Fused Deposition Modeling (FDM) is one of the most widely used 3D printing processes on the market because of its ease of use, accessibility, and performance. It is particularly known for its compatibility with a large number of thermoplastics, ie materials that can soften when exposed to heat, but return to their original shape when cooled. In order to be extruded by the 3D printer, these thermoplastics are converted into a filament, which can then be driven and melted by the extruder. Today, most plastics in industry can go through this transformation and thus expand the field of possibilities. But how do you choose your filament for your 3D printer? Which properties have to be considered?
Before moving on to the various filaments in the additive manufacturing market, understanding how plastics are classified is a crucial first step in helping you better understand the materials available and their properties. Today there are so-called amorphous or semi-crystalline plastics: These adjectives define the intermolecular structure of the polymer based on how they react when they solidify after fusing. The chains of amorphous plastics in particular become entangled and remain disordered during the solidification phase. Conversely, the chains of semi-crystalline plastics organize and arrange themselves with one another. This results in different properties; amorphous materials, for example, are usually more transparent and have a lower dimensional stability. Another important point of the plastic family is the melting temperature: Standard plastics have a lower temperature than so-called technical materials. High performance polymers, on the other hand, require more advanced thermal management, with melt temperatures near 572 ° F (300 ° C).
Standard 3D printer filaments
PLA or polylactic acid is a semi-crystalline material that is obtained from renewable raw materials – usually corn starch. Unlike most plastics from the petroleum industry, PLA is considered more environmentally friendly because it is biodegradable under the right conditions. This 3D printer filament is very easy to use which is why it is very popular in the 3D printing market. Suitable for food contact, its extrusion temperature is normally 180 ° C. It has good geometric stability and is generally not subject to any warpage. It is mainly used for prototype construction, tool making, decoration parts or in the medical field. PLA is available in a variety of colors and is often used as a matrix for composite materials.
PP is one of the most commonly used materials in plastic injection molding, known for its lightness, chemical and fatigue resistance, and good electrical insulation. It is also found in the form of filaments for 3D printers and offers good impact resistance, gas tightness and semi-rigidity. Note, however, that it will be quite difficult to print as it will not stick to the plate. It has very precise melting points and requires excellent thermal management. In terms of applications, PP filament is best used for packaging, clips and closures, liquid containers, etc.
ABS, a popular 3D printer filament
This time we move on to an amorphous structure: ABS is a filament known for its resistance to low temperature shocks and its lightness. This material is not always easy to classify: it is sometimes in the technical part of the pyramid and is less easy to process than PLA, for example. In 3D printing, it is subject to warpage, which requires the use of a heating plate. Its properties make it an ideal material for the production of functional prototypes, frequently requested tool parts or in mold making. ABS remains an affordable 3D printer filament with a wide variety of options.
Nylon, also known as polyamide (PA), is more common in the powder additive manufacturing market for SLS technology. However, it is available in filament form, available with 6 carbon atoms, hence PA6. The latter is similar to ABS and also requires a heating plate as its adhesion is not the best. PA6 is known for its impact and abrasion resistance as well as its flexibility. It has a fairly long lifespan, ideal for making parts like hinges, machine components, and tools. It can be reinforced with carbon or glass fibers. Note that nylon is a moisture absorbent material, so it’s important to keep it in a dry place.
PET, a more technical 3D printer filament
PET is a well-known material in the industry as it is what defines today’s plastic bottles. In 3D printing, it is best known in the form of PETG, i.e. with the addition of glycol to reduce the brittle appearance. It is best known for its transparency and food tolerance. Many packaging and containers are printed with PETG, for example. It’s a good alternative to PLA or ABS.
Polyoxymethylene or POM is a semi-crystalline material that is becoming increasingly popular in 3D printing. It has excellent chemical properties, is heat, impact and abrasion resistant and has good sliding properties. POM can be used to 3D print a wide variety of applications, such as backpack buckles, components that need to withstand heat over time, or gears. However, it’s a filament that is still quite difficult to print as it requires good thermal management – roller, extruder, and chamber. Also note that there are few manufacturers of this type of 3D printer filament compared to materials like PLA or ABS.
Polycarbonate, an amorphous 3D printer filament
Polycarbonate (PC) is mainly used for its strength and transparency. It is not an easy-to-print thermoplastic as it requires higher extrusion temperatures and a hot plate. It is particularly popular in the optical industry because it is less dense than glass and can withstand temperatures from -238 ° F to 284 ° F (-150 ° C to 140 ° C). Typically, protective panes or optical parts can be 3D printed with polycarbonate. In any case, this 3D printer filament is increasingly found in the product range of manufacturers in the industry.
High-performance thermoplastics (HPP)
This last category of polymers is known to be more demanding: the thermoplastics they contain require high melting temperatures and have properties that are similar to those of certain metals. In additive manufacturing, these are filaments that require a high extrusion temperature, a heating plate and a closed housing. Thermal management is critical for this type of material.
PEEK is probably the most common 3D printer filament in this category. It belongs to the PAEK family and requires an extrusion temperature of about 752 ° F (400 ° C), a plate that can reach 446 ° F (230 ° C), and a housing that can reach 248 ° F (120 ° C) is heated. PEEK is known for its weight / strength ratio and can withstand high temperatures. It can be sterilized and is therefore the material of choice for printing custom implants. It’s a filament for 3D printers that remains sophisticated, requires some mastery of the 3D printing process, and remains quite expensive.
PPS is also a semi-crystalline high-performance thermoplastic known for its chemical resistance and mechanical properties. It is mainly used in the automotive, oil and gas, and electronics industries. Its extrusion temperature is about 572 ° F (300 ° C); it also requires a hot plate and an enclosed chamber.
Amorphous high temperature filaments
In this category we can first mention PEI, a filament for 3D printers that is now marketed by SABIC under the ULTEM brand. It’s less expensive than PEEK and meets fire / smoke standards, making it an ideal material for the aerospace industry. PEI is also resistant to automotive fluids, hydrocarbons, alcohols and aqueous solutions. It can be sterilized and is suitable for contact with food.
Finally, we must not forget the family of sulfones, especially PPSU and PSU. These are very interesting thermoplastics in terms of thermal properties and fire / smoke properties. They also have good electrical insulation and dielectric properties. They are popular materials in the transportation industries, including rail, aerospace, and automotive.
Composite and flexible 3D printer filaments
Finally, it’s important to mention composite filaments and elastic materials. Composites are materials made up of a matrix – PLA, nylon, polycarbonate, etc. – and reinforced with fibers, mostly carbon. Glass, aramid, etc. can also be used. These increase the strength of the filament and at the same time optimize its weight. There are several methods of placing the fibers, although they are usually more or less long.
After all, flexible filaments such as TPU are part of the FDM material range. These are flexible materials that are known for their wear and impact resistance. They are of particular interest in the manufacture of brackets or orthopedic insoles. However, they are sensitive to high temperatures.
* Photo credits for thumbnails: AGRU
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