PLA or Polylactic Acid is a polyester thermoplastic derived from corn starch, tapioca roots and sugar cane. This biodegradable material is a great for users of all levels of experience since it does not warp and has a pleasant aroma during printing. Although it is biodegradable, PLA will essentially last forever as long as you don’t leave it outside to the elements for an extended period of time (think two years). Unlike ABS, PLA does not require a heated bed and is much more forgiving during the printing process. Because of this, we highly recommend this material to new users as they build their 3D printing foundation and gain their bearings.
Polylactic Acid has a very high tensile strength which is great for high strength applications, but is also very rigid which makes it prone to snapping. Due to its low glassing temperature (the temperature at which the material becomes very malleable) of 70˚C, we do not recommend using PLA for parts in high temperature environments as their material properties will decrease significantly. As a whole, this glossy printing material is one of our favorites, and below you will find a few tips and guidelines on how to print like a pro with PLA.
Preparing for the Print
Before you start printing, it is paramount that your bed is leveled and your nozzle is adjusted to the right height. The nozzle should be close enough to the print bed that it pushes the filament onto the platform and allows it bond but not so close that it prevents the nozzle from extruding the material. Once you have properly calibrated your printer you can shift your focus to the nozzle temperature and your build platform.
While the Optimum Temperature will vary from printer to printer, we recommend starting at 215˚C and then iterating in increments of 5˚ until you dial in the optimum nozzle temperature. Below are some indicators to guide you on dialing in your nozzle temperature.
If the Nozzle of your printer is getting to hot the filament will become very stringy and will start to leak as the extruder moves between different sections of the print. If this happens lowering the nozzle temperature in increments of 5˚ until it stops. If you find yourself in the situation where your the nozzle is at the right temperature and you are producing high quality prints, but the extruder is still leaking, try increasing the retraction 3-4 millimeters in your slice settings and that will solve the problem.
When your nozzle temperature is too low there are a number of things that can occur. In extreme cases your nozzle can jam or get damaged because the PLA is not being heated at a fast enough rate to be pushed through the nozzle. If this happens raise your temperature from 10-15˚C because it is significantly low. In less extreme cases, if you notice that your print is has a rough surface finish and weak bonding between layers try raising the temperature in increments of 5˚C until you obtain a smooth strong finish.
Building the Foundation
For the critical first layer of your print we recommended using a slightly higher nozzle temperature to help build a strong foundation. Most slicing programs allow you to differentiate between the first layer temperature and the bulk nozzle temperature. By making this adjustment, you will create a stronger bond between the filament and the platform and improve the likelihood of attaining a successful print. After the first few layers, lower the nozzle temperature 5-10 degrees to the optimized bulk printing temperature.
A heated bed is not required to print with PLA, however if you decide to use one it will only enhance the quality of your prints. If you are using a heated bed, you do not need to apply kapton tape or painters tape because PLA will stick to the heated glass plate very well and will produce a smooth, flat bottom layer. The Optimum temperature to heat your bed is around 65 C. Again, the perfect temperature varies between printers so iterate until you find a temperature that produces a glossy finish to your liking.
If you are not using a heated bed, the most effective way to bond PLA to the print bed is to cover the platform in blue painters tape. Before you apply the tape, completely clean your print bed so there is no residue. This will keep a strong bond between the tape and the build platform and prevent the tape from peeling off as the plastic cools or when you pry off your part. When applying your tape make sure that the tape is laid flat on the platform without air bubbles and doesn’t overlap. After you have finished your print, make sure that none of the tape is damaged or out of place, if so, replace it with a new piece. One solid layer of blue painters tape should last 5-10 prints before needing to be replaced.
Quality and Storage
What you do with PLA after the print is equally as important as during the print. After you have finished the print clean your nozzle and take the roll off the printer and store it in a closed container. This will prevent your filament from absorbing moisture (PLA has an affinity for water) so it will maintain its quality for future prints. If your filament has absorbed moisture, the water in the filament will vaporize as it is being extruded and you will hear a popping noise followed by spurts of plastic spewing from the nozzle. Therefore it is paramount that you keep your filament in a humidity controlled environment to maintain the integrity of the material throughout the life of the roll.
Good luck and Happy Printing,
– The Team at 3D ProtoTech