Feb. 28, 2013
PLA is a wonderful, easy to use, 3D printing material. It is a renewable and biodegradable resource. It is non-toxic and has a pleasant smell when printing. PLA filament comes in a wide range of colors and because of its thermal characteristics, is particularly easy to get great prints with.
PLA or Polylactic acid is a thermoplastic polyester. It is commonly derived from renewable resources, such as corn starch, tapioca roots or sugarcane. One of the most attractive things about PLA plastic is that it is industrially compostable, which means it can be broken down back into its base elements through industrial means, and not through a ten thousand year lifespan. It is important to point out that although PLA is compostable it is very robust when used in any normal application such as a 3D printed jig or a manufacturing prototype. In that respect, you can think of it as being similar to iron. If you were to expose it to continuous moisture or leave it outside, it would "rust" and become brittle and unusable in short order. But if you had it in your home you would expect it to last nearly indefinitely.
PLA plastic is used in many industries from food packaging to biodegradable medical implants such as sutures, tissue screws, and tacks. PLA comes in a number of grades; scientific, medical, food safe, and then to the type of PLA used in consumer 3D printing. PLA's natural melting temperature is around 80°C but it is mixed with other plastics to make it suitable for 3D printing.
If you have printed with ABS filament, you will find PLA filament to be harder, wear more slowly, and be easier to get a nice flat part with. PLA is less thermally contractive and much easier to print big parts with. The thing to consider is that being stiffer and harder also means that it is more brittle. If the part you're printing will be used where it might receive a lot of banging or sharp collisions, PLA may not be the best material.
The other important consideration when printing parts with PLA filament is knowing what sorts of temperatures the part will be subjected to. PLA plastic becomes soft at 70°C - 80°C and will deform if used in environments that remain above those temperatures for any prolonged time. This is why you should use ABS or PETG filament at a minimum when you have a design that will be exposed to heat, even as little as the heat inside a car on a summer day. At MatterHackers we generally use PLA filament for all our educational models, test-pieces, and quick-turnaround prototypes, as they aren't going to face any stressful scenarios, they just need to look good.
The first layer is the most important part of any print. There are a few things you need to do to get the first layer to stick well.
Below is a video from MatterHackers' 3D Printing Essentials series that will help guide you in the right direction for getting a stellar first layer.
Blue Tape, or Painters Tape, is one of the easiest and fastest ways to get a great print from PLA. Here is a quick checklist of things you want to make sure you are doing.
When you have a temperature controlled bed, printing directly on glass can be a great option. The recommended bed temperature for PLA is 65°C.
When you can get it working well, glass is a fantastic way to print PLA. It's the only way to have a shiny bottom layer and one of the easiest ways to have a perfectly flat surface.
Kapton tape is a tried and true method that is in fact the default bed surface material for every Craftbot 3D printer. To print PLA on Kapton Tape you need to have a heated bed, with the procedure being nearly identical to printing on glass, it just involves more setup and clean up. For instructions on applying Kapton tape read this article: Bed Surfaces - How to apply Kapton Tape.
There are always new and exciting methods for bed adhesion being developed, so it's important to have a good grasp on what each method is best used for. You can check out our 3D Printing Essentials article about bed surfaces to fully understand the pros and cons of every bed surface you might come across while 3D printing.
When working with a new roll of filament for the first time, we generally like to start out printing at about 205°C and then adjust the temperature up or down by 5 degree increments until we get the quality of the print and the strength of the part to be in good balance with each other.
You will see more strings between the separate parts of your print and you may notice that the extruder leaks out a little bit of plastic while moving between separate areas of the print. If this happens you should try to incrementally lower the temperature by 5 degrees until the stringing is brought under control without compromising strength. If you just can't seem to get the stringing to stop, you might want to consider adjusting your retraction settings to increase retraction in increments of 0.5mm or so.
You will either see that the filament is not sticking to the previous layer and you are getting a rough surface (like the picture below), or you will get a part that is not strong and can be pulled apart easily. In either case, you should increase the temperature by 5 degrees and try again until you get good line segments on every layer and have a strong part when done printing.
When switching PLA colors:
There are a few key things to check when your prints aren't working. But before we look at solutions we need to have a brief description of your symptoms.
"I can't get the first layer to stick."
"The part has bad internal layers and top surfaces."
"The outside edges of my parts have lots of little bumps on them."
"Tall sections of my prints look melted or squished together."
"My printer will not put out any material."
Thank you for reading How To Succeed When Printing In PLA.
If you have any comments or contributions, please drop us an email or give us a call. We are always looking for tips, and best practices - and would love to hear from you. Feel free to reach out with any specific questions on the MatterHackers Forum.
Happy Printing! - MatterHackers
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