So you’re new to 3D printing? You’ve done your first few prints, are fully stocked with STL files from thingiverse and myminifactory and now it’s time to purchase some new 3D printing filament. But with all the 3D printing filament types and brands this can seem a bit overwhelming for someone new to 3D printing. When it comes to selecting the right filament there are a few questions you need to ask yourself before spending you hard earned cash.
1. What do I want to print? The items you want to print play the most important role in the filament material to select. A part intended to be used inside a car will require a different material then one used exclusively indoors in a climate controlled environment. The big factor here is what mechanical engineers call the glass transition temperature. Roughly speaking, the glass transition temperature is the temperature at which the polymer material gets soft and pliable like rubber. For example, PLA has a glass transition temperature so low if the part is left in the car on a hot summer day, PLA will soften and permanently deform. MDG Pro Tip: Pay attention to the temperature your prints will be exposed to.
2. Who is manufacturing the filament? Pay close attention to the company who is manufacturing the filament and where it is manufactured. Filament from one manufacture may print much easier and lead to higher quality prints then the same material from another manufacture. This is one of those areas where searching for the absolute lowest cost filament can haunt you with a plague of failed prints. Find what manufacture works for you and stick with it. MDG Pro Tip: In our viewpoint, 3DXTECH is the best filament out there. We like is so much it’s the only filament manufacture we use.
3. Do I need an enclosure to print this material?
A lot of people new to 3D printing are initially attracted to ABS for the high temperature resistance. ABS is a great material, but has a couple challenges that need to be overcome to be successful and safe. First, it puts off toxic Styrene fumes that are harmful to your health enough to cause physical symptoms such as a headache, drowsiness, and feelings of fatigue. ABS should not be printed without an enclosure with an activated carbon filter. Even then, it’s best to keep ABS prints outside the house and in a well ventilated area. Second, ABS suffers a high degree of shrinkage so the entire enclosure needs to be heated to keep the part at an elevated temperature. Without a heated enclosure ABS will warp and print layers will curl away from each other and the print surface. ASA is another great material but has very similar challenges as ABS with high amount of vapors and warp. MDG Pro Tip: As a beginner, avoid materials that require an enclosure until you have mastered the basics of 3D printing with filament materials that are easy to print. Trying to learn the basics while dealing while dealing with a challenging material is a recipe for frustration.
With those 3 questions out of the way let’s get right into the top 5 filament materials if you’re new to 3D printing.
PLA (Polylactic Acid) is the perfect 3D printer filament material to learn the basics on. It’s easy to print and sticks to most bed surfaces without issue. When you’re new to 3D printing stick with PLA for a while before venturing into other materials. Focus on learning the fundamentals of 3D printing such as bed leveling, bed surface preparation, print speeds, extruder calibration, and proper slicer configuration. This is also the perfect time to perform calibration prints to dial in specific performance attributes such as dimensional accuracy, overhang, bridging, retraction, and squareness.
PLA does have some major downsides which are low creep resistance and a low glass transition temperature. Creep is the engineering term for quantifying a materials ability to hold a load over a period of time at elevated temperature. Low creep resistance means a small force and low temperature will cause the material permanently change shape (deform) over time. For PLA, it is subject to engineering creep failure at room temperature. A low glass transition temperature means the material will become rubbery at elevated temperatures and permanently loose form / shape once it returns to normal temperature. For PLA the glass transition temperature is very low at around 50°C.
S. Farah, et al., Physical and mechanical properties of PLA, and their functions in widespread applications — A comprehensive review, Adv. Drug Deliv. Rev. (2016), http://dx.doi.org/10.1016/j.addr.2016.06.012
PETG (Polyethylene Terephthalate Glycol-Modified) is the natural next step once you have mastered PLA, but it is not without some new challenges. PETG will be much more sensitive to a dirty nozzle as PETG tends to stick to itself better then it sticks to the print surface. This means it can lift off the bed if it comes into contact with a dirty nozzle. When this happens, new material exiting the extruder just collects into a PETG ball until it either falls off or swells to engulf your entire hotend.
