feedstock of materials. There was no mention about pre-process cleaning techniques or accuracy to the filament’s diameter, which are factors that can affect print quality.

At Maker Faire 2015, Filabot displayed its offer multiple desktop solution, which allows users to extrude or pelletize recycled or new types of plastics.

Recycling Measures

Nonetheless, saving plastic from entering the trashcan and reducing the shipment of virgin polymer around the country is a step in the right direction. According to the EPA, in 2013, over ­­­­­33 million tons of plastic entered the waste stream. Only about 9%, almost 3 million tons, of plastic was collected for recycling. This doesn’t mean it was recycled, just collected.

With the thought of recycling and grinding, a new coding system needs to be adopted. The coding system, or the numeric labels one through seven, is limiting. China has a much more advanced system that some are pushing for the U.S. to adopt. There is a simple solution, at least for now, that printers can be adopted to help grinders and recyclers. Just add a label into the print of the part that indicates the material.

In an effort to reduce the polymers that sit in auto salvage yards, Refil streamlined a process to produce a post-consumer filament from vehicle dashboards.

A future concern is that printers are printing multiple materials with pick-and-place machines to offer complex, embedded, fully encapsulated products. This convenient design may make recycling more difficult. However, one shouldn’t shy away from change. Taking a lesson from packaging engineers, weak points and stress concentrations can be worked into the design of a part that can withstand operation forces, but have the ability to strategically break apart to better separate the product to reduce waste and facilitate recycling. For now, though, more companies are working hard to make 3D printing a truly minimal waste process by coming up with biomaterials.

Filaments

PLA and ABS are the most-used filaments in the FFF process. PLA is made from a sustainable feedstock, and is capable of biodegrading in commercial compost piles. The ability to biodegrade makes this material more difficult to recycle. However, given the right environment, it’s said to be able to degrade almost completely. I am skeptical, since once again it was more about marketing than science, but lately I have been impressed with what I have seen in 3D-printing materials.

The problem is, in general, that the easier a polymer biodegrades, the easier it can fall apart. We tend to like plastic for its ability to not fall apart. Plastics have great chemical stability, but now we see that stability is causing piles of post-consumer polymers in landfills.

A trend is to disrupt molecular bonds to add sustainable additives to polymer chains. The idea is that the sustainable additives will breakdown the plastic into smaller parts. Biodegradable polymers started with starches, common in PLA, and calcium carbonites. Companies today are looking to get back to where materials started and are finding ways of processing organic polymers. Plants are currently leading the developments in this niche market.

From Coffee to Algae

One of the more recent filament advances happened when 3DOM teamed with C2renew to develop Wound Up—a filament made out of coffee grinds. Finding value in waste streams is proving to be big money, and coffee by-product is just the tip of a growing industry.

Algae might be considered a waste, or a nuisance. But its ability to thrive in many environments, even polluted ones, gave 3D Fuel an idea to team up with a company that owns algae-polymer technology to harvest, dry, and process algae biomass to make a filament called Solasplast. The company hails it as a sustainable, biodegradable polymer that will work in commercial or industrial FFF machines. Harvested from fish farms and blended with PLA, the material is biodegradable in industrial compost.

The process is provisional, but the company might be taking advantage of the lignins in the algae. Lignins are known as the fibrous support material in vascular plants that help form cell walls—they’re rigid and tend not to rot easily. Other companies are catching on. For instance, a German company has launched BioFila, a lignin filament. Made from a sustainable feedstock, the company claims it’s 100% biodegradable. However, it wasn’t mentioned what, if any, environment was needed for it to degrade in.

New companies are finding value in waste streams, with the trend forming around plant-based materials. For example, Wound Up is a filament made from coffee grinds.

With so much plastic ending up in landfills, we need to consider biodegradation that can happen in such an environment. That was the goal of 3DPrintlife and Sierra Resins, which accomplished the feat. The ABS is still difficult to degrade, but the additive attracts the bacteria found in landfills, such as leachate, and breaks the polymer down into smaller pieces. The company says the bacteria will the attack the ABS.

As many companies start to see that materials must get back to its roots, literally in the case of lignins, the focus needs to shift to the viscosity and melt temperature of the materials to make sure they can be processed properly in today’s FFF machines. Otherwise we’re only adding more failed prints to the pile to be recycled.

 

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