In this article, we will be exploring the PLA material. PLA is a widely popular filament for FDM 3D Printing. It is literally considered to be the first material every 3D printer user ever uses. Its bio-degradable nature, wide availability and cheap price offering good mechanical strength make it the obvious choice for many new users. We will explore the material in more depth through this article.
WHAT IS PLA MATERIAL?
Courtesy: Felfil
PLA stands for Poly Lactic Acid which is a thermoplastic polymer i.e., it can be melted to form liquid and cooled to form solid and reheated and this can be carried many times over without any significant degradation in its properties. It has a chemical formula of (C3H4O2)n & is derived from bio-degradable resources like corn starch or sugar cane, unlike most polymers that are obtained from non-renewable petroleum resources.
How long does PLA last?
As a bioplastic, PLA degrades naturally upon exposure to the environment and can degrade anytime within six to 24 months. Such a quick degradation is not seen in any other plastic. This property can be utilized to good effect if it is used in products where periodic degradation is desirable like plastic bottles, use & throw containers, packaging, etc. This is one of the major reasons for PLA materials’ popularity.
Another important reason for the popularity of PLA is the fact that it can be manufactured through existing manufacturing equipment.
It does not require any special set-up and this makes it a cost-efficient material to be produced. It is one of the largest produced bio-degradable polymers ever. And so the world-wide availability at cheap cost with bio-degradable property, make it one of the most desirable materials.
As far as mechanical properties are concerned, PLA is highly stable and can produce repeatable performance over a long duration. It is extremely robust for in-system applications and showcases characteristics similar to polypropylene (PP), polyethylene (PE), or polystyrene (PS).
Some Generic Properties of PLA
Heat Deflection Temperature (HDT): 49 – 52 °C (121 – 126 °F) at 0.46 MPa (66 PSI)
Tensile Strength: PLLA: 61 – 66 MPa (8840 – 9500 PSI)
Flexural Strength: PLLA: 48 – 110 MPa (6,950 – 16,000 PSI)
Specific Gravity: PLLA: 1.24
Shrink Rate: PLLA: 0.37 – 0.41% (0.0037 – 0.0041 in/in)
UNDERSTANDING PLA 3D PRINTING FILAMENT
As explained earlier that PLA is a popular filament for FDM 3D Printing. It offers multiple benefits along including the ease of printing.
PLA filament melts at around 190°C making it suitable even for cheaper brass nozzles to extrude. The material easily sticks to the build plate while 3D printing and also does not warp thus eliminating the need of a heated bed, or an enclosure that adds to the overall cost of the 3D printer.
PLA does not give off a foul odor during printing and in fact many users report smelling a sweet smell while printing with PLA. The material is available in the highest number of colors and blends (composite materials).
Due to easy & cheap availability of the raw materials across the world, PLA is used as a base material for a vast variety of composite materials. PLA-based composites are quite popular and used for aesthetic applications like display prototypes, toys, props, cosplay, etc.
The composites includes materials like wood-filled, metal-filled, glow-in-the-dark filament & even PLA-based PETG & Carbon-Fiber. Such a combination enhances the mechanical properties of PLA and simplifies printing of PETG & Carbon Fiber. We will talk more on these composite blends in the future section.
Making sure your equipment is up to the job of printing PLA:
Not all printers were created equal. Some will be capable of printing these diverse wood or metal blends and others won’t. You should check with the manufacturer online to confirm you’ll be able to handle printing some of these blends. Not all the filaments will be easy to handle so make sure your set up, is up to scratch.
Perhaps you’re not interested in printing these blends yet and are more focused on just printing different color variations of PLA. There are still somethings to keep in mind, your printer still needs to be confirmed as capable and even then, it’s best to print PLA using a printer with a filament fan. PLA is a cold bed filament, after all.
Making sure your equipment is up to the job of printing PLA:
Not all printers were created equal. Some will be capable of printing these diverse wood or metal blends and others won’t. You should check with the manufacturer online to confirm you’ll be able to handle printing some of these blends. Not all the filaments will be easy to handle so make sure your set up, is up to scratch.
Perhaps you’re not interested in printing these blends yet and are more focused on just printing different color variations of PLA. There are still somethings to keep in mind, your printer still needs to be confirmed as capable and even then it’s best to print PLA using a printer with a filament fan. PLA is a cold bed filament, after all.
