What filaments are used for fused deposition modeling?
During the past three decades of research, scientists and engineers have presented a vast selection of materials to use as filaments for FDM.. All materials offer both advantages and challenges for the user selection, as well as diverse levels of advancement in technology, hardware requirements, and best practices to succeed in the material selection of a specific project. Here is a brief description of some of the most common FDM filaments available on the market.
Polylactic acid (PLA)
PLA is a biodegradable thermoplastic polyester made from naturally renewable sources, such as corn, sugarcane, wheat, or other high-carbohydrate sources. PLA is, at present, the most adopted material in 3D printing. Due to its eco-friendly features, it is well suited for food packaging applications and for surgical and medical applications [4][5].
Table 1. Advantages and limitations of PLA.
| Advantages | Limitations |
| Can be extruded by low-energy and cost-effective 3D printers | High brittleness |
| Biodegradable | Low toughness and durability |
| Requires lower printing temperature and low shrinkage | Low service temperature |
| Available in the market in a variety of colours and textures | Cause for nozzle clogging |
| Non-toxicity |
To overcome the limitations, researchers, over the last two decades, have investigated and blended PLA with other polymers, such as blends of poly L-lactide (PLLA) and poly D-lactide (PDLA) [5]. Blending PLLA and PDLA resulted in the formation of poly(lactide) stereo complex crystallites (SC) [6]. The stronger interactions in SCs induced higher melting temperatures and increase crystallization speed; thus, improving the thermo-mechanical properties [6][7]. The result of these blends lead to the development of hot-fill packaging and microwave applications.
Acrylonitrile butadiene styrene (ABS)
ABS is a thermoplastic polymer produced by the fusion of styrene and acrylonitrile in the presence of polybutadiene [7]. It is the second most common material used for FDM filaments after PLA.
ABS is a suitable option for parts that need to resist cyclic loading and temperature changes [9]. Some typical applications of ABS filaments in 3D printing are surgical models, prototypes, toys, and kitchen appliances. ABS’s good mechanical characteristics that allow it to hold up for extensive usage and wear have made it an excellent choice for products like the LEGO building blocks.
Table 2. Advantages and limitations of ABS.
| Advantages | Limitations |
| High impact resistance | Warping, curling, and cracking during printing |
| Good abrasion and strain resistance | Produces toxic gases |
| Good chemical resistance | Can be damaged by sunlight |
| Resistant to temperatures | |
| Long service life | |
| Good electrical insulating properties | |
| Surface aspect and brightness offering a gloss feature |
Polyethylene terephthalate (PET)
PET is a petroleum derivative thermoplastic from the polyester family. PET’s Glycol modified version, PETG, is among the most employed materials for FDM alongside PLA and ABS. Designers and engineers are taking advantage of its unique properties, such as transparency, moisture resistance, and chemical resistance, to create attractive applications for liquid containers, food storage, graphic displays, prototypes, and textiles [10].
Table 3. Advantages and limitations of PET.
| Advantages | Limitations |
| High chemical resistance | Possible curling during printing |
| Moisture resistance | Limited mechanical resistance, not suitable for structural applications |
| Good durability | Its relatively soft surface makes it prone to wear |
| Glossy and smooth surface finish | |
| Minimal warping effect |
Thermoplastic polyurethane (TPU)
TPU is a very flexible, abrasion-resistant, and versatile thermoplastic that is used in diverse industrial applications. Due to its ability to stretch and bend, it can be considered as a bridge between rigid plastic and elastic rubber [11]. It is commonly used in automobile applications, sporting goods, power tools, and film and sheet applications.
Table 4. Advantages and limitations of TPU.
| Advantages | Limitations |
| Very high flexibility and elasticity to create complex elastic designs or specific shapes | Relatively high difficulty during the printing process due to its flexibility |
| High durability and strength | |
| High resistance to abrasion |
Poly-ether-ketone (PEEK)
PEEK is a high-performance, semi-crystalline, thermoplastic polymer, and a member of the Poly-aryl-ether-ketone (PEAK) family. This material has a special combination of engineering properties that makes it ideal for metal (aluminum or steel) replacement applications, particularly in the aerospace, automobile, and healthcare industries. Good examples of applications are metal implants and the manufacturing of out-of-earth replacement parts, such as those used in the International Space Station (ISS) [12][13][14].
Table 5. Advantages and limitations of PEEK.
| Advantages | Limitations |
| Chemical and biological stability | Poor resistance to UV radiation |
| Superior thermal resistance | Difficult to process due to its semi-crystalline structure |
| High mechanical performance | Requires high levels of expertise to limit printing issues |
| Can be sterilised (ideal for surgical and dental applications) | Limited equipment suitable to process |
Polyphenylsulfone (PPSU)
PPSU is a high-temperature sulfone polymer. PPSU’s high performance allows it to be used in applications for healthcare, smart devices, energy storage, and aerospace [14].
Table 6. Advantages and limitations of PPSU.
| Advantages | Limitations |
| Excellent thermal, chemical, and impact resistance | Requires high levels of expertise to limit printing issues |
| High gamma-radiation resistance and flame resistance | |
| Sterilization capability | |
| High strength and high modulus, even at high temperatures |
Other FDM filaments
Several additional filaments available for FDM are listed below [15].
High Impact Polystyrene (HIPS): HIPS is a lightweight material that is dissolvable and is mainly used as a support structure for ABS models.
Acrylonitrile Styrene Acrylate (ASA): ASA is a polymer with similar characteristics to ABS and high UV resistance, which makes it a great option for outdoor applications.
Carbon-Fiber Filled Filaments: These are tiny fibers infused into the base filament (PLA or ABS) to improve strength and stiffness properties. Some filaments can be acquired with carbon fiber fills, including PLA, PETG, Nylon, ABS, and Polycarbonate.
Wood-Filled Filaments: These are filaments with a composite such as cork or wood dust, to produce the aesthetics of real wood.