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02 July 2018 17:48
PLA 3D Printing: All You Need to Know
Polylactic Acid (PLA) ranks as one of the most popular materials for 3D printing, particularly FDM. Its ease of use and minimal warping issues make PLA filaments the perfect starting point for 3D printing. PLA is also one of the most environmentally-friendly 3D printing materials and, unlike ABS, is biodegradable. Among other PLA advantages are also its low cost and a wide assortment of colours and blends. However, the brittleness of the material makes PLA more suitable for non-functional prototyping, decorative and low-stress applications.
In this guide, we’ll be taking a closer look at the benefits and limitations of PLA, as well as optimal printer settings. We’ll also explore common applications of the material and share some tips for getting the most out of 3D printing with the material.
Why 3D print with PLA?
PLA is a common thermoplastic polymer derived from natural sources such as corn starch or sugar cane — in contrast to many other thermoplastics which are produced from non-renewable sources such as petroleum. From automotive to food packaging, a range of industries are using PLA to produce 3D printed products.
Advantages of PLA include:
- Low printing temperature: PLA has a relatively low printing temperature compared to other thermoplastics (e.g. for PLA an ideal printing temperature starts from around 180°C, while ABS this is around 250°C). This means that PLA is less likely to warp and clog the nozzle during the printing process. Also, compared to ABS and other thermoplastics with higher melting temperatures, PLA typically produces better surface details and sharper features.
- Ease of use: PLA is one of the easiest material filaments to 3D print with. The material easily adheres to a variety of surfaces and doesn’t require a heated print bed which, again, adds to its ease of use. Unlike ABS, PLA also does not emit smelly fumes when printed.
- Variety of colour and blending options: PLA is easily pigmented and comes in a diverse range of colours and blends. The material can also be mixed with wood, carbon and even metal, whilst pigments can also be added t to get luminescent or glittery filaments. This makes the choice of PLA blends virtually endless.
- Easy post-processing: PLA prints can be easily sanded, polished and painted, allowing for an improved surface finish with relatively little effort. You can also drill, mill and glue PLA parts — but be careful not to melt the part. To prevent melting your PLA part, simply keep the process slow and the tools cold (you can achieve this with water, WD-40 or proper cutting fluid).
- Biodegradable: PLA is an eco-friendly material, as it’s biodegradable, non-toxic and also requires less energy to 3D print and emits fewer greenhouse gases than petroleum-based materials. Compared to petroleum-based thermoplastics, which take thousands of years to break down, PLA parts can typically (naturally) break down within a few years, or even months.
What are the limitations of 3D printing with PLA?
- PLA has low heat resistance, and therefore cannot be used for high temperature applications. In high temperatures, PLA can rapidly deform, especially if under stress.
- PLA is typically weaker and has a lower tensile strength than its counterparts, ABS and PETG. Since PLA parts, when 3D printed, are quite brittle, the material is more suited to aesthetic rather than mechanical purposes.
- While PLA containers are food safe when not 3D printed, PLA is not food safe when 3D printed. This is because the 3D printing process creates tiny gaps and pores between the layers of your print. These gaps tend to keep moisture and bits of food, leading to a build-up of bacteria and mould.
- When heated, PLA filament is prone to oozing, meaning that your printer’s extruder can leak out a lot of plastic when moving between segments of a print. This creates strings between the separate areas of your part, which can result in a flawed print. A cooling fan is therefore required to prevent this issue.
The material properties of PLA make it more suitable for applications where look and form are more important than strength and durability. Therefore, the best applications for PLA are items designed for decorative rather than “wear and tear” use. PLA filaments are also a good choice for low-cost rapid prototyping, accurate and vivid models, props, pastry moulds, and containers.
In the automotive industry, PLA is frequently used to print tools, jigs and fixtures. However, it’s important to remember that PLA prints can’t withstand high temperatures and are brittle when first printed, so applications should be chosen in view of the capabilities of the material.
As PLA is a user-friendly, economical material, it’s often used in engineering departments and by makers and hobbyists in FabLabs to create visual models of components.
5 Tips for 3D printing with PLA
Although printer settings vary depending on the type and blend of PLA filaments, there are some basic requirements and specifications listed below to ensure a successful printing process:
- PLA melting point: 150-160°C
- PLA printing temperature: 180-230°C
- Heated print bed: optional
- Cooling: part cooling fan is necessary
- Enclosure: not necessary
- Filament storage: airtight container
1. TemperatureThe temperature of your printer’s extruder depends on the diameter of the PLA filament (there are two: 1.75 mm and 2.85 mm) and ranges from 180°C to 230°C. Opt for lower temperatures within this range for filaments with a diameter of 1.75 mm, and higher temperatures for the filaments with a diameter of 2.85 mm. Generally, it’s good practice to start printing at a temperature of about 180°C and then adjust the temperature if necessary.
If the printing temperature is too high, this can lead to oozing of melted PLA, resulting in a poor quality print. This problem can be prevented by either adjusting the temperature or retraction distance by a small margin. Based on the results, adjust your retraction distance by 0.5 mm – 1 mm up or down. It is not recommended to have distances greater than 5 mm, or less than 0.5 mm.
Although the speed of 3D printing with PLA can reach up to 90mm/sec, printing at a lower speed (around 40mm/s) will guarantee higher quality end results.
To achieve high-quality prints, it’s important to ensure a proper cooling process. It’s highly recommended to use a part cooling fan to the maximum power throughout the printing process. However, during the first few layers of the printing process, cooling can actually affect the layer adhesion of your part. For this reason, it is better to turn off your fan in the initial moments of the printing process.
Is your PLA filament brittle? Does it bubble during printing? This is likely because the filament is moist due to improper storage. Like ABS, PLA filaments are hygroscopic, meaning that they attract moisture from the air. Therefore, it’s crucial to ensure that the PLA filament is stored in an airtight container.
To Sum Up
As one of the most trusted 3D printing plastics, PLA rates highly amongst industrial manufacturers and hobbyists alike. It is inexpensive and relatively easy to use, provided that the 3D printer’s settings are properly adjusted. In this regard, we hope that everything mentioned in our guide will help you to succeed when 3D printing with PLA filaments.