How does 3D printing with pellets work?

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The classic FDM 3D printing process consists of creating layers by depositing a molten material, generally in the form of plastic filament. Recently, however, a new way to use this manufacturing technology is emerging, moving from coils to using pellets or pellets. Pellet 3D printing is a 3D printing method that uses thermoplastics in pellet form to build 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 pellets are granular materials obtained by so-called granulation. In the process, materials, which can be chemicals, plastics, composites or minerals, are molded into compressed pellet form. These types of resources are primarily used for injection molding, although as mentioned they are becoming more and more evident in the world of 3D printing. It turns out that their use in additive manufacturing is somewhat small compared to the number of spools of filament that exist today. Although it might seem counterintuitive, since filaments are made from pellets, and using the pellets directly in the print would save an intermediate step in the whole process.

3D printing pellets

Pellet extruder developed by Tumaker (photo credits: 3Dnatives)

Pellets and 3D printing

One thing to keep in mind is that pellets and filament require different extruders to meet your printing needs. Unlike filament, pellet extruders have a built-in bowl, which gradually absorbs materials and pushes them into the melt zone. There, the pellets 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 little more complex compared to filament extrusion, it has a number of really interesting advantages which we will see below.

As for the main advantages of 3D printing pellets, we see a significant 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 is the reduction in jams during the manufacturing process, as when working with filaments this is a common printing problem that can be found. Finally, additive manufacturing with granules makes it possible to create multicolored parts by combining plastic granules of different colors in the same tray.

But what is particularly 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. Indeed, when manufacturing a filament, the raw material needs to be heated which in turn degrades its properties – the more it is heated, the greater the degradation. It is then necessary to add additives to reduce this degradation. The result obtained is therefore quite different from the starting material. However, by working with pellets from the start, there is no need to go through these transformations, allowing users to circumvent these degradations and come much closer to the chemical and physical properties of the plastic used in injection molding.

In terms of disadvantages, it should be mentioned that 3D printing of pellets is not as democratized as filaments at present, so the development of extruders suitable for these materials can be somewhat difficult to to achieve. In addition, when creating parts layer by layer, the pads are not connected to each other as in the case of filament, but are scattered. This makes it less easy to control flow changes, which is necessary for the most complex parts.

Pellets reduce manufacturing costs and times

As we can see, the growing popularity of pellet 3D printing is encouraging many companies to develop their own manufacturing solutions. An example is the Spanish project Tumaker with its pellet 3D printers adapted to the needs of each user, the American company Titan Robotics also gives users the possibility of printing with pellets on their Atlas printer. Will this new trend mean the end of filament spools? What new players will emerge in the additive manufacturing industry who are banking on this technology? Only the future will provide the answer. If you want to learn more, be sure to check out our upcoming webinar, “Breaking Boundaries With Pellet 3D Printing,” taking place on January 25 at 4:00 p.m. CET (10:00 a.m. EDT). Register for free HERE.

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