PETG is more sensitive to a non-level bed. If the nozzle gets too far away from the print surface at any point it simply won’t stick and you find yourself with another PETG ball growing at the end of your nozzle if it happens in the first layer. Get your bed level dialed in by using a bed level calibration test similar to this one. Be sure you can repeatably pass the bed leveling test prior to starting any prints in PETG. This is where a bed leveling probe such as a BL Touch can prove invaluable.
There will be a point with PETG where you get through the first layer, but then notice it is warping off the bed surface half way through. There is no sense in trying to “push through” as this warp will only get worse until the entire part peels off. This occurs because the cooling of each new layer causes further warp. If you see the part curling off the bed, just cancel the print immediately to save filament, and troubleshoot the issue. Most of the time this is a bed leveling, bed adhesion, or print / bed temperature issue. PVA-gule stick can be helpful for PETG and you may want to try a higher temperature for the first layer. At MDG, we like to print 3DXTECH PETG with the first layer at 255-260°C and the remaining layers at 250°C. Printing the first layer slower can also help here, but be careful as too slow can also be a problem particularly if you’re using a low quality PETG and there is a lot of oozing. So you’ll want to go as fast as you can without causing issues. We found a good starting point is 15-20 mm/sec for the first layer.
Once you get the above mastered, you’ll start to be successful with PETG. It’s important know that even when you are getting good prints with PETG you will still have a failed print from time to time. In those instances, just stop the print quickly, troubleshoot and try again.
PETG has a high degree of ductility (low stiffness) and toughness. As such PETG is not well suited for applications that require stiffness such as drone frame components. They will simply flex too much.
Polymers 2019, 11(7), 1220; https://doi.org/10.3390/polym11071220
PLA+CF is a great material to print and has 15% high-modulus carbon fiber compounded in the filament. This is great when you need lightweight structural components with high stiffness. PLA+CF parts also tend to have a high aesthetic appeal and have noticeable carbon fiber sheen. PLA+CF is great for applications that require high stiffness such as drone frame components. Just be careful not respect temperature limits of PLA.
PLA+CF is also a great first material to learn printing with fiber reinforcements. Any fiber reinforcement, such as carbon fiber, will require a hardened nozzle as the carbon fiber is abrasive and will erode a brass nozzle. Carbon fiber is so abrasive it will destroy a brass nozzle in minutes, so don’t even attempt is until you have a nozzle appropriate for the material. As MDG we use A2 tool steel nozzles for any PLA+CF prints.
Also note carbon fiber is black, so this is the only color carbon fiber filled materials come in.
PETG+CF is an excellent material as it improves upon the main weakness of unfilled PETG which is low stiffness. In many ways it is also much easier to print then unfilled PETG. PETG+CF makes for a great choice for general purpose applications requiring occasional outdoor use with increased stiffness. Inside the vehicle parts are also a great application of PETG+CF as it will retain its form under elevated temperatures. If you have a large build volume printer, PETG+CF can be a good choice for vehicle components such as custom airflow management for aftercoolers and other items away from the engine.
At MDG we use PETG+CF for for light duty clamps, fixtures, and alignment tools.
When it comes to Nylon+CF you’re jumping into engineering grade polymers and exiting the world of commodity / general purpose polymers. For more details on this go to our knowledge center page polymer fundamentals. When it comes to nylon , it represents a great deal of the polymers used in everyday products. Take a look at any product around your desk, if it has polymer components they are likely made of Nylon. This is due to the fact that it has high toughness, easily moldable and colorable, good temperature and chemical resistance as well as a low cost.
When it comes to 3D printing Nylon can be a bit challenging and is mainly due to the fact it is highly hydroscopic (absorbs water from air moisture). Nylon filament must be oven dried for 12-14 hours prior to 3D printing and maintained in a heated chamber while the 3D print is in progress. If this is not managed properly, the moisture will boil off and “pop” as the polymer exits the extruder. Simply put, 3D printing wet nylon leads to horrendous print quality. However, since Nylon has such desirable properties for functional parts, companies are beginning to come out with off the shelf filament heating solutions to make this process a bit more manageable.
Before you go diving head first into Nylon+CF, make sure you have mastered PLA, PLA+CF, PETG and PETG+CF. There is a good chance PETG+CF will be good enough for everything you need. In the case it’s not, Nylon+CF is the next material to master. 3D prints from Nylon+CF in many applications are suitable end-use functional parts being strong, stiff, good thermal resistance and have a long service life.