Americans consume approximately 84.3 million tons of plastic annually. Worse, waste generation stands at 73 million tons. Plastic use has tripled since the 1980s, and much of it doesn’t get recycled correctly or at all.
According to Statista, PET, HDPE, and LDPE/LLDPE are the three most recycled plastics. PP, PS, PLA, and PVC are barely or never recycled. The truth is not as much is recycled as is consumed. Here are Statista’s findings on recycling rates.
- 980,000 tons of PET (#1 – polyethylene terephthalate)
- 560,000 tons of HDPE (#2 – high-density polyethylene)
- 370,000 tons of LDPE/LLDPE (#4 – low-density polyethylene)
- 50,000 tons of PP (#5 – polypropylene)
- 20,000 tons of PS (#6 – polystyrene)
Other plastics, such as mixed plastics and PLA (#7), and PVC (#3 – polyvinyl chloride), are the most challenging to recycle. This results in their recycling rate being incredibly low. PLA is one of the best, however, for reuse in 3D printing. It requires special care, however.
With the rise of 3D printing for numerous innovative products, recycling plastic for printer filament is a smart way to reduce plastic waste. It’s a great solution to a global problem.
How 3D Printing Works
Before 3D printing even begins, you need the plastic filament (PLA). These thin threads of plastic are made in a plastic extrusion plant using this basic process.
- Clear or white plastic pellets are placed in a large blender and combined with additives, such as colorants.
- The new mixture is dried at temperatures of 140³F to 176³F.
- The dry pellets are loaded into a hopper.
- A filament extrusion machine comes up to heat
- Pellets are fed into the heating zone, where they’re melted.
- The melted pellets are pushed through the nozzle to form the filaments.
- The newly formed filaments travel through two water baths.
- The first shapes them into rounded filaments. The second water bath is cooler and sets the filament.
- Speeds are adjusted to make the filament’s diameter larger or narrower.
Finished filaments are collected on spools, much like sewing thread is stored on a spool. These spools are shipped to consumers and businesses for use in different 3D printers.
Once you have a spool of PLA, it’s loaded into your 3D printer, where it’s used to create something new.
- Build a 3D model on CAD software or select a completed 3D model from an online library.
- Convert that model to an STL file.
- Additional software breaks down the STL file into many different layers.
- The layers are converted into a set of printer instructions known as G-Code.
- Once the printer heats up, it follows the G-Code.
- FDM printers melt the plastic filament like an extrusion machine does. An SLA/DLP printer uses a laser or another light source to harden a liquid resin.
- The printer builds the item layer by layer.
- Once completed, the item needs to cool.
- A final cleaning of the newly printed item occurs. In some products, UV lighting might be used to cure the item.
Why Use Waste Materials in 3D Printing?
The heart of 3D printing revolves around the plastic pellets that are used in the creation of the printed item. The most common is PLA (polylactic acid). PLA is easy to work with as it’s strong, but it can be brittle. There are other types.
- ABS (acrylonitrile butadiene styrene) – Durable but requires special printing equipment
- PETG (polyethylene terephthalate glycol) – Ideal for waterproof applications, as it stands up to humidity
- Nylon – Tough and flexible, but harder to work with on an FDM printer
- TPU (thermoplastic polyurethane) – Flexible and resists impact
- PVA (polyvinyl alcohol) – Dissolves in water
- HIPS (high-impact polystyrene) – Usually paired with ABS
- Composites (carbon fiber, fiberglass, and Kevlar) – Strong and rigid, but only used with industrial 3D printers
When it comes to 3D printing, the most commonly used filament among consumers and businesses is PLA. It’s also one of the best, as you can recycle waste products from failed prints or filament scraps. Reuse keeps it out of the landfill.
Tips for Reusing Waste Materials in 3D Printing
The filament used in 3D printers requires special processing, making it unsuitable for recycling in curbside programs. Local municipalities may also not accept it.
There are mail-in programs, which are often the best choice. If you have the space and budget, companies sell the equipment needed to recycle filament. Desktop and industrial filament extrusion technology enables you to reuse your waste PLA for new items. If your business uses 3D printers, it might be a wise investment.
Some of the top companies selling shredders and extrusion technology include:
- 3Devo (Netherlands)
- Felfil (Italy)
- Filabot (USA)
Ventilation is important. Ensure your workshop or business has adequate ventilation equipment as well. It’s worth ensuring that ventilation is included in the extrusion package you purchase. Your package should consist of:
- Plastic shredder
- Filament extruder
- Water baths
- Spooler
- Fume extraction
Because packages usually fall in the $20,000 range, it’s unlikely hobbyists will want to invest in this equipment. For a business owner or school that prints a lot, making your own filament is worthwhile.
There are some challenges when using recycled PLA. It can be hard to maintain a single color across spools. One batch will be the same color, but it’s harder to ensure the next spool is identical. The material may need speed adjustments or a different temperature setting with each spool change.
When you make a batch of cookies, your next batch of dough won’t be identical. Humidity in the air, temperature of the ingredients, and precision in the cooking time all impact the outcome. The same happens with recycled materials. They’re good, but be prepared to make minor adjustments, and don’t expect materials to be identical.
The Future of 3D Printing
Some companies are already using filament recycling equipment to create new items.
- Audi – Turns plastic waste into 3D printed components like bumpers and radiator grills.
- Azure Printed Homes – Turns plastic bottles into 3D printed components that build backyard cottages and accessory dwelling units (ADUs).
- BMW – Collects and recycles old plastic fishing nets into trim for EVs.
- Mattel – Recycled ocean plastic is used to create filament for the Barbie Loves the Ocean collection of dolls.
Not everyone can afford or access filament recycling equipment. That doesn’t mean that plastic filament and 3D printing scraps should be thrown away. Find the right place for recycling.
Search materials on Recycle Nation to determine the appropriate place to recycle them. Not only do you get a list of nearby recycling facilities, but you also receive hours, phone numbers, and map directions. Use the recycling directory to make it easier to recycle plastics.
