Polylactic acid (PLA) is a popular 3D printing filament commonly used for prototyping, but also for arts, toys, educational projects, and household items.
This biodegradable material is one of the easiest filaments to print with, and it is a good choice for beginners. However, getting its temperature just right is crucial for project success.
The melt temperature of PLA ranges from around 150°C to 180°C. Factors that affect it include the specific formulation of the filament and additives used in the production of PLA material. The molecular weight and type of extruder can also affect this range.
It must also be said that PLA’s melt temperature is not the same as the extrusion temperature. Like all FDM printing filaments, PLA must be heated beyond its melting point for proper extrusion.
Since getting the extrusion temperature right is the first step to successfully printing this material, all references to the melting temperature of PLA made throughout this article actually refer to the extrusion temperature of the material.
What Is The Melting Temperature Of PLA?
In 3D printing, it is crucial to make a distinction between melting temperature and extrusion temperature.
The former is the temperature at which the material becomes a liquid. Knowing the melting temperature is important to determine a material’s suitability for a certain application.
For instance, materials with a low melting temperature also have a low glass transition temperature and are unsuitable for outdoor applications.
Items made of PLA are often unsuitable to use in the microwave or oven, where temperatures often exceed the melting point of the material. However, you can wash them in the dishwasher.
As mentioned, PLA has a melting temperature between 150°C and 180°C.
The extrusion temperature of PLA is the temperature at which the printer’s hot end must heat the filament to ensure correct extrusion and avoid issues with layer adhesion or printing defects.
This temperature varies from around 190°C to 220°C, but it can be slightly lower or higher depending on the actual filament you’re using, the extruder type, and even the type of printer.
Factors Affecting PLA Melting Point
PLA’s extrusion temperature is affected by a variety of factors. From the extruder type to the type of build plate and processing conditions during filament production, they all have an impact on the temperature your hot end should have.
So, here’s the PLA melting temperature that you should use based on various factors
One of the most important factors to consider when printing PLA is the type of extruder your printer has.
|Extruder Type||PLA Temperature||Temperature Considerations|
|Direct drive extruder||190°C to 220°C||Direct drive extruders typically work with PLA at lower temperatures, as they push the filament directly into the nozzle. Set your hot end at 190°C to 200°C and gradually increase (around 5°C at a time) to adjust issues like poor layer adhesion or under extrusion.|
|Bowden extruder||200°C to 230°C||Bowden extruders push the molten filament into the nozzle via a flexible plastic tube. The filament slightly cools as it’s being pushed, which is why these extruders require a higher hot end temperature. As with direct drive, start at the lower end and adjust as needed based on the print quality.|
|All-metal hot end||210°C to 240°C||All-metal hot ends are notorious for fast heat dispersion, which is why they typically require a higher temperature for PLA printing. However, you should be careful not to exceed PLA’s maximum temperature limit, as it could lead to material degradation and poor print quality.|
|PTFE hot end||190°C to 220°C||This type of hot end gets its name from the PTFE liner inside the heat break that limits the maximum temperature of the nozzle. To avoid damaging this liner, you should extrude PLA at temperatures similar to those used by direct driver extruders.|
Regardless of the extruder type, it’s essential to perform test prints and adjust the temperature based on the print quality of the specific filament that is used.
Keep in mind that different PLA formulations and additives, such as dyes or fillers, can affect the optimal printing temperature. Consult the manufacturer’s guidelines for the filament you are using and fine-tune the temperature settings as needed.
Beyond the extruder type, another major factor that impacts PLA’s melting temperature is its grade. That’s because different PLA grades have varying molecular weights, and higher molecular weight tends to have a higher melting temperature.
The additives and blends in the various grades also have an impact on the melting point, in addition to the impact generated by the material’s molecular weight.
The table below shows the various temperatures for different PLA grades.
|PLA Grade||Melting Temperature||Considerations|
|Standard||190°C to 220°C||Standard PLA typically contains no additives or enhancers, and most filaments melt at the specified temperatures. However, dyes may affect the melting point.|
|PLA+||205°C to 230°C||An enhanced type of PLA, PLA+ contains additives that improve the material’s mechanical properties, its strength and durability. Those additives increase the melting point.|
|High-temperature PLA||210°C to 240°C||This type of PLA is specifically designed to withstand annealing, which is a post-processing heat treatment. Hence, it has higher extrusion temperatures.|
|PLA composite||190°C to 240°C||Composite is an umbrella term designating various types of PLA. The actual type of composite determines the extrusion temperature, which can be lower or higher. Common PLA composites include wood, metal, and carbon fiber filaments, to name just a few. For the best results, it is essential to follow the manufacturer’s printing guidelines and specific temperature recommendations.|
|Flexible PLA||220°C to 240°C||Also known as soft PLA, this is actually a TPU-PLA blend. The elastomers in TPU give PLA more flexibility and rubber-like properties, making the material suitable for printing phone cases and other types of flexible items. The added elastomers increase the melting point in the same way other additives do.|
Keep in mind that these temperature ranges are general guidelines, and the optimal extrusion temperature for a specific filament may vary.
