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 naturally degrades when exposed to the environment. For example, an item made of PLA plastic in the ocean has a degradation time on the order of six months to two years. Compare this to conventional plastics, which take from 500 to 1,000 years to degrade. It is important to point out that although PLA will degrade in an exposed natural environment it is very robust when used in any normal application such as a printed toy or a critical piece of a printer. 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 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 (like the pictured water bottles) 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 80C 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 filament or some other material near the extruder. At MatterHackers we generally use PLA filament for all our printer parts except those that are directly around the extruder (such as the x-carriage, mounting plate and extruder block) which we print in ABS.
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 101 series that will help guide you in the right direction for getting a stellar first layer. View additional videos from this series.
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.
Blue Tape is not perfect but it is very easy to use and generally gives great results. However, sometimes your parts can pull the tape up off the glass during printing, and you will see some warping when that happens. To reduce the Blue Tape from pulling up, we have had great results putting Blue Tape on top of PET tape, but that's just crazy :).
NOTE: PLA will not stick well to Blue Tape when it is warm. You do not want to heat the bed if you plan to print on Blue Tape. Also, the surface of the Blue Tape will lose its ability to hold onto a part with use. You should replace the tape when you start to see the adhesion degrading (usually somewhere between 5-10 prints on the same spot).
When you have a temperature controlled bed, printing directly on glass can be a great option. The recommended bed temperature for PLA is 70C.
When you can get it working well, glass is the absolute best way to print PLA. It make a great shiny bottom layer and the heated bed ensures that parts stay nice and flat.
Many people have had success printing on Kapton Tape. To print PLA on Kapton Tape you need to have a heated bed. We used to print on Kapton Tape on a heated bed, but after mastering printing on glass we no longer recommend printing on Kapton tape as a first option. The procedure for printing on Kapton tape is nearly identical to printing on glass but involves more setup and clean up. For instructions on applying Kapton tape read this article: Bed Surfaces - How to apply Kapton Tape.
We have experimented briefly with Polycarbonate, oiling it slightly with vegetable oil. Polycarbonate did work, and the print came out fine. However the part was difficult to remove and the benefit was not readily apparent. We feel this method deserves more investigation and we'll update this section as we learn more. For now we recommend sticking with Blue Tape.
When working with a new roll of filament for the first time, we generally like to start out printing at about 205C and then adjusting 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 lot 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 extruder is not leaking so much material.
Sometimes you will have a material that is simply less viscous than other PLA and will leak more even at lower temperatures. We recommend you increase the retraction a few millimeters (3-4 seems like a good number for most every PLA we have tried).
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:
Note: We recommended removing the filament when soft rather than when fully melted so that there is less possibility of depositing melted material onto the extruder drive gear or leaving meterial high up the melt chamber entrance. Both of which can cause jamming and are hard to clean out. Soft removal also helps ensure that you get everything out of the extruder tip.
The Makerbot Replicators extruder is not quite as powerful as some of the RepRap geared extruders so here are some extra tips that can really help get great results.
|Color||Recommended Temperature||Recommended Range|
|Black||195c||190c - 210c|
|Glow-In-The-Dark||190c||185c - 205c|
|All Other Colors||210c||205c - 220c|
Note: You may need to experiment with the temperature that will print the best on your printer. Ambient temperature, humidity and the calibration and uniqueness of your printer all play a part in how your prints will turn out.
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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