Fused Deposition Modeling (FDM) 3D printers use filament as their primary building material. Filament is offered in spools that are available in multiple types of material, many of which are aimed at different printing purposes.
When a print is implemented, the filament is fed, from the spool, to the extruder, heated and then deposited out of the printer’s nozzle. The printer build’s the final object additively which is the process of adding the parts to the object a layer at a time.
The proper filament used will be largely determined by the intended application of the printed object. To aid in this determination, we will review the different types of filaments for 3D printing focussing on their characteristics, benefits and limitations. This should help to identify which filament will suit your project application with more confidence.
Types of 3D Printer Filaments
PLA Filament
Let us start with PLA (polylactic acid). PLA is not like the petroleum-based sources that most conventional filaments use its an organic renewable source. PLA is a thermoplastic which is easy to work with and relatively environmentally friendly.
PLA has the benefit of not warping during the printing process, which is why it is a go-to material for both beginners and experienced users. PLA is also food safe so its uses are broad.
Although PLA is not water-soluble, it can react to solvents like acetone, methyl ethyl ketone, and caustic soda. Overall, PLA is more brittle than many filaments and does not hold up well under long exposure to UV light.
ABS Filament
Acrylonitrile Butadiene Styrene (ABS) is one of the most popular kinds of engineering plastics in use today, and is particularly popular as a material for 3D printing. It has a reputation for toughness, while retaining enough integrity at elevated temperatures to make it usable for demanding applications.
These characteristics fit well with high-temperature requirements typical of operating ABS as a 3D printer filament. In order for the material to print correctly, both the hot end and the print bed must be heated to a sufficiently high temperature.
The releasable ABS print is highly dependent on a controlled, heated build environment. When this occurs, ABS is vulnerable to warping, and dimensional inaccuracies throughout the printing process.
Regarding properties, ABS is porous and retains some tensile strength and impact resistance, on scale with general location and repeated mechanical stress on the material.
ABS will not dissolve in water, like its organic predecessor PLA, but similar to PLA and its condition with moisture, the character of ABS is relevant, as certain organic solvents will dissolve ABS in common usage.
These solvents include acetone, methyl ethyl ketone (MEK), and esters (acids). Although the toxic organic solvents tend to dominate the general characterization of ABS, food safety also deserves mention. ABS has been classified as food safe, among a growing popularity of food-safe plastics.
Carbon Fiber Filament
Carbon fiber filaments are made with additives that improve certain mechanical strength characteristics or aesthetic parameters. The dimensional stability of a carbon fiber filament will be superior to some other filaments; additionally, they will still remain less likely to warp during printing.
When carbon fiber is added to materials like ABS, it will improve the overall durability, but it makes the material more brittle, and typically can clog a nozzle. Also, carbon fiber filaments will dissolve with organic solvents.
Nylon Filament
Nylon (polyamide) is differentiated from other engineering plastics by its hardness, durability and wear-resistance. Of the numerous varieties of nylon, the most commonly used by hobbyists is PA 6. The qualities that make nylon desirable are its dual properties of impact strength and wear resistance.
Another factor to consider with nylon is that it will absorb moisture fairly easily and typically prints at higher temperatures, sometimes as high as 265℃. Food-safe formulations, if safety is a concern, are readily available.
Despite its advantages, nylon has some disadvantages. Its hygroscopic property allows for expansion if exposed to water. It has been reported to dissolve in a limited number of solvents (e.g., acetic acid and formic acid). Enough heat at elevated temperatures has also been noted will incur some warping. A heated enclosure may be helpful to some extent on the warping issue.
FLEX Filament
FLEX filament is a proprietary blend of two polymers designed to create a flexible copolymer for 3D printing. FLEX filament is in the thermoplastic polyurethane (TPU) family, and has a shore A hardness of 93 A when printed.
In layman’s terms, printed parts made with FLEX filament are flexible, and have significant impact resistance. One key thing to take in consideration is that FLEX filament is hygroscopic; it tends to absorb moisture from the air which could result in catastrophic failure while printing.
It is always prudent to dry the filament before printing and to keep it dry during long prints. Like any flexible materials, FLEX filament is also very durable, and will not warp when in use.
HIPS Filament
High-impact polystyrene (HIPS) is a thermoplastic commonly used for pre-production machining prototypes because its properties are nearly the same as ABS, which is the reason HIPS is frequently used as a support material in conjunction with ABS components.
In real life, HIPS is characterized by its ability to withstand durability, flexibility and strength. HIPS is also food safe and can be dissolved using D-limonene. However, be aware of the fumes generated while printing material, as they may be environmentally unsafe and should be handled in a well-ventilated area.
Some users may find it necessary to build a duct to vent fumes outside. Another concern with HIPS is that it has a high tendency of warping if temperature is not controlled accurately. Because of this, heated enclosures are typically recommended when working with HIPS.
PVA Filament
This particular plastic filament is recognized for its biodegradability and its ease of use in addition to better properties of warping resistance than most other materials. Polyvinyl Alcohol (PVA) material is commonly used alongside PLA as a support material because it is soluble in water and will break down when exposed to water.
However, its ease of use means that you will lose usability in moisture from PVA exposure, which limits its use for most functional purposes. What is important to emphasize is that PVA has limitations for food applications and, while it should be pretty common, it is relatively more expensive than many other filaments options.
PETG Filament
Polyethylene terephthalate glycol-modified (PETG) is essentially an improved variant of PET that includes glycol in the manufacturing of the resin.
The glycol helps reduce the melting temperature of the material, allowing PETG to be generally easier to work with than PET, in most printing environments. One of the nice features of PETG is that it is resistant to ultraviolet light.
However, PETG has somewhat of a couple of quirks, layer bonding is typically not very strong, and it does tend to string finer lines of material across open spaces while printing.
Nonetheless, PETG still has most of the characteristics that make PET useful, it is tough, somewhat resistant to warping under standard conditions, and it is considered food safe. As for its solvent properties, PETG will dissolve in solvents like toluene, methyl ethyl ketone.
TPE Filament
Thermoplastic elastomers are quite flexible and also compatible with melt processing in most 3D printers. TPE is often confused with TPU, but TPE is generally considered to have a softer hardness rating than TPU.
TPE has excellent flexibility and abrasion resistance. It will keep its form and not warp, is very elastic, and sticks well to itself, and other materials. The table below lists the mechanical properties of TPE based on the FilaFlex TPE filament.
PC Filament
Polycarbonate, known as PC, is one of the strongest and most reliable types of 3D printing filament. This engineering thermoplastic has excellent mechanical strength and in addition has a high glass transition temperature of 150℃, which means it will perform excellently even when doing sustained applications with heat.
As with ca 3D printed material, print temperature settings when using polycarbonate filament can be extremely high, up to 310℃, to get the best quality results. The filament is food safe and will dissolve in certain chemicals such as tetrachloromethane, chloroform, and pyridine.
There are some considerations: ultra-high filament warpage can occur when printing with polycarbonate, and because polycarbonate is hygroscopic, it readily absorbs moisture from the surrounding air. If this moisture is not resolved before printing it might affect the quality of the printed object.
Polycarbonate filament is often found as standard PC filament or as biocompatible PC-ISO, the later would be suitable when biocompatibility is important and could be subsequently used for some medical devices.