It’s essential to follow the manufacturer’s recommendations for the PLA filament you are using and adjust the temperature based on test print quality.
Apart from the extruder type and PLA grade, the processing conditions (calibration of the printer and type of bed) can also affect the temperature.
The cooling rate, print speed, and print bed temperature are the three most important factors to check when printing with PLA.
As far as cooling is concerned, you should adjust the fan speed and layer time.
PLA typically benefits from a fan speed of around 50 to 100 percent. Higher fan speeds can help prevent warping and improve surface finish, but they can also cause issues with adhesion and layer bonding.
The layer time setting determines how long each layer is exposed to the cooling fan before the next layer is printed.
A typical layer time for PLA is of around 5-10 seconds. This helps ensure that each layer has time to cool before the next layer is added.
However, instead of setting a generic layer time, smaller prints may benefit from a minimum layer time. This option ensures that each layer has a minimum amount of time to cool before the next layer is added.
In addition to small prints, this setting is optimal for prints that require a high amount of cooling.
As far as the print speed goes, keep in mind that higher print speeds require higher extrusion temperatures to ensure that the plastic is melted and extruded properly.
The room temperature can also affect the way PLA is printed. In a cold environment, you might want to set a higher extrusion temperature to prevent the filament from cooling too quickly.
Impact Of Incorrect PLA Melt Temperature
Printing PLA at an incorrect temperature can lead to various issues affecting the quality, appearance, and mechanical properties of your printed object.
Incorrect temperature can be either too hot or too cold.
1. Stringing and Oozing
Stringing and oozing is one of the most common defects when printing PLA, and are often the result of excessively high hot end temperatures.
When heated too much, the filament becomes too fluid and it will ooze out of the nozzle during non-extrusion movements.
2. Over Extrusion
Higher temperatures can result in over-extrusion, causing blobs, zits, and thick layers that affect the print’s surface finish and dimensional accuracy.
High temperatures can also cause the material to spread out and lose fine details in the printed object.
3. Poor Bridging and Overhangs
When printing at high temperatures, PLA may not cool fast enough to maintain its shape during bridging or overhangs, leading to sagging or drooping.
This issue may be unnoticeable in prints with few overhangs and short bridges. However, it can ruin the entire print in the case of longer bridges or pronounced overhangs.
4. Discoloration or Degradation
Overheating PLA can cause discoloration or degradation of the material, leading to a weaker print with reduced mechanical properties.
5. Under Extrusion
While a too hot nozzle can lead to over-extrusion, printing at too low a temperature can cause the filament not to melt properly. This can cause under-extrusion and gaps in the print.
If the defects are small, you’ll usually be able to fill them with filler during post-processing and sand them to a satisfactory finish. However, if you’re printing functional rather than decorative parts, gaps, and holes could affect the mechanical properties of the print.
This means that you’ll have to start over, losing time, energy, and material.
6. Poor Layer Adhesion
Another problem with insufficient temperature is weak layer bonding. This could cause the printed layers to separate or delaminate easily.
This problem, too, can lead to reduced mechanical strength.
7. Poor Surface Finish
Printing at a low temperature can cause a rough and uneven surface finish on the printed object.
Moreover, if the temperature is too low, the filament may not flow smoothly through the nozzle, causing clogs and jams.
PLA Melting Temperature vs. Extruder Temperature
We already mentioned that the melting temperature and extrusion temperature of PLA are not the same.
The melting temperature of the material is the temperature at which the plastic transitions from its solid form into a liquid one. This transition starts when the plastic reaches its glass transition point, but at glass transition temperature, it is still too viscous.
At melting temperature, the filament is thoroughly molten, but it could still be too viscous to work with.
For this reason, 3D printers have to heat the material at a temperature at least 10°C higher than the melting temperature. This is the extrusion temperature, which for standard PLA varies from about 190°C to 220°C.
To maintain the material at the right printing temperature throughout the entire printing process, you must also consider the bed temperature, print speed, and retraction settings.
The bed temperature, typically around 50°C to 70°C, keeps the extruded material warm enough to ensure proper bonding between layers.
For PLA, the ideal print speed should be 40 to 60 mm/s. A slower speed requires a lower nozzle temperature, which might not melt the material effectively.
To prevent oozing or stringing, you should also set the retraction between 25 to 40 mm/s, based on the actual temperature that you’re using.
PLA’s melting temperature varies from 150°C to 180°C, but the material requires a higher hot end temperature for proper printing. Typically, the nozzle should be heated between 190°C and 220°C to prevent printing defects.
We hope this guide can help you understand the difference between melting and extrusion temperatures, and how to set your printer for the various PLA types.