IS PLA FILAMENT FOOD SAFE?
PLA is considered as a food safe material since it is made from corn starch but according to multiple studies the material gets toxic when it is extruded through the brass nozzle. So, it should not be considered as a food safe material by-default. Instead users should consult their manufacturers before they use PLA 3D printed products for applications that involve contact of food with PLA.
If at all users want to use PLA for printing objects like cookie cutters then a stainless steel nozzle should be used.
3D PRINTING WITH PLA FILAMENT
PLA 3D printing is fairly easy compared to other 3D printing filaments. It also has a higher 3D printing success rate and a print rarely fails. But still users need to learn about the material and how it should be printed.
So, we will suggest the general print settings to get started with the printing process. It should however be noted that not all materials are the same and so the print settings will require certain tweaks every time you change the filament from one brand to the other. The print settings should be in accordance to the settings recommended by the filament manufacturer.
General Printing Settings for PLA Filament
Extruder Temperature: 180 – 200 °C
Bed Temperature: 40 – 60 °C (Optional)
Printing Speed: 30 – 80 mm/s
POPULAR BLENDS OF PLA FILAMENTS
PLA filament is often found in lot of composite materials. The printing ease of PLA filament makes it a perfect base material while formulating composite materials. Below are some of the most common PLA-based composite materials.
Wood-filled PLA Filament
PLA filament is often combined with wood dust, cork or powdered wood derivatives to form wood-filed PLA filament. Typical composition is around 30 – 35% wood and rest as PLA however it may vary according to the manufacturer. Wood filaments are found in numerous variants like birch wood, coconut wood, bamboo, cork wood, etc.
Metal-filled PLA Filament
Similar to wood-filled filament, metal filled filaments are manufactured by mixing metal particles with PLA filament. The composition depends on the properties desirable in the new composite material. Metal filaments are also found in multiple variants like aluminum-filled, brass-filled, copper-filled, etc.
Ceramic-filled PLA Filament
Ceramic powder is mixed with the base PLA filament to create a ceramic-filled material for 3D printing.
Glow-in-the-Dark Filament
This material is formulated by mixing phosphorescent materials in the base PLA filament. Even though it is expensive than regular PLA filaments, they can used to create fun products like toys, glow in the dark glasses, masks, etc.
PLA Carbon Fiber
This filament contains PLA missed with carbon fiber particles. Carbon fiber gives added strength to PLA while PLA helps easy printing of Carbon Fiber. Compared with 100% carbon fiber, this material exhibits lesser strength but is easy to print with.
Other mentionable PLA composites are stone-filled, coffee-filled, beer, color-changing, and silk among many others.
ADVANTAGES OF 3D PRINTING WITH PLA FILAMENT
- Easy to use: This filament is very popular because of how easy it is to use compared to some other products. It’s print temperature is much lower, as it’s a cold bed filament. Meaning, less likely to block the nozzle or warp it. And less expensive to run.
- Bio-degradable: The biggest advantage of PLA is its biodegradable nature. It can naturally degrade in six to 24 months.
- No Warping: PLA does not warp thus reduces chances of print failure due to stringiness, blobbing and warping.
- Wide Availability: PLA is widely available in a vast range of colors and style.
- Cheap Price: It is available all across the world as more-or-less the same cheap price.
- Great Base Material: PLA is a great base material for formulating composite materials. A large variety of composites like wood-filled, metal-filled, glow-in-the-dark, silk, ceramic-filled, etc., use PLA as its base material.
- Smells Sweet: More often than not, PLA printing releases a sweet smell that is pleasing to some users. If you’ve experimented with different filament types you know that some tend to give off a foul odor, when used frequently that can become less than ideal. PLA doesn’t smell bad the same way other types, such as ABS, do.
- Lost PLA-casting: Since PLA exhibits a low melting point, it is also used for lost PLA-casting process where the inner cavity is printed with PLA covered by an outer layer of other material having a higher melting point than PLA. This is then heated to melt the PLA away so that only the outer part remains. The inner cavity can then be filled with molten metal. This process is common in making jewelry.
