Different materials for 3D Printering
Different materials for 3D Printering
Fused Deposition Modeling (FDM) has been the choice of 3D Printing technology for DIY and hackers, because of its low cost, hackability and low cost of input material. As key patents in the FDM space expired around 2000, Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) as feed material become very popular. ABS being more flexible than PLA also is considered an engineering grade plastic. PLA as compared to ABS is more rigid, but the downside is that it is brittle. To print an ABS part strict thermal conditions need to be maintained in the build chamber, where such conditions are not required for PLA and therefore PLA is the prefered material for users getting introduced to 3D Printing.
High Impact Polystyrene (HIPS)
HIPS is a dissolvable filament in D-limonene solution. It is usually used in combination with ABS as a support material, as both their melting temperature range (~220–240 °C) and glass transition temperature (~70–90 °C) is similar. It warps less than ABS and it has better impact resistance and hardness. It also has good dimensional strength and heat resistance. Post processing on HIPS is also as easy as ABS, it can be sanded, primed and painted for finishing.
Nylon
Nylon is an excellent choice for making 3D Printed parts which require very high mechanical strength. It is strong, durable and flexible when the 3D Printed part is very thin. The interlayer adhesion is also very strong, making it very useful to print hinges, gaskets and parts that take a lot of pressure and load. It’s low friction coefficient and high melting point make it an excellent candidate for 3D printed gears. Nylon when used with carbon fibres in 3D printing, gives similar strength as that of parts made by carbon fibre via traditional methods of manufacturing. Nylon requires a higher temperature between 235–275 °C for printing. Traditional extruders come with PTFE tubes or made with PEEK. At 240 °C these materials will start distorting and fumes will get emitted. All metal extruders are the best option for Nylon. The bed has to be heated between 60–80 °C. Furthermore, it will require a PVC based adhesive for it to stick on the heated bed.
Nylon filament is hygroscopic, absorbs a lot of moisture, close to 10% of its weight. Moist nylon filament if used for 3D Printing will contain bubbles and distorts the part finishing, layer adhesion is also weak and may cause cracking. Dry nylon has a very smooth part finish and maintains all its mechanical strength. To remove the moisture from the filament dry it in an oven at 180–200 °F for 6 to 8 hours.
Nylon warps in a similar manner as ABS. On a heated glass plate with temperature set to ~70 °C, and printing temperature of ~250 °C and a speed of ~40mm/s warping can be reduced to a lot of extent. Using a PVA based glue also allows for better bed adhesion and reduces warping.
Plasticized Copolyamide Thermoplastic Elastomer (PCTPE)
This filament is a combination of flexible nylon and thermoplastic elastomer (TPE). The parts are very flexible and have the necessary durability of nylon parts. It’s printing temperature is around 230 °C with a heated bed maintained at around 40 °C. The glass transition temperature is around 75 °C. Some manufacturers have added an extra “draw” process in the last manufacturing stage. This added stage increases tensile strength of the filament such that buckling or folding of prints is eliminated. Here the % of TPE can also be increased so as at increase the flexibility of the prints. An enclosure is not required to get better bonding for parts with thin walls.
Thermoplastic Elastomer (TPE) V.S. Thermoplastic Polyurethane (TPU)
Both TPU and TPE are flexible thermoplastics and they differ in their mechanical properties. TPE is very flexible and soft and has a shore hardness of ~85A. It has rubber like properties. You can stretch it to twice its length without any major deformation.
TPU on the other hand is a slightly more rigid thermoplastic than TPE. It has a shore hardness of ~94A.TPE being quite soft some 3D Printer extruders might find it difficult to print with it. The gears will press too much against the filament and the filament will start grinding. TPU on the other hand being a slightly more rigid filament these problems are mitigated and gives a better 3D Printing experience. Furthermore, TPU has higher abrasion resistance than TPE. Therefore parts printed with TPE have a longer life as wear and tear is less. It also retains its elasticity at lower temperatures. TPU is also more popular in the industry. It has higher resistance to oil and grease. It also has a lower shrinkage value of 0.8–1.8% as compared to TPE which is 1.2–3.0%, allowing TPU to give you more accurate parts. Both TPU and TPE are quite resistant to ozone and outside weather temperature. The combination of these flexible thermoplastics with those that are rigid will allow 3D Printing users to have use cases in producing parts where systems can be printed with both rigid and flexible parts.