The classic FDM 3D printing process consists of creating layers by depositing a molten material, usually in the form of a plastic filament. Recently, however, a new way of using this manufacturing technology is emerging, moving from coils to the use of pellets or granules. Pellet 3D printing is a 3D printing method that uses thermoplastics in pellet form to manufacture parts layer by layer. More and more companies are developing machines that work with this type of material, or even solutions that can be adapted to standard 3D printers to make them compatible with pellets.
Plastic granules are granular materials obtained by what is known as pelletizing. In the process, materials, which can be chemicals, plastics, composites, or minerals, are molded into a compressed form of granules. These types of resources are mainly used for injection molding, although, as we have mentioned, they are becoming more and more evident in the world of 3D printing. It turns out that its use in additive manufacturing is somewhat low compared to the number of filament spools in existence today. Although this may seem paradoxical, since the filaments are made of granules, and using the granules directly in the print would save an intermediate step in the whole process.
Pellets and 3D printing
One thing to keep in mind is that beads and filaments require different extruders to suit your printing needs. Unlike filaments, pellet extruders have an integral bowl that gradually absorbs materials and pushes them toward the melting zone. There, the granules are softened to the desired consistency, after which the plastic is ejected through the nozzle and deposited on the printing platform. Although the process may seem a bit more complex compared to filament extrusion, it has a number of really interesting benefits that we will see below.
Regarding the main advantages of 3D printing of pellets, we find a clear reduction in the final cost of the parts due to the low cost of the material and the shorter manufacturing time. In this way we obtain an ideal technology for the production of long series or large parts that otherwise would not be entirely profitable. Another positive point is the reduction of jams during the manufacturing process, since when working with filaments it is a common printing problem that we can find. Finally, additive manufacturing with granules makes it possible to create multicolored pieces by combining plastic granules of different colors in the same tray.
But what is especially interesting when working with granules are the final properties that can be obtained. When using filaments, it is important to know that they do not have exactly the same physical and chemical properties as the raw material. In fact, when we manufacture a filament, the raw materials must be heated, which in turn degrades its properties: the more we heat it, the more significant the degradation. Then we are forced to add additives to reduce this degradation. The result obtained is therefore quite different from the starting material. However, by working with granules from the beginning, there is no need to go through these transformations, allowing users to avoid these degradations and get much closer to the chemical and physical properties of the plastic used in injection molding.
As for the disadvantages, it is worth mentioning that 3D printing of pellets is not as democratized as that of filaments at present, so the development of extruders adapted to these materials can be somewhat difficult to achieve. Also, when creating parts layer by layer, the granules are not connected to each other as in the case of the filament, but are spread out. This makes it less easy to control changes in flow rate, which is necessary for more complex parts.
As we can see, the increasing popularity of 3D printing of granules is encouraging many companies to develop their own manufacturing solutions. An example is the Spanish Tumaker project with its 3D pellet printers adapted to the needs of each user, the American company Titan Robotics also gives users the opportunity to print with pellets on their Atlas printer. Will this new trend spell the end of filament spools? What new players will emerge in the additive manufacturing industry that bet on this technology? Only the future will give the answer. If you’re interested in learning more, be sure to check out our next webinar, “Breaking the Boundaries with Pellet 3D Printing,” taking place on January 25 at 4pm CET (10am EDT). Sign up for free HERE.
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