- User-Friendly: PLA is highly user friendly as it melts at lower temperature, requires modest equipment’s to print (cheap brass nozzle, no need of heated bed, no need of enclosure, etc.) and is easy to print and dispose-off.
DISADVANTAGES OF 3D PRINTING WITH PLA FILAMENT
- Average Mechanical Properties: Compared to other available 3D printing materials, PLA has only average mechanical properties.
- Hygroscopic: Like almost all thermoplastic polymers, PLA also is hygroscopic in nature.
- Low Glass Transition Temperature: This property makes PLA unsuitable for high temperature applications. It is even not suitable for outside applications in tropical regions.
- Brittle: PLA is comparatively more brittle than materials like ABS and that can cause a problem in some applications. It also means it should be avoided for use around food or produce as it’s brittle nature leaves it absolutely not food safe.
- Creep: Overtime PLA exhibits a phenomenon called as creep. It literally means that over longer durations PLA starts to lose its shape and its mechanical properties also change so it will not be useful.
- Cold bed filament: Although being cold bed was given as a positive multiple times above, it does have some drawbacks because it reacts poorly to heat. This means when direct heat is applied it can warp and distort permanently damaging it.
- PLA has a short lifespan: The cost of being environmentally conscious is a short life on your prints. Because PLA is designed to only last 6 -24 months, this should be considered when using it, instead of a longer lasting more sturdy filament. This isn’t a problem if you aren’t expecting your prints to last this long anyway, but it is something to be considered.
Is PLA plus worth the money?
The answer is it honestly depends on what you’re looking for. Some companies will dishonestly label their filament as “pro” or “plus” to try to increase sales. It can be difficult to determine whether this more expensive filament you’ve got your eye on is actually worth the money or if it’s just advertisers waffling.
Normally it’s best to stick to the most popular brands and check out some reviews online first. It’s better to pay more for a well known brand “better quality” product than for a no name one that’s half the price. It’ll end up costing more if you damage the printer with shoddy filament.
What should and shouldn’t PLA be used for:
The pros and cons of PLA above give a good indication of what it should and should not be used for. Here is a more comprehensive list of PLA’s best applications.
PLA should be used for making prototypes:
It’s quick and easy printing means PLA is a great choice for creating a prototype product that’s not expected to actually fulfil the need of the finished thing.
Should be used for creating visual products:
PLA’s diverse colors and blends means it’s a great choice of filament for creating art, cool prints and general aesthetic items that aren’t meant to actually perform a function except look good.
PLA should not be used for machinery:
PLA is absolutely not designed to be part of any machinery, it doesn’t have the structural integrity that one might hope for. Nor does it have the heat resistance needed for being part of a machine. If you’re looking to 3D print some spare parts PLA is not the filament for you.
PLA should also not be used for anything that is expected to bend, it’s incredibly brittle and will just snap instead.
Does PLA have high toxicity?
PLA, unlike many other filaments, actually has a low toxicity. That’s one of the reasons it’s so popular. It’s a great alternative to other more common filaments that can be extremely harmful.
Now, this doesn’t mean that it’s toxicity free. Unlike some filaments that emit carcinogens, PLA emits something called ”lactide”. Lactide is actually thought by some researchers to be completely harmless; though there hasn’t yet been enough research so you should still be careful. Try to avoid inhaling the fumes.
How should I store my PLA?
Like many filaments PLA needs to be stored safely and carefully. If left out it can absorb moisture from the air and it’ll completely ruin the filament. Special storage containers can be purchased that hold multiple spools, so you can keep all your favorite colors.
How much does it cost and where can I buy it?
PLA is one of, if not the most, readily available filament types. You should be able to find it almost anywhere that sells 3D printing equipment. Because of how popular and common it’s become you can find and purchase 1KG of PLA for about US$25.
Verdict
PLA is a very popular material for all beginners and even for professionals. Beginners enjoy it for the easy of printing and cheap availability. PLA also offers limitless colors and unique blends like metal-fill, glow-in-the-dark and more.
Professionals like the material as it is a great prototyping material. With a PLA Carbon-fiber composite, they can enjoy the ease of printing with carbon fiber with the worry of frequent print failures.
So, it is safe to say that though PLA is consumed a lot by a beginners, it is also used by professionals for specific applications. Not sure if PLA is the right filament for your project, take a look at other filaments and learn which is best for your project.