Selecting 3D Printer Filament - Kitronik University
What is 3D printer filament?
Extrusion style printers work by building up thin layers of heated plastic material. This process is known a ‘Fused Filament Fabrication’. The plastic material is supplied on reels and is known as ‘filament’. The filaments looks a bit like wire (without the metal core) and are available in different diameters depending upon the requirement of the 3D printer for which they have been produced.
The plastics used to create the filaments are thermoplastics, which are plastic materials that can be formed into a new shape when heated above a ‘glass transition temperature’ (the point at which the plastic becomes soft and can be reshaped). The two most popular filaments used in 3D printing are ABS and PLA.
Not all thermoplastics are suitable to create filaments for 3D printer. This is because for a material to be used in 3D printing it has to achieve the right balance of:
- A suitable glass transition temperature.
- The right viscosity when heated (not too liquid).
- Good bonding between filament layers.
- Low levels of shrinkage during cooling.
- Suitable mechanical and visual characteristics of the final 3D printed object.
What is ABS 3D printing filament?
ABS stands for Acrylonitrile Butadiene Styrene (ABS is a petroleum derived product). It is a commonly used thermoplastic material and is very popular for 3D printing. ABS has a glass transition temperature (the temperature at which the material becomes soft) of around 105°C.
A typical nozzle temperature for ABS would be in the range of 210°C to 240°C.
Benefits of ABS:
- Strong and quite flexible which makes it a good choice for parts that have a ‘mechanical’ function. Parts are often suitable for post print re-work and machining.
- Good surface quality.
- Nice to touch and feel.
- Good chemical resistance.
- Excellent extrusion characteristics.
Problems with ABS:
- Warping. This is the main issue with ABS. When ABS cools it has a tendency to shrink. This can lead to warping and the material lifting from the print be. For this reason it is essential to use a 3D printer that has a heated bed when printing with ABS, as this reduces the rate at which the ABS cools and keeps any warping to a minimum.
- Smell during the print process. Some people seem to hardly notice this, but to other people it can be more obvious.
- Derived from Petroleum which is a non-renewable source.
What is PLA 3D printing filament?
PLA stands for Polylactic Acid and it is derived from renewable sources such as corn starch. It is a commonly used biodegradable thermoplastic material and is very popular for 3D printing. It is often considered a ‘greener’ alternative to ABS. PLA has a glass transition temperature of around 60°C to 65°C.
A typical nozzle temperature for ABS would be in the range of 180°C to 210°C.
Benefits of PLA:
- Biodegradable and derived from a renewable source.
- More rigid.
- Excellent print layer bonding.
- Low odour during the print process.
- Low warping and can achieve sharp corners and fine detailed prints.
- Glossy feel to prints.
Problems with PLA:
- Low glass transition temperature can cause parts to deform in hot environments.
- 3D printed parts can be brittle and break when over flexed so less suitable to mechanical applications than ABS.
What other 3D printer filaments options are there and what are their characteristics?
Water soluble PVA (Polyvinyl Acetate):
- Used to print ‘support’ material (structures) in 3D printers that can support more than one filament.
- The support material would sit under sharp overhangs and around free hanging components that otherwise sit in free space and would be impossible to print.
- The PVA is then washed away on water to leave the remaining structure.
HIPs (High Impact Polystyrene) - Dissolvable
- Like water soluble PVA HIPs can be used to print support material / structures.
- HIPs can be dissolved in a chemical called Limonene.
- Produces very strong 3D printed objects.
- Has a high glass transition temperature and can require a print head temperature of 250°C or higher.
- Highly transparent.
- Low odour.
- Styrene free formulation.
PET (Polyethylene Terephthalate):
- Easy to recycle.
- Highly transparent (thicker layers give clearer results).