Printing tricks

Get to know more about pla and how to print successfully

  • Monday, 30 November 2020
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Guide to Print PLA Everything You Need to Know

 

PLA (also called Polylactic acid) is a thermoplastic polyester. What makes it specials is that it’s usually based on renewable sources such as corn starch or sugarcane.

PLA properties

The renewable base allows PLA to be one of the fully degradable plastics used in 3D Printing. Although it will degrade, it’s not like live fruit or bread. In optimal conditions it can take around 6-24 months for PLA to be broken down.

PLA is one of the most common materials in 3D Printing for a few reasons. It’s main benefit is the lack of warping. PLA shrinks less when cooled down and for this reason it’s very easy to print with.

Printing with PLA also doesn’t create fumes or toxic gases like some other filament do.

The mechanical properties of PLA makes it stiff but brittle. A raw PLA blend will not flex  but rather shatter when it reaches it’s maximum load.

A common misconception is that PLA is weak. It’s actually pretty strong and stiff. The problem occur on repetitive stress and when the limit is reached.

 

 

 

 

 

 

What types of PLA are there?

Original PLA, PLA occupy 99% of the compound, others are colors processing additives. Hard, stiff, brittle, easy to break .

 

Flex PLA,PLA+,PLA plus, compounding with some elastomer to make tough and strong PLA.

 

Silk PLA, compounding with other plastic to make high shiny surface, silk pearl smooth .

 

Powder infill PLA, glitter PLA, galaxy PLA, copper/bronze/brass ,wood PLA, carbon-fiber PLA, etc

 

Composite PLA, compounding with some other similar properties and cheap plastic

 

Best Practices

These tips will help you reduce the chances of common 3D printing issues associated with PLA such as stringing, oozing, or under-extrusion.

The first step of any 3D print is to make sure you have a good leveled build plate!

It doesn’t matter if you’re using glue, Magigoo, PrintaFix, glass, PEI, Buildtak or something even fancier. If your build plate isn’t leveled, the PLA won’t stick good enough.

If you have a heated bed, make sure you level it when it’s around it’s working temperature to avoid it moving/warping slightly when the print starts.

You also want to clean your build plate from residue of the above products every now and then. When cleaning the plate you also get rid of fingerprints and oil from your hands that can decrease the adhesion between print and plate!

Use a low speed for first layer

Although PLA can often be printed at high speeds, the first layer needs to be slow. Try to stay at around 25-35mm/s, whatver that translates to in your slices (most use % of regular speed to set this value).

No Cooling on the first 3 layers.

To help the PLA stick extra well, avoid using part cooling on the first 3 layers. This helps bond the PLA to your plate and cool down slower. When the 3 layers are done, the machine can go up in both speed and cooling.

When you see you have good adhesion on the first layers you might need to tune the PLA your using for your printer.

All PLA is not created equal and therefor does not work with the same temperature on your extruder.

Usually you can go with whatever’s suggested on the spool (usually around 180-240C) and that will work just fine. Sometimes even black and white PLA from the same brand can require a few degrees up and down to work optimal.

 

Getting PLA to stick can be a combination of correct distance from the bed, bed surface material and 1st layer fan speed (off).

 

Fine Tune the Retractions to Prevent Oozing

One of the most common problems with PLA is oozing. Since the filament flows relatively easily when compared to the other materials, it has a tendency to continue flowing during travel movements at the end of a segment. This creates strings or hairs on your part, and dialing in your retraction settings is the best way to combat this behavior! Different brands of PLA and different printers may need slightly different retraction settings, so you may need to experiment to find the best value for your printer. You could try a different retraction distance for each 20mm section of the print and then pick the value that works best in the end. For more tips on how to reduce stringing and oozing.

Optimize Your Cooling Settings

Cooling is one of the most important aspects of printing with PLA. Having a dedicated part cooling fan makes a huge difference in the quality of the printed parts. The freshly extruded plastic needs to cool down below the glass transition temperature as quickly as possible. This will prevent the plastic from stringing and producing other artifacts. We recommend setting the fan to 100% throughout the print, except for the first 1-2 layers where you want to form a strong bond with the print bed.

Choose the Correct Extruder Temperature

This is a great tip for any filament, but is especially useful for PLA which often contains different combinations of additives depending on the manufacturer. These different additives can lead to variations in printing temperature between 190-230 degrees Celsius. If you are not printing at the right temperature this can lead to several print quality issues including oozing, stringing, and under-extrusion. PLA can also be combined with different fills like metal, wood, and fiber that give it different characteristics than a standard homogeneous PLA. These may require different settings or even different hardware. Be sure to check with the manufacturer of your filament to verify the optimal temperature to use for your specific filament. If you have trouble with stringing, try reducing this temperature by 5-10 degrees, which will help prevent the excess oozing. If you’re struggling with under-extrusion, try increasing the temperature by 10 degrees so that the material flows more easily through the nozzle.

When it comes to print speed, every printer is different and optimum settings will depend on what type of printer you’re using. However, printing PLA is usually good at any speed between 30mm to 90mm/sec.

 

 

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