3D printing is a well-established solution, although a lot of people still perceive it as something innovative and fresh. The possibility to print entire objects from scratch has vastly changed not only the way we think of prototyping but also the whole process of executing such projects. Just like a traditional printer needs a cartridge or toner to operate properly, a 3D printer cannot operate without a filament which can have different properties that are worth considering when selecting the material.
What are 3D printing filaments?
3D printing filaments are thermoplastics used for printing three-dimensional objects through the process of building up the melted material by the 3D printer. They are available in different types and colours, made of e.g. ABS (acrylonitrile butadiene styrene), PLA (polylactide), PET (polyethylene terephthalate), nylon, and many others. They are supplied in the form of coils that are wound on rolls and then inserted into a 3D printer. The thermoplastic is unreeled and fed through the nozzle, which is heated to a temperature at which it melts. The nozzle, controlling the flow of the thermoplastic, moves around as per the programmed (e.g. with CAM) instruction. This resembles stereolithography (SLA), which also involves applying subsequent laser-cured layers. 3D printing is used in more and more fields, generating a growing list of filaments available on the market. Some are made from natural raw materials, other ones are synthesised entirely from plastics. All the types have one thing in common: they take on the form of thin, dozens or even hundreds of metres long fibres that are wound onto the spools of different sizes. The spools are convenient to mount and demount in the printer and (thanks to their side covers) protect the fibres from slipping off.
Filaments from renowned suppliers are available in two basic fibre diameters: 1.75 mm and 2.85 mm. They are usually made neatly and are free of any random coarsening and irregularities. This is crucial for the printing process quality, as every instance of coarsening means a surplus of material in the nozzle and slightly different behaviour of the material when applied. It is worth remembering here that the thickness of a typical single layer is about 80% of the nozzle diameter, usually slightly less than 0.5 mm (e.g., for a Ø 0.4 mm nozzle, the obtained layer is 0.32 mm).
Features of the most important filament types
There are many types of filaments and thus many types of materials that they are made of. However, there is one group that could certainly be called the most popular, which is worth knowing when undertaking work with 3D printers:
ABS (acrylonitrile butadiene styrene)
This is one of the most popular types of 3D printing filaments. ABS is durable and resistant to compression and abrasion and performs well at high temperatures. It’s the perfect choice for printing elements that are exposed to long-lasting use in challenging conditions. It may, however, be difficult to work with and it may emit hazardous and unpleasant odours during printing. It also requires the use of a heated print bed and glue, as it is prone to distortion otherwise. Its printing temperature ranges from 210 to 250°C.ABS filaments are made in the course of the thermoplastic synthesis process. It involves mixing three components: acrylonitrile, butadiene and styrene in a special device called a continuous mixer, in order to obtain a homogenous mass. The mass is heated to a high temperature to melt it and then fed through the nozzle, which forms thin fibres. The next step involves winding the fibres on rolls. Proper mixing of components and correct melting and forming of the fibres is crucial for obtaining high-quality fibres which will perform well in 3D printers.
Typical applications of ABS include, among others, household appliances, bike helmets and building blocks for children. ABS is also used to make all types of enclosures, covers, handles, levers or minor finishing elements. Importantly, though, the material should not have any contact with food.
PLA (polylactide)
This is a non-toxic and biodegradable type of filament, easy to process and safe for the environment, which is why nowadays it’s the most popular variant of 3D printing filaments. PLA is more flexible and less resistant to high temperatures than ABS. At the same time, it’s easier to print, as it’s not prone to distortion, does not require a heated print bed, and needs lower printing temperatures (180–230°C). It also does not emit unpleasant odours. PLA has a wide scope of applications, which include, for example, display products (figurines) or construction components, and that is why it’s available in many colours. PLA filaments are made during the thermoplastic synthesis process. This process involves mixing natural raw materials (e.g. corn starch) with chemical additives, such as lactic (polylactic) acid, and polyethylene glycol. This mass, just like in the case of almost all filaments, is heated to a high temperature and then fed through the right nozzle, which forms it into thin fibres. The next step involves cooling down the fibres and winding them onto rolls.
An important issue is that PLA has low resistance to higher temperatures, so the elements printed with it should not be used in temperatures exceeding 55–60°C. Its major advantage, however, is that the components made of this material can be used as a base while working with special-purpose (e.g. conductive) filaments and that it is biodegradable.
PETG (polyethylene terephthalate glycol)
PETG is a durable and flexible type of filament, fully resistant to water and chemicals. That is why it is often used to print objects such as bottles and other types of packaging. PETG filaments are made in the process of thermoplastic synthesis of such raw materials as terephthalic acid, glycerol and some additional chemical compounds, including antioxidants and stabilisers. A major advantage of this filament is its resistance to chemicals (oils, greases or petrol), hence it is applied very commonly. Its characteristic feature is also its transparency, which matters in a lot of applications.
