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Not all plastics are created equal, and when it comes to making the decision of which filament to buy, it’s important to keep some details in mind. The 3D printing that typically comes to mind for most people involved spoils of plastic filaments, usually ABS or PLA, but do people really know what these mean? This tutorial will dive into the basics of types of thermoplastics and how they differ in properties and uses.
PLA (Polylactic Acid) is one of the most common plastics used for 3D printer filament. The base material used to derive PLA is typically cornstarch, although various other countries use sugarcane and tapioca as sources as well. Unlike many other thermoplastics, PLA’s base materials are highly renewable (most other thermoplastics are derived from petroleum).
PLA is also biodegradable, as well as nontoxic in its solid form. It’s typical lifespan in the ocean is approximately between six months to two years, which is substantially less than other petroleum based plastics, taking between 500 - 1000 years to degrade. Outside of 3D printing, PLA has been used for food handling purposes as well as for medical sutures intended to biodegrade over time. When heated for printing however, it is recommended to avoid the risk of any vaporized plastics by working in a ventilated area or by using a printer with a casing.
Although PLA may seem like an excellent choice for its renewability and biodegradable properties, there are some other factors that must be taken into consideration. PLA is typically a more brittle thermoplastic in its solid state, and has a low glass transition temperature (111 - 145 °F), meaning that it will not retain its properties in high temperatures and should never be used for high temperature environments. However, PLA is more suitable than its popular counterpart of ABS because it contracts less with changes in temperature, making it easier to avoid warping in larger prints.
PLA is typically extruded at temperatures between 180 - 220 °C, and if your printer is equipped with a heat bed, a good range is typically between 60 - 70 °C. (Author note: experiment with different heat settings and printing speeds, when printing fast prints with large print areas, a higher heat may be a benefit).
PLA can be printed on glass, steel and blue tape beds. It is important to calibrate and test each surface with a print when changing between them.
ABS (Acrylonitrile Butadiene Styrene), as far as popularity goes, is another leader for 3D printer filament. As a thermoplastic, it is composed of three different petrochemical compounds; acrylonitrile, butadiene, and styrene, which make up its name. Petrochemicals are made from petroleum, which is the base for many plastic polymers. Its thermoplastic properties allow ABS to be melted and re-melted without losing its essential features. However, ABS is neither biodegradable nor renewable.
ABS is a hard and tough plastic, and is used frequently for its resistance to chemical corrosion. ABS is also highly resistance to greases and oils, although it is much less resistance to alcohols. Acetone can be used very effectively for smoothing ABS prints (see previous blog post on smoothing prints).
Although ABS is an excellent low cost filament with good resistance and finish, it has a tendency to act strangely with temperature fluctuations. People printing with ABS may find that their prints come out warped or misshapen. One way to avoid this is by making sure to print with ABS in an enclosed chamber, specifically on a heated bed at approximately 95-110 °C and with nozzle temperatures between 220 - 250 °C.
It is especially important to consider using a well ventilated area or to print in an enclosed chamber when printing with ABS because it produces toxic fumes that should not be inhaled. Many printers come with a glass or plastic enclosure; if you have access to a fume hood can create the same protective effect.
PETG (Polyethylene terephthalate with glycol) is a combination of PET with added glycol, which improves it properties. Most commonly used in plastic bottles for water, soda, and beers, PET is the most highly used plastic in the world. These plastics have been introduced into the world of 3D printing because of the ease at which they can be extruded, specifically PETG. While PET loses some of its important material properties when heated, PETG does not become fragile but rather remains durable and resistant to corrosion and wear. When compared to other filament materials, its characteristics are most similar to those of commonly used ABS, although its printing abilities are more similar to PLA.
PETG is known for its effectiveness in parts requiring some dynamic yield and flexibility. When printing with PETG, the recommended nozzle temperature range is approximately between 210 - 260 °C, and heat bed temperature between 60 - 80 °C. However, it is important to calibrate at a range of temperatures in your workspace because the environment you work in will have an impact on the quality of the print.
ASA (acrylonitrile styrene acrylate) is a less commonly used filament in most hobbyist and educational environments, because of its unique properties. As a thermoplastic, it is unique in its properties of mechanical strength, UV resistance, high glass transition temperature, and corrosion and wear resistance. Its mechanical strength allows ASA to be used for applications that may be exposed to higher impact environments, such as automotive and outdoor applications. UV resistance filament such as ASA does not experience discoloration and fading in the way that many other plastics might during long periods of exposure.
While ASA can be useful for hard-wearing applications, its costs can range in the higher end of the spectrum, making it most useful for industrial applications. Additionally, printing ASA requires very high extrusion temperatures and requires very good ventilation due to highly toxic fumes.
When printing ASA, temperature specifications will often depend on the specific filament purchased, as each have different specifications. The general nozzle temperature range sits approximately between 240 - 290 °C, and bed temperature sits between 80 - 120 °C.
PEEK (polyetheretherketone) is one of the more specialized plastics used for filament in 3D printers. Due to its capacity to retain properties at high temperatures, such as mechanical strength and stiffness, it can be used at temperatures ranging up to 170 °C. It can also be noted for its exceptional resistance to water and chemical corrosion, making it a viable option for engineered uses in a wide array of environments (PEEK is popular in the medical industry as well as for uses in the gas and oil industry).
Its high resistance to temperatures and chemical corrosion means that PEEK can be used for complex and specialty parts in engineering prototypes that may be more difficult to craft using traditional materials. PEEK is flame retardant as well.
The nozzle temperature range for PEEK is approximately 370 - 410 °C, and the heated bed temperature should be kept between 120 - 150 °C.
While PEEK has incredible properties for manufacturing specialized parts for a range of applications, it does not come cheaply. PEEK filament is high in the cost range of filaments, and has the additional challenge of finding a 3D printer that is built to withstand its temperature range.