Using Computed Tomography to Examine the Interior of a 3D Printer Nozzle

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Explore the Inner Workings of a 3D Printer Using a CT Scanner

Have you ever stopped to think about what’s really happening inside the hotend of your 3D printer? It’s easy to assume that the filament melts and gets pushed out, but is that the whole story? A team of researchers from the University of Stuttgart, led by Marc Kreutzbruck, decided to delve deeper into this process by using a CT scanner to gain a detailed understanding of what’s happening inside the hotend.

To conduct their experiments, the team utilized a Bondtech LGX extruder and an E3D V6 hotend that were mounted to a stationary frame. Instead of relying on traditional X-Y-Z motion control, they focused on measuring the extrusion force using a load cell. Additionally, they used a specialized filament made from high-impact polystyrene (HIPS) mixed with tungsten powder for better X-ray visibility.

The setup was compact enough to fit inside a micro CT scanner, which generated both 360-degree computed tomography images and 2D radiographs. The team made several interesting observations using this experimental setup. The most significant finding was that higher filament speed resulted in less contact area between the nozzle wall and the melt. This was due to the presence of an air gap between the solid filament and the metal of the nozzle. They also noticed that at higher extruder speeds, there was a greater tendency for the incoming filament to buckle, confirming practical experiences.

Furthermore, the researchers discovered that filament speed played a more crucial role in print quality, as measured by extrusion force, than heater temperature. Both factors were important, but optimizing the hot end geometry, specifically through the use of an extended barrel, proved to be the most effective method to achieve sufficient melting time when higher print speeds were desired.

While these findings may not be revolutionary, it is refreshing to see a systematic study conducted on this topic. Many 3D printing enthusiasts often rely on personal observations, so having concrete data to support or debunk certain assumptions adds credibility to the field. Additionally, the CT scanner-generated images provided a unique visual insight into the inner workings of a 3D printer.

Next time you’re watching your 3D printer in action, take a moment to appreciate the complex processes happening within the hotend. Thanks to the work of researchers like Marc Kreutzbruck and his team, we now have a better understanding of the mechanics involved. Who knows what other hidden secrets await us as technology continues to advance!

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