PA (nylon)
PA is a durable and elastic type of filament, insoluble and resistant to abrasion and mechanical damage. Nylon is often used for printing components that must withstand heavy loads, such as sprocket wheels or extension springs. However, it is worth keeping in mind its hygroscopic properties and protecting oneself against the hazardous fumes it emits during printing. Nylon filaments are made in the thermoplastic synthesis process involving such raw materials as azelaic acid and glycerol, with the addition of antioxidants and stabilisers.
PC (polycarbonate)
This is a type of filament that is resistant to high temperatures and characterised by a high level of durability. PC, also called polycarbonate, is often used to print parts that must withstand high temperatures and loads. PC filaments are made during the thermoplastic synthesis process involving the mixing of such raw materials as bisphenol A and carboxylic acid with chemical additives in the form of antioxidants and stabilisers.
TPE (thermoplastic elastomer) and its variants
TPE is a synthetic material with rubber-like properties that make it remarkably flexible and durable. It should be noted, however, that this is not essentially one type of material, but a wide class of copolymers and polymer blends whose soft and elastic fibres withstand strains that are unattainable for neither ABS nor PLA. TPE filaments are commonly used to manufacture car parts, household appliances and medical products, however, they are not easy to use – TPE is difficult to mould it into the desired shape.
Thermoplastic polyurethane (TPU) is a specific variant of TPE, whose filaments are very popular. Compared to regular TPE, this material is slightly stiffer, which makes printing easier. It is also slightly more durable and better preserves its flexibility at low temperatures. However, just like TPE, it is also a demanding filament to print – it requires a narrow filament path and a low speed of printing in the temperature ranging from 210 to 230°C.
Another TPE variant is a thermoplastic copolyester (TPC). It is not as commonly used, but in some applications it has the advantage of higher resistance to chemicals, UV radiation and temperature, which can reach even up to 150°C without damaging the material.
3D print in prototyping
The importance of 3D printing for prototyping cannot be overestimated nowadays. This technology makes it possible to create fast and inexpensive physical models which shorten the designing and testing phases and make it possible to implement the final version of the item much quicker. By relying on 3D printing, the designers and engineers can create many physical variants of a given item and use them for testing the shape, size and functionality in order to select the best option. It works perfectly e.g. in the automotive industry, where 3D printing is used frequently when designing and creating prototypes for car body components or parts that are installed later inside the cars.
Another example of 3D printing in prototyping is creating medical models, such as prostheses, endoprostheses or surgical tools. Here, too, reducing the time of searching for the final form is very important, and thus the popularity of 3D printers in the medical industry is rapidly increasing. Finally, it’s worth mentioning the prototyping of the injection moulds themselves – here, once again, the use of 3D printing makes it possible to manufacture new plastic products quickly and easily.
There is one more aspect of using 3D printing in prototyping processes – the financial one. Making the prototypes yourself instead of outsourcing them costs much less and at the same time protects better the manufacturer’s intellectual property.
3D printing in electronics
It is obvious that 3D printing has applications in electronic design, too. During CAD/CAM designing, separate programs design PCBs, electrical engineering components and enclosures. Thanks to the fact that the enclosures can be printed immediately, they can be quickly and efficiently designed and modelled until the optimum design is achieved.
The newest solutions give users even more: printing enclosures with electronic circuits embedded in them. This is the result of combining two processes that used to be independent – 3D printing and automatic placement of components on PCBs – with a very interesting solution in the form of a conductive filament. This results in a machine for manufacturing fully functional electronic devices. First, the entire conductive circuit is designed in a suitable environment, and then it is sent to the software that combines it all into a file from which the printer reads information about printing the enclosure, creating conductive connections and the components layout.
3D printing also enables short-run production, custom order production, and the development of components for beta testing. Moreover, it also makes it possible to create spare parts for non-standard devices which are usually quite expensive.
Filaments available in the TME offer
TME offers filaments manufactured by many renowned suppliers and presenting a wide spectrum of materials made of synthetic and natural components. These include such materials as ABS in many variants, i.e. ASA (acrylonitrile styrene acrylate), HIPS (high impact polystyrene), PA (nylon, i.e. polyamide), PCABS (blend of polycarbonate and ABS), PET (polyethylene terephthalate), PLA (polylactide), PMMA (polymethyl methacrylate), PVA (polyvinyl alcohol), SILK (glossy variant of PLA) and thermoplastic elastomers – TPE and TPU. Moreover, there are also filaments from the iglidur® series adapted to specialist industrial applications, based on highly efficient base polymers with the addition of different types of fibres and solid greases. These latter components provide the preferred properties that are required in specific niche applications, for example the necessary durability, resistance or limited friction and wearing off the elements printed with them. Due to that, they will be suitable for e.g. manufacturing bearings.
