How PLA Melting Point Influences 3D Printing

Widely used for prototyping and to produce visual models, PLA (polylactic acid) is one of the most common 3D printing thermoplastics in use today. And for good reason: the filament is both easy to print and affordable. However, in order to unlock the most benefits from PLA when 3D printing, it is important to know the material’s properties, like what is the PLA melting point. 

Having a grasp of the material’s behavior under different temperatures is crucial for achieving optimal printing results. This knowledge allows users to fine-tune their printer settings, troubleshoot issues, and ultimately produce high-quality prints with PLA. In this article, we’ll be going over the properties of PLA, including its melting point and temperature properties, as well as how they influence print settings and best practices.

The Basics of PLA

Before we dive in, let’s first look at PLA in more depth. Also known as polylactic acid, PLA is a biodegradable thermoplastic polymer derived from renewable resources like cornstarch, sugarcane, or tapioca root. As a raw material, PLA has become popular in various industries due to its low environmental impact and ease of processing, including in the world of 3D printing. In fact, PLA is one of the most widely used polymers for 3D printing applications. 

PLA’s popularity can largely be attributed to its low cost, ease of use, and good print quality. It is considered one of the most beginner-friendly materials for 3D printing, as it requires relatively low printing temperatures and displays minimal warping during the printing process. PLA is also known for properties such as good stiffness and tensile strength, low thermal expansion (minimal shrinking as it cools), and a pleasant semi-sweet smell when printing. Additionally, PLA's availability in a wide range of colors adds to its appeal for both hobbyists and professionals alike.

PLA is a popular material due to its cost, ease of printing, and wide variety of color options.

As a thermoplastic material, PLA starts to soften and eventually melts when heated. And as the material cools, it starts to resolidify.[1] This means that thermoplastics like PLA can be processed and reprocessed, facilitating recycling and reuse. It also enables the material to be processed using methods like 3D printing and injection molding.

One thing to note about PLA is that the material is not particularly well suited to outdoor applications due to its sensitivity to environmental factors. PLA tends to degrade when exposed to UV light, heat, and moisture. Outdoor conditions can therefore cause PLA to warp, become brittle, or lose strength over time.

The Science Behind PLA’s Melting Point

A material’s melting point is a critical property in material science, as it represents the temperature at which a solid material transitions into a liquid state. 

Several factors determine a material’s melting point, including its molecular weight and crystallinity. For instance, PLA is a semicrystalline polyester that consists of chains of lactic acid molecules, and its melting point is influenced by the molecular weight of these chains. The molecular weight represents the mass of a single molecule (measured by adding up the weight of each atom in the molecule), and a higher molecular weight generally corresponds to a higher melting point. 

PLA's melting point typically ranges between 150°C and 180°C, although this varies depending on the specific grade of PLA and whether the material has any additives. Manufacturers often incorporate additives into thermoplastics, such as pigments, plasticizers, or stabilizers, to modify the material's properties, including its melting point. These additives can either increase or decrease the melting point of PLA, depending on their specific characteristics and concentrations.

How to Measure Melting Point

In materials science, the melting point of PLA (and its glass transition) is commonly determined by Differential Scanning Calorimetry (DSC).[2] In a DSC test, a small PLA sample is gradually heated and the heat flow is measured. The DSC thermogram will show an endothermic peak when PLA’s crystalline regions melt, this peak typically appears around 150–170 °C for PLA.

A DSC is a precise method to identify the melting point in a lab. For practical 3D printing purposes, however, users often determine the appropriate melting/printing temperature by empirical testing (like a temperature tower) since filament formulation differences mean the ideal extrusion temperature might be a bit above the raw polymer’s melt point.

To create a temperature tower, design a model with varying print temperatures at different height segments. Start with a lower temperature at the base, gradually increasing the temperature as you go up. This helps assess material performance across different temperatures to find the optimal one. In fact, you don’t actually need to design your own temperature tower, as slicer programs like Cura have plug-ins, like the AutoTowers Generator, that will do it automatically.[4]

PLA's melting point can vary depending on the grade of plastic and additives present in the material.

PLA Melting Point in 3D Printing

When it comes to 3D printing, a material’s melting point—as well as other material properties—determines the temperature settings users should apply both for the print head and heated bed, as well as the cooling mechanisms needed to prevent warping and ensure optimal print quality. 

