In order to be extruded by the 3D printer, these thermoplastics are transformed into filament which can then be driven and melted by the extruder. Today, most plastics in industry can undergo this transformation, expanding the field of possibilities. But how do you choose your 3D printer filament? What are the characteristics to take into account?
Before moving on to the different filaments that exist in the additive manufacturing market, it is important to understand how plastics are classified, a first step that will allow you to see more clearly. Today, there are so-called amorphous or semi-crystalline plastics: these adjectives define the intermolecular structure of the polymer, depending on how they react when they solidify following fusion. In concrete terms, the chains of amorphous plastics will become entangled and remain disordered during the solidification phase. Conversely, the chains of semi-crystalline will organize and arrange themselves in relation to each other. From this will flow various properties; Amorphous materials, for example, are generally more transparent and have lower dimensional stability. Finally, another important point that orders the family of plastics is the melting temperature: standard plastics will have a lower temperature than so-called technical materials. High-performance polymers will require more advanced thermal management, with melting temperatures close to 300°C.
Standard 3D printer filaments
Le PLA
PLA, or polylactic acid, is a semi-crystalline material made from renewable resources – usually corn starch. Unlike the majority of plastics from the oil industry, PLA is considered to be greener because it is biodegradable under the right conditions. It is a very easy-to-use 3D printer filament, which is why it is very popular in the 3D printing market. Compatible with food contact, its extrusion temperature is generally 180°C. It has good geometric stability and is generally not prone to warping. It is mainly used in prototyping, tooling, decorative parts and in the medical sector. PLA is available in several colors and is often used as a matrix of a composite material.
Polypropylene
PP is one of the most widely used materials in plastic injection, renowned for its lightness, resistance to chemicals, fatigue and good electrical insulation. It is also found in the form of a filament for 3D printers, offering good impact resistance, gas tightness and semi-rigidity. Note, however, that it is quite difficult to print because it does not adhere to the tray. It has very precise melting points and will require excellent thermal management. In terms of applications, choose PP filament to design packaging, clamps and fasteners, liquid tanks, etc.
ABS, a widely used 3D printer filament
This time, we move to an amorphous structure: ABS is a filament renowned for its resistance to shocks at low temperatures and its lightness. It is not always easy to classify this material: it is sometimes in the technical part of the pyramid, less easy to process than PLA, for example. In 3D printing, it is prone to warping, requiring the use of a heated bed. Its properties make it an ideal material for the production of functional prototypes, tooling parts that are often stressed or in the manufacture of molds. ABS remains an accessible filament for 3D printers, with a wide range of products.
Technical filaments
Nylon
Nylon, also known as polyamide (PA), is more prevalent in the additive manufacturing market in powder form for SLS technology. However, it can be found in the form of a filament, available with 6 carbon atoms, hence PA6. The latter is similar to ABS, also requiring a heated bed because its grip is not the best. PA6 is renowned for its impact and abrasion resistance as well as its flexibility. It has a fairly long service life, ideal for the production of parts like hinges, machine components, and tooling. It can be reinforced with carbon or glass fibers. Note that nylon is a material that absorbs moisture: its storage in a dry place is essential.
PET, a more technical filament for 3D printers
PET is a well-known material in the industry since it is used in today's plastic bottles. In 3D printing, it is better known in the form of PETG, i.e. with the addition of glycol to reduce its brittle appearance. It is mainly known for its transparency and compatibility with food contact. For example, many packages and containers are printed with PETG. It is a good alternative to PLA or ABS.
The POM
Polyoxymethylene, or POM, is a semi-crystalline that is becoming more and more talked about in 3D printing. It has excellent chemical properties, is resistant to heat, impact and abrasion and has good sliding properties. This means that you can 3D print a variety of applications with POM, such as backpack buckles, elements that need to withstand heat over time, or cogwheels. It is a filament that is still quite difficult to print because it requires good thermal management – tray, extruder and chamber. Also note that there are few manufacturers of this type of filament for 3D printers compared to materials such as PLA or ABS.
Polycarbonate, an amorphous 3D printer filament
Polycarbonate (PC) is mainly used for its strength and transparency. It is not an easy thermoplastic to print as it requires higher extrusion temperatures as well as a heated bed. It is particularly popular in the optical sector because it is less dense than glass and can withstand temperatures ranging from -150°C to 140°C. Typically, protective screens or optical parts can be 3D printed with polycarbonate. In any case, this filament for 3D printers is becoming more and more widespread in the offer of manufacturers in the sector.
High-performance thermoplastics (HPP)
This last category of polymers is known to be more demanding: the thermoplastics that make it up require high melting temperatures and have characteristics that are similar to those of certain metals. In additive manufacturing, these are filaments that will need a high extrusion temperature, a heating bed and a closed enclosure. Thermal management is essential for this type of material.
Semi-crystalline PPH
PEEK is arguably the most common 3D printer filament in this category. Belonging to the PAEK family, it requires an extrusion temperature of around 400°C, a platter that can reach 230°C and an enclosure heated to 120°C. PEEK is renowned for its strength-to-weight ratio and can withstand high temperatures. It is sterilizable, making it a material of choice for printing custom implants. It is a filament for 3D printers that remains demanding, requires a certain mastery of the 3D printing process and remains quite expensive.
PPS is also a semi-crystalline high-performance thermoplastic, renowned for its chemical resistance and mechanical properties. It is mainly used in the automotive, oil gas and electronics sectors. Its extrusion temperature is more around 300°C; It also requires a heating bed and a closed enclosure.
Amorphous high-temperature filaments
In this category, we can first mention PEI, a 3D printer filament now marketed by SABIC under the brand name ULTEM. Less expensive than PEEK, it meets fire/smoke standards, making it an ideal material for the aerospace sector. PEI is also resistant to automotive fluids, hydrocarbons, alcohols and aqueous solutions. It can be sterilized and compatible with food contact.
Finally, we can mention here the family of sulfones, in particular PPSU and PSU. They are very interesting thermoplastics in terms of thermal properties and fire/smoke characteristics. They also have good electrical insulation and dielectric properties. These are materials that are popular in the transportation industry, whether rail, aerospace or automotive.
Composite and flexible 3D printer filaments
Finally, it is important to mention composite filaments and elastic materials. As for composites, they are materials composed of a matrix – PLA, nylon, polycarbonate, etc. which is reinforced with fibers, most often carbon. We can also have glass, aramid, etc. These will increase the resistance of the filament while optimizing its weight. You should know that there are different methods of placing fibers today, which are more or less long.
Finally, flexible filaments such as TPU filament are part of the FDM material offering. They are flexible materials known for their resistance to wear and impact. They are particularly interesting in the production of pliers or orthopaedic insoles. Be careful, however, they are sensitive to high temperatures.
