Fused Deposition Modeling (FDM) is one of the most widely used 3D printing processes on the market due to its ease of use, accessibility, and performance. It is known especially for its compatibility with a wide variety of thermoplastics, that is, materials that are capable of softening under the effect of heat but that return to their initial shape when cooled. To be extruded by the 3D printer, these thermoplastics are made into a filament that can then be propelled and melted by the extruder. Today, most of the plastics in the industry can undergo this transformation, thus expanding the field of possibilities. But how do you choose your filament for your 3D printer? What characteristics must be taken 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 crucial first step that will help you better understand the available materials and their characteristics. 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 melting. Specifically, the chains of amorphous plastics become entangled and remain disordered during the solidification phase. On the contrary, chains of semi-crystalline plastics will organize and dispose of each other. Different properties will result from this; 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 the so-called technical materials. High-performance polymers, on the other hand, require more advanced thermal management, with melt temperatures approaching 572°F (300°C).
Standard 3D Printer Filaments
PLA, or polylactic acid, is a semi-crystalline material derived from renewable resources, usually corn starch. Unlike most oil industry plastics, PLA is considered more environmentally friendly 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 usually 180°C. It has good geometric stability and is generally not subject to deformation. It is mainly used for prototypes, tools, decorative pieces or in the medical sector. PLA is available in a variety of colors and is often used as a matrix for composite materials.
PP is one of the most widely used materials in plastic injection moulding, known for its light weight, resistance to chemicals and fatigue, and good electrical insulation. It is also available in the form of filament for 3D printers, offering good impact resistance, gas tightness and semi-rigidity. Note, however, that it is quite difficult to print as it does 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 fasteners, liquid containers, etc.
ABS, a popular filament for 3D printers
This time we move on to an amorphous structure: ABS is a filament known for its resistance to low-temperature shocks and its lightness. It is not always easy to classify this material: it is sometimes found in the technical part of the pyramid and is less easy to process than PLA, for example. In 3D printing, it is subject to warping, which requires the use of a heating plate. Its properties make it an ideal material for the production of functional prototypes, frequently requested tooling parts, or in mold making. ABS remains an affordable 3D printer filament, with a wide range of options.
Nylon, also known as polyamide (PA), is most prevalent in the additive manufacturing market in powder form for SLS technology. However, it can be found in a filament form, available with 6 carbon atoms, hence PA6. The latter is similar to ABS, also requiring a hot plate because its adhesion is not the best. PA6 is known for its resistance to impact and abrasion, as well as its flexibility. It has a fairly long life, ideal for the production of parts such as hinges, machine components and tools. It can be reinforced with carbon or glass fibers. Keep in mind that nylon is a moisture-wicking material, so it’s important to store it in a dry place.
PET, a more technical 3D printer filament
PET is a well-known material in the industry, since it constitutes the current plastic bottles. In 3D printing it is better known in the form of PETG, that is, with the addition of glycol to reduce its brittle appearance. It is primarily 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.
Polyoxymethylene, or POM, is a semi-crystalline material that is becoming increasingly popular in 3D printing. It has excellent chemical properties, is resistant to heat, impact and abrasion and has good sliding properties. POM can be used to 3D print a variety of applications, such as backpack buckles, components that need to resist heat over time, or gears. However, it is a filament that is still quite difficult to print because it requires good thermal management: plate, extruder and chamber. Also keep in mind that there are few manufacturers of this type of filament for 3D printers compared to materials such as PLA or ABS.
Polycarbonate, an amorphous filament for 3D printers
Polycarbonate (PC) is mainly used for its strength and transparency. It is not an easy thermoplastic to print because it requires higher extrusion temperatures and a heating plate. It is particularly popular in the optical industry because it is less dense than glass and can withstand temperatures ranging from -238°F to 284°F (-150°C to 140°C). Protective screens or optical parts can usually be 3D printed with polycarbonate. In any case, this filament for 3D printers is becoming more and more common in the range of products offered by manufacturers in the sector.
High Performance Thermoplastics (HPP)
This last category of polymers is known to be more demanding: the thermoplastics it contains require high melting temperatures and have characteristics close to those of certain metals. In additive manufacturing, these are filaments that will need a high extrusion temperature, a heating plate, and a closed enclosure. Thermal management is crucial for this type of material.
PEEK is probably the most common 3D printer filament in this category. Belonging to the PAEK family, it requires an extrusion temperature of approximately 752°F (400°C), a plate that can reach 446°F (230°C), and an enclosure heated to 248°F (120°C). PEEK is known for its strength to weight ratio and can withstand high temperatures. It can be sterilized, making it the material of choice for printing custom implants. It is a filament for 3D printers that is still demanding, requires some mastery of the 3D printing process and is still quite expensive.
PPS is also a high-performance, semi-crystalline 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 more than 572°F (300°C); it also requires a heating plate and a closed chamber.
High temperature amorphous filaments
In this category we can first mention PEI, a filament for 3D printers now marketed by SABIC under the ULTEM brand. Less expensive than PEEK, it 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 compatible with food contact.
Finally, we cannot forget the sulfone family, in particular PPSU and PSU. These are very interesting thermoplastics in terms of thermal properties and fire/smoke characteristics. They also have good electrical insulation and dielectric properties. They are popular materials in the transportation industry, including rail, aerospace, and automotive.
Flexible Composite 3D Printer Filaments
Finally, it is important to mention composite filaments and elastic materials. Composites are materials composed of a matrix (PLA, nylon, polycarbonate, etc.) and reinforced with fibers, most of the time carbon. Glass, aramid, etc. can also be used. These will increase the strength of the filament while optimizing its weight. There are different methods of placing the fibers, although they are usually more or less long.
Finally, flexible filaments such as TPU are part of the FDM material offering. These are flexible materials known for their resistance to wear and impact. They are particularly interesting in the production of orthopedic braces or insoles. However, they are sensitive to high temperatures.
*Thumbnail photo credits: AGRU
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