Temperature Settings 

PLA filament starts to soften at about 60°C (its glass transition temperature) and has a melting point between 150°C and 180°C, depending on the specific material formulation. Most PLA filament brands recommend 3D printing at a temperature slightly higher than this, between 180°C and 220°C. We recommend starting with the manufacturer's recommended temperature settings and fine-tune as necessary based on print quality.

Bed temperature is another setting to consider. Generally, PLA does not require a heated bed (the material demonstrates good first layer and interlayer adhesion at room temperature), however it can benefit from a bed temperature between 40°C and 60°C. A heated bed is especially useful when printing larger parts (to stabilize the cooling rate) or when printing in a colder environment. 

One thing to note is that enclosures or heated chambers are not needed for PLA. In fact, a heated enclosure can be counterproductive: if the environment around the print stays too hot (near or above PLA’s glass transition temperature), the layers may remain soft and the print can deform or slump. Many makers actually print PLA with the printer’s enclosure open or with active cooling to keep the print environment near room temperature. PLA’s low warpage means it tolerates normal ambient conditions well (20–30 °C air), unlike ABS which can benefit from an enclosure. 

Cooling Settings

Cooling also influences the success of a 3D print: if a part cools too quickly it can be prone to more shrinkage, and if it cools too slowly it can result in deformations, like sagging. Active cooling fans, which help dissipate heat and maintain consistent temperatures across the printed layers, can be beneficial when 3D printing with PLA. 

It is common when using a cooling fan in the 3D printing process for it to initiate after the first couple of layers have been deposited. This is to promote strong adhesion between the first layers and the print surface. Once the first layers have a strong bond with the bed, the cooling fan can be brought up to 100% for the duration of the print. Consistent cooling ensures that each layer of PLA has hardened sufficiently before more layers are applied. 

Recommended reading: PLA bed temperature & print temperature settings

Importance of Using the Right PLA Print Settings

As with any thermoplastic, PLA’s material properties, such as melting point, should be taken into consideration when preparing a print job. In other words, choosing the right combination of print settings has a big influence on your print results, including the following:

• Layer Adhesion: Layer adhesion refers to the bonding between every extruded layer of melted plastic. As the thermoplastic solidifies upon cooling, the bonds between layers should be strong. Proper layer adhesion is crucial for producing strong, durable prints with minimal risk of delamination or other structural defects, and temperature settings—including print and bed temperatures, as well as cooling—play a big role. Typically, if the print temperature is too low, it can lead to poor layer adhesion.

• Print Quality: With the right temperature settings, PLA will flow smoothly through the extruder and form consistent, even layers as it is deposited. Printing at temperatures below PLA’s melting point can result in incomplete melting, leading to filament jams and other issues like bad adhesion. Conversely, printing at temperatures too far above the melting point can cause excessive material flow, leading to over-extrusion, oozing, and poor print quality. 

• Material Compatibility: PLA's melting temperature is also an essential consideration when using it in combination with other materials, such as in multi-material prints or support structures. It is important to ensure that the melting points of both materials are compatible to achieve successful printing and prevent issues such as warping or poor layer adhesion.

Printing Temperatures for PLA Filament Brands

To understand how printing temperature recommendations can vary across different types of PLA filament, we’ve put together a table with a selection of popular PLA filament products and the supplier’s suggestions for print settings:

Troubleshooting PLA 3D Printing Issues

When encountering issues when 3D printing PLA, it is important to identify the root cause and implement appropriate solutions. This section will explore troubleshooting techniques to address common temperature-related problems that can impact print quality and success.

Issues like oozing and under-extrusion can usually be fixed by decreasing or increasing the print temperature.

Common PLA Melting Point Problems in 3D Printing

• Oozing: If you notice any oozing or blobs in your printed parts, it’s time to take a look at your print temperature settings. This 3D printing issue is typically caused by too high a print temperature, so if you spot this issue, try lowering the hot end temperature by a few degrees at a time until the oozing stops.

• Stringing: Stringing can also occur if the PLA filament's melting point is too high, causing the material to flow more freely than intended. Lowering the extruder temperature can help prevent this issue and ensure cleaner prints.

• Under-extrusion: Under-extrusion, which can lead to poor adhesion and structural problems, can be a symptom of printing at too low a temperature. If you notice thin or missing layers, try increasing the print temperature gradually.

• Poor first layer adhesion: If you notice your PLA print is peeling up from the print bed, it could be a sign that the first layers are cooling too quickly. If this happens, we recommend using a heated print bed. PLA prints best with a heated bed around 50°C. If your 3D printer doesn’t have a heated ben, you can always opt for a bed adhesive, like kapton tape or glue sticks.

