Types of Plastic
You may not realize it, but you’re very familiar with ABS even if you don’t own a 3D printer. ABS is the same plastic used by LEGO for their bricks.
Nowadays ABS is one of the more popular materials to print with, probably because it was the pioneer material used for 3D printing. However, it ha s some intrinsic shortcomings that can disappoint the inexperienced user. ABS has a glass transition temperature – the temperature at which the polymer softens – of about 105˚C and the printing temperature usually varies between 230˚C and 260˚C. ABS has the tendency to shrink when it cools down and can lead to deformation (warping) and delamination (cracking) of your print. Warping occurs at the bottom of a 3D printed object and a heated bed can be used to prevent this.
Delamination can occur at higher parts of your 3D print and is more difficult to avoid. The use of an enclosed frame or a work-around to keep the flow of air out and the heat in, could help to prevent these undesired effects caused by shrinkage.
CPE and ABS are usually printed with lower speeds because of the maximum temperature of the printer (Remember my previous post? When increasing speed you must also increase temperature). The fans mounted on the side of your Ultimaker make 3D printing overhangs and small details possible, but this can worsen layer bonding. Thicker layers and bigger nozzle sizes usually create stronger objects!
Deciding on what is the best temperature for your ABS print requires a more careful approach than with PLA. The temperature range over which PLA changes from a liquid to the point where it carbonizes is much larger than ABS. So for most people this means PLA is more user friendly as the exact printing temperature you choose is less crucial. This also means you have some more room to play with printing speeds and temperatures.
Much like a regular 2D inkjet printer a 3D printer can generate fumes when heating materials up. These fumes are not by definition harmful, but they could be a concern when printing above the maximum temperatures advised on the Material Safety Data Sheets by suppliers. Therefore, printing ABS must be done in a well-ventilated area and preferably with an additional extraction system (for example, you could use a kitchen extractor hood). In contrast to ABS, PLA is currently not known to be hazardous.
PLA AND ABS ARE JUST THE START
Many users have started their journey into 3D printing making lots of Yoda heads, vases, gadgets, busts and other fun prints – mostly with PLA. But at some point they get more familiar with the idea of owning a 3D printer and then they start seeing the huge potential in applying it to daily life. They’ll start to move onto more functional items, perhaps repairing things around the house, upgrading tools, etc. But will PLA still do the trick? Or do you need another material with different properties? A tougher material with a higher temperature resistance? And should these be biodegradable?
PLA: PLA is used for its nice finish, easy and fast printing characteristics and for the large amounts of colours and varieties available. PLA is usually not as durable compared to the alternative materials. Some PLA can be smoothened using chloroform.
ABS: ABS can be used for mechanical parts which need to keep their strength at higher temperatures and keep their rigidity. ABS isn’t designed to be flexible, which is a benefit. ABS is more matte in appearance than other materials but it can become very shiny after acetone vapour smoothing, so it’s not just for mechanical parts. However, ABS has poor chemical resistance, while CPE and XT have excellent chemical resistance, which is why ABS can be made smoother by acetone vapour. Acetone is safer – although very flammable – than the chloroform which can sometimes be used to smoothen PLA.
CPE: CPE is easier to print than ABS and is very strong. It can be used for mechanical parts that do not heat up and for parts that could benefit from some flexibility. In contrary to ABS it can bend a little bit. It’s safer in terms of fumes and particle emissions while printing. It’s also chemical resistant and is said to be water-tight. CPE can’t be made smoother using chemical vapours. Transparant prints are also possible using the natural color of CPE. Using thick layers and a wider thread than your actual nozzle size (like 0.5mm extrusion with a 0.4mm nozzle) will benefit the transparency.