Is 3D Printing A Clean Technology?
January 25th, 2021 by Jennifer Sensiba
I recently picked up a Creality Ender 3, a budget 3D printer. With the kids out of school and most opportunities for enrichment closed for the COVID-19 pandemic, our family needed something fun and educational to do at home. With the price below $200 (not including filament), it was almost a no-brainer. On the other hand, I wanted to make sure we weren’t going to cause problems for their future just to have some educational fun today, and this article is what I found when trying to answer that question.
I wish there was a simple yes-or-no answer, but like most things in life, it depends.
Additive vs Subtractive Manufacturing
The biggest environmental plus to 3D printing is how it works.
Most manufacturing methods are subtractive, meaning that they start with a solid piece of material (like plastic, metal, or wood) and then cut or burn away the parts that aren’t needed. This generates a lot of waste material that must then be thrown away in landfills (and may end up in the oceans), or processed to be used for more raw material,which requires energy to melt, pulp, or otherwise reform.
3D printing, also known as additive manufacturing, does the opposite, and in theory produces no waste (more on this later).
The 3D printer I got uses a spool of plastic filament for raw material. It’s like very thick (1.75mm) fishing line, and comes in 2 kilogram spools. The printer pulls the filament off the roll and shoves it through its “hot end,” which is a nozzle that works like a hot glue gun. This nozzle is moved around in three dimensions with stepper motors, gears, and belts, and it deposits the melted plastic in thin layers. It stacks these layers to produce whatever shape you program the machine to make.
I haven’t assembled my 3D printer yet, but here’s a timelapse video my brother made of his printer. You can’t see the nozzle moving because each frame was taken when the nozzle was in the same position, but you can see how the layers stack to produce an item.
Most consumer 3D printers use plastic, but more expensive printers (usually for business/industrial use) can use metal and other materials for additive manufacturing. It’s a technology that’s quickly changing, improving, and dropping in price, so metal printing is likely going to happen at home in the future.
Waste Is Still Sometimes A Problem
Additive manufacturing makes less waste in theory, but that’s not always true in practice.
While established designs are usually easy to print, someone coming up with an original design can go through many attempts and changes before getting it right. Unless they share it on a site like Thingiverse or DEFCAD for others to print, the final design will happen only a few times, making for a pretty high waste to useful product ratio. For that reason, the sharing of useful designs should definitely be encouraged.
Another source of 3D printing waste happens when a design has too much overhang for the drying plastic to hold itself up. To overcome this, people have to use supports, or little thin legs and arms that keep the print from sagging. When the print is done and removed from the build surface, these supports must be pulled or cut away from the print and discarded.
On many sites where 3D print designs are shared and improved, you can see that early designs of a project often need a lot of supports. As the design improves, skilled designers often make little changes to the design to reduce or eliminate the need for supports. The most skilled designers think about this from the beginning, and often make designs that accomplish this from the outset.
One final source of waste is machine errors. This happens the most for new users who don’t know what they’re doing, but can happen to experienced designers whenever they make changes to their workflow. New types of plastic, machine upgrades, new machines, and complex designs can prove a challenge to people of any skill level.
The error issue will never go away, but can be mitigated somewhat through learning. To help minimize waste, I’ve been consulting with experienced people I know, like my brother. I’ve also been doing a lot of reading and watching videos to learn from other people’s mistakes. For example, I know from this video that I’m going to need a square when assembling my Ender 3 to make sure I get everything plumb when assembling the printer. That way, it won’t be crooked and mess up the prints.
3D printers use electricity to melt plastic or other materials when printing. Whether that’s a negative environmental impact will depend on where your electricity is coming from, like an electric car. If you’re producing your own solar energy at home, the impact of this will be minimal. If you’re using grid energy, the impact will depend on what mix of sources your local grid uses.
If you’re producing items to use locally, a 3D printer will reduce the need for shipping and manufacturing elsewhere, making for a positive impact. On the other hand, if you’re making items to ship to people, there’s no benefit there. Either way, the filament has to come from somewhere, so some shipping will be used.
When used industrially, 3D printed parts can have a great positive impact, especially in transportation. For example, a 3D printed auto part that’s hollow instead of filled with metal or plastic is lighter, and the part’s weight contributes to energy used over its lifetime just moving it around. Additive manufacturing also allows for increased complexity from one part, and GE has used this to great effect with its newest jet and turboprop engines. Not only has this enabled more efficient jet engines, but it has also allowed for simplified workflows, less supply chain complexity (and associated shipping costs), and fewer failures. All of these things lower environmental impact.
The impacts of all these improvements add up over time.
What About Plastic Pollution?
Like every other aspect 3D printing so far, it depends.
The most common material used in home printing is PLA, or polylactic acid. Most choose to use it because it’s easy to work with and is relatively strong, but it’s also very brittle compared to other types of plastics. Despite drawbacks, it’s very forgiving of minor mistakes and tends to make great prints in a greater variety of conditions.
Environmentally, its greatest advantage is that it’s derived from biological sources, often from plants like corn. Because plants take carbon dioxide from the air, PLA is mostly carbon neutral. Another advantage is that it’s biodegradable, but the degradation is slow at ambient temperatures. To really make it sustainable, you need to make sure the printed products end up being industrially composted or recycled instead of ending up in a landfill or in the ocean.
In a landfill or the ocean, PLA will eventually degrade, but that would take hundreds of years. However, the plastic is not toxic to organisms like other types of plastics. For example PLA is commonly used in medical procedures where something like a screw must be left behind. It slowly degrades to lactic acid in the body, and doesn’t hurt the patient in the process.
Other types of common printing plastics don’t come from biological sources and aren’t biodegradable. They pose the same problems that any other plastic products pose after printing.
Industrial metal printing is probably more recyclable in the end, and that technology will likely come down in price later. This might eventually make 3D printing more sustainable.
Emissions From The 3D Printer Itself
Another negative impact of 3D printing comes directly from the printer itself. Studies have found that little bits of plastic and some volatile organic compounds end up in the air when printing, and breathing these in isn’t a good idea. Asthma and other breathing problems can be aggravated, and some of the emissions are known to be bad for everyone.
There are several ways to mitigate this issue.
The easiest thing to do is put the 3D printer in a case of some kind. The emissions only occur when the printer is running, and go away pretty fast after it quits. Casing the printer up in a plastic or wood box contains the emissions and protects nearby people. If one must open a case to check on the job, a respirator mask should be used.
Some workplaces put all of their 3D printers in a room and don’t allow workers to enter without a respirator when the machines are running. This is basically the same as the case approach, but on a larger scale.
Ventilation is another good approach to safety from these emissions. By keeping the air moving, or moving the air through filtration systems, you can keep the air clean for humans. Professional advice is recommended for filtration systems. Also, be careful to not create a drafty environment for the printers, as some types of plastics can warp or bend when cooler air blows across them during drying.
Summing It All Up
Like many technologies, 3D printing’s environmental impact depends greatly on the user’s choices. The design choices, sources of energy, types of plastic used, and whether the products are properly recycled all make a big difference. Workplace and home safety are also very important.
By making informed choices about all of these questions, the technology can be very clean. By ignoring the impacts or not getting informed, the technology can be fairly harmful.
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