• Clogged nozzle: A clogged nozzle can occur if the PLA filament's melting point is too low, preventing proper extrusion. Increasing the extruder temperature can help resolve this issue and improve print quality. At the same time, if the printing temperature is too high, it can cause the material to stick inside the nozzle and burn, which can also lead to clogs.

• Warping: Though warping is not as common with PLA as ABS and other high-temperature materials, it can still happen, particularly with larger prints. The cause of warping is related to temperature. Specifically, if the print cools too quickly, it can shrink and pull up from the print bed.Ensure bed adhesion is good (clean surface, proper first layer). To deal with warping, you can use a brim to increase the surface area of the print, or incrementally increase the bed temperature, as this can keep the base warmer a bit longer to prevent early shrinkage. Turning off the cooling fan for the first few layers of a print can also help solve PLA warping.

How Filament Quality Factors In

While all PLA filaments share many properties, filaments do vary in terms of quality and printability. It can therefore be useful to assess the quality of your filament to understand whether it’s the source of any problems. Let’s take a look.

High-quality PLA filaments generally have a more consistent melting point, which can improve print quality and reduce the likelihood of extrusion issues. Poor quality filaments, on the other hand, are characterized by inconsistent filament diameter and can lead to uneven melting and extrusion. To determine a filament’s quality, you can simply measure the diameter of the filament at several points using calipers. 

PLA filament is also very hygroscopic, meaning that it absorbs moisture from the environment. If you print using “wet” filament, the moisture trapped inside the thermoplastic will evaporate when the material is heated, causing air bubbles within the material. Ultimately, this can lead to problems like stringing and blobbling. It’s therefore advisable to keep PLA dry by storing it in airtight containers with a desiccant or by drying it out before using it.

We should also point out that many PLA filaments contain additives such as colorants or performance-enhancing materials, which can impact the material’s melting point. Ensure that the filament's melting point is compatible with your printer's temperature settings.

Recommended reading: How to Dry Filament

Addressing Cooling Issues

For PLA, the cooling fan is your friend. As noted, keep it off or low for the first layers to avoid chilling the print too early (which could lead to poor bed adhesion). After that first layers are down, ramp the fan to 100% for the rest of the print. This ensures each new layer solidifies quickly, supporting the next layer without sagging. Unfortunately, inadequate cooling can lead to problems during the printing process, such as deformations and sagging. Assess the cooling system and settings to identify and resolve any problems:

• Cooling Fan Functionality: Check that the cooling fans are operating properly and providing sufficient airflow to maintain consistent layer temperatures.

• Layer Cooling Time: Adjust the layer cooling time settings to ensure adequate cooling between layers, which can help prevent warping and improve print quality.

A heated print bed is optional when 3D printing PLA, but can help with first layer adhesion

Maintaining Printer Hardware

Regular printer maintenance is also an important part of troubleshooting and ensuring optimal 3D printing performance. For the best results printing PLA, follow these maintenance tips:

• Nozzle Cleaning: Regularly clean the extruder nozzle to prevent clogs and ensure consistent filament flow. Use a nozzle cleaning kit, cleaning filament, or appropriate tools to remove any filament debris.

• Thermistor Calibration: Periodically calibrate the thermistor on your 3D printer to ensure accurate temperature readings. This can help maintain proper extruder and heated bed temperatures, leading to improved print quality and reduced PLA melting point issues.

By following these solutions and best practices, you can effectively address temperature-related 3D printing problems that may occur when printing PLA, resulting in higher-quality prints and a more successful 3D printing experience.

Other 3D Printing Material Alternatives

While PLA is a popular choice for 3D printing due to its low melting point and good printability, there are many FDM 3D printing materials worth exploring that offer different properties and benefits. This section will discuss the melting points of alternative materials and their advantages and disadvantages compared to PLA.

ABS (Acrylonitrile Butadiene Styrene)

ABS is a thermoplastic that has a higher printing temperature than PLA, typically ranging between 220 and 250°C. Interestingly, ABS does not have a melting point due to its amorphous nature.[3] This material is known for its durability, impact resistance, and heat resistance, making it suitable for applications requiring mechanical stability. Compared to PLA, ABS is more prone to warping and requires a heated bed and enclosed print chamber to maintain consistent printing conditions. Additionally, ABS emits fumes during the printing process, necessitating proper ventilation.

