How Does 3D Printing With Pellets Work?

The classic FDM 3D printing process consists of creating layers by depositing a molten material, usually in the form of plastic filament. Recently, however, a new way to use this manufacturing technology is emerging, moving away from coils to the use of pellets or granules. Pellet 3D printing is a 3D printing method that uses thermoplastics in the form of pellets to manufacture parts layer by layer. More and more companies are developing machines that work with this type of material, or even solutions adaptable to standard 3D printers to make them compatible with pellets.

Plastic pellets are granular materials obtained through what is known as pelletizing. In the process, the materials, which can be chemicals, plastics, composites or minerals, are molded into the compressed form of pellets. These types of resources are mainly used for injection molding, although, as we have mentioned, they are becoming increasingly evident in the world of 3D printing. As it turns out, their use in additive manufacturing is somewhat low compared to the number of filament spools that exist today. Though this may seem paradoxical, since filaments are made from pellets, and using the pellets directly in printing would save an intermediate step in the entire process.

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

Pellets and 3D printing

One thing to keep in mind is that pellets and filaments require different extruders to suit your printing needs. In contrast to filaments, pellet extruders have an integral bowl, which gradually absorbs the materials and pushes them into the melting 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 bit more complex compared to filament extrusion, it has a number of really interesting benefits that we will see below.

As for the main advantages of pellet 3D printing, 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 is a common printing problem that we can find. Finally, additive manufacturing with granules makes it possible to create multicolored parts by combining plastic pellets with different colors in the same tray.

But what is particularly interesting when working with granules is 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 we manufacture a filament, the raw materials needs to be heated which in turn degrades its properties – the more we heat it, the more significant the degradation. We are then obliged to add additives to reduce this degradation. The result obtained is therefore quite different from the starting material. However, by working from the start with granules, there is no need to go through these transformations, allowing users to bypass these degradations and get much closer to the chemical and physical properties of the plastic used in injection molding.

In terms of disadvantages, it is worth mentioning that pellet 3D printing is not as democratized as filaments at present, so the development of extruders adapted to these materials may be somewhat difficult to achieve. In addition, when creating parts layer by layer, the pellets are not connected to each other as in the case of filament, but are dispersed. This makes it less easy to control changes in flow rate, which is necessary for the more complex parts.

Pellets allow for the reduction of costs and manufacturing times

As we can see, the growing popularity of pellet 3D printing is encouraging many companies to develop their own manufacturing solutions. One example is the Spanish project Tumaker with its pellet 3D printers adapted to the needs of each user, American company Titan Robotics also gives users the opportunity to print 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 that bet on this technology? Only the future will provide the answer. If you are interested in learning more, make sure to check out our next webinar, “Breaking Boundaries With Pellet 3D Printing,” which will take place on January 25th at 4PM CET (10AM EDT). Register for free HERE.

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