How well can a recycled filament perform?

We tested the printing performances of a filament extruded from waste plastic materials originated from the printing process: a perfect example of a circular economy. Here’s how it went.


Turning 3D printing waste into new filament that can be reused is certainly a valuable example of circular economy. But what does it means exactly?

Circular Economy

According to the Ellen MacArthur Foundation, circular economy is based on the principles of designing out waste and pollution, keeping products and materials in use, and regenerating natural systems.

The FDM technology of modern 3D printers makes it possible to transform raw materials into finished plastic products with almost no waste material generated in the process. Furthermore, after printing it is possible to regenerate the finished product and turn it into new raw material: this is the main reason that led us to create Felfil System. A filament extruder, in fact, allows to create new filament starting from waste plastics (or virgin pellets).

A perfect example of a circular economy!

But we have always been very curious, and the raw theory wasn’t enough. We have been wondering how many times it is possible to repeat the extrusion cycle (filament – finished product – new filament) before the polymer’s performance start to degrade.

How does a recycled filament behave?

Hence, in the past weeks we partnered with another Italian company, MaCh3D, in order to launch an experimental study to understand how PETG changes in its first two life cycles. We wanted to track the mechanical characteristics of both the virgin filament and the material after it is printed through FDM technology.

We compared two different filaments:

  • one extruded entirely from commercial virgin pellets, dried at 60 ° C for seven hours and then extruded with the addition of 2% black universal masterbatch;
  • and another extruded from the printing waste chopped into granules of about 8 mm.


For the extrusion, in both cases we used Felfil Evo at 215 ° C and with a screw speed of 9 rpm and 1.25 m / min, which produced a filament with a diameter of 1.75 ± 0.07 mm.

For the test we used two printers: a Prusa MK3 and a Witbox 1. The mechanical properties of the materials were analyzed on tests produced with horizontal and vertical orientation (left and right in the graph). The data refers to an average of the measured results. In orange the recycled material, in gray the pellets.



As we can see from the graph, the mechanical characteristics of the filament extruded from plastic waste are only slightly lower than those of the filament extruded from the pellet. If limited to a few cycles, the recycled material guarantees proper performances.

Current results seem to show that additive manufacturing and regenerated plastics represent a combination capable of fully satisfying the principles of the circular economy… and providing a perfectly reusable filament. In the coming months the study will be further investigated, and a paper with the test results will be drawn up.

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