Recommended reading: ABS print temperature considerations: Nozzle, bed, enclosure

PETG (Polyethylene Terephthalate Glycol)

PETG has a relatively high melting point around 260°C and prints best at a temperature range between 220°C and 260°C. This material is known for its good printability, durability, and resistance to warping, making it suitable for a variety of applications, including prototyping and functional parts. PETG has better adhesion (and less warping) compared to ABS and does not require an enclosed print chamber. However, it may be more challenging to print with than PLA due to its increased stringing and oozing tendencies.

Recommended reading: How PETG melting point influences 3D printing

Nylon (Polyamide)

Nylon is a high-performance material with a print temperature ranging from 220°C to 265°C. It offers excellent strength, durability, and flexibility, making it suitable for heavy-duty applications and parts requiring good fatigue resistance. Nylon is also highly hygroscopic, meaning it readily absorbs moisture from the air, which can affect print quality. It requires proper storage and drying before use. Moreover, nylon tends to be more challenging to print with than PLA due to its increased tendency to warp and requires a heated bed (between 70-90°C) and, in some cases, an enclosed print chamber.

ASA (Acrylonitrile Styrene Acrylate)

ASA is a thermoplastic similar to ABS but with a higher resistance to UV radiation and weathering. Its ideal printing temperature is in the range of 220°C to 250°C. ASA is suitable for outdoor applications and parts exposed to the elements, as it maintains its mechanical properties and color under prolonged UV exposure. Like ABS, ASA requires a heated bed and an enclosed print chamber to minimize warping, and proper ventilation is necessary due to emitted fumes during printing.

Conclusion

Understanding PLA’s melting point is essential for choosing the print 3D printing parameters and ultimately achieving the best print quality and avoiding potential issues. By optimizing print temperature, troubleshooting common problems, and implementing best practices, users can effectively manage the melting point and enhance the performance of their prints. Furthermore, being aware of alternative materials and their respective melting points enables informed decisions when selecting materials for specific applications.

Frequently Asked Questions (FAQs)

Q: What is the typical melting point range for PLA in 3D printing?

A: The melting point range for PLA typically lies between 170°C and 180°C. However, this range may vary depending on the specific formulation of the PLA filament, additives, and colorants used.

Q: How can I determine the optimal print temperature for my PLA filament?

A: To determine the optimal print temperature for your PLA filament, start by referring to the manufacturer's recommended temperature range. Perform a temperature tower test by printing a test model that varies the nozzle temperature in increments. Analyze the results to determine which temperature provides the best print quality and strength.

Q: Why is my PLA filament not melting or extruding properly?

A: If your PLA filament is not melting or extruding properly, it could be due to an incorrect temperature setting, a clogged nozzle, or a problem with the filament itself. Check the temperature setting, ensure the nozzle is clean, and verify the quality of the filament. If necessary, try a different spool of filament to determine if the issue is material-related.

Q: How to tell if I’m using incorrect temperature settings when 3D printing PLA?

A: Some common signs that your PLA print temperature is not optimized include poor layer adhesion, stringing, oozing, excessive warping, or weak and brittle prints. Adjusting the temperature setting and implementing best practices can help resolve these issues and improve print quality.

Q: Can I use PLA outside?

A: PLA can be used outside for short-term applications, but it's not ideal for prolonged exposure to sunlight, heat, or moisture. Over time, UV rays and weather can cause PLA to degrade, warp, or become brittle. For better durability, consider using materials like PETG, ABS, or ASA for outdoor use.

Q: Can PLA melt in the sun?

A: PLA can soften and deform in high heat, especially in direct sunlight. Due to PLA’s relatively low melting point, prolonged exposure to the sun, especially in hot climates, can cause it to warp or lose its shape.

Resources

[1] The Polymers [Internet]. Britannica. Accessible from: https://www.britannica.com/science/plastic/The-polymers 

[2] Slough, Gray. What is Differential Scanning Calorimetry? [Internet]. TA Instruments. February 7, 2022. Accessible from:   https://www.tainstruments.com/what-is-differential-scanning-calorimetry/ 

[3] ABS Material Datasheet [Internet]. LORRIC. 2023. Accessible from:

https://www.lorric.com/en/WhyLORRIC/Material/material-chemical-resistance-chart-ABS 

[4] AutoTowers Generator [Internet]. UltiMaker Marketplace, 2024. Available from: https://marketplace.ultimaker.com/app/cura/plugins/Kartchnb/AutoTowersGenerator