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Does anyone know of any academic research behind 3D printer hot end/liquefier design?

All I’ve found is papers on liquefier dynamics where they model polymer flow and go so far as to compare the influence of nozzle geometry variables on the melt behaviour of the material. Also, I have found some papers on FEA of the heat sink.

Other than that, no development or analysis seems to have been conducted on the hot end. Different nozzle materials and geometries? Different heater block geometries? Different heat break design? Different overall design? The effect of an angled hot end on the shear of polymer flow? Effects of melt zone length?

I understand the principles behind the current design, but it surprises me that no further work has been conducted. Everything seems to always point back to the RepRap design which appears to have only been produced through trial and error to reach a “it’s good enough” phase. Now that design seems to be followed as gospel by everyone else.

Apologies if this question is somewhat broad.

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  • $\begingroup$ I don't think there's much point, since it's easy to calibrate your system. We're not producing parts for rocket ships or brain surgeons,so extreme precision isn't relevant. $\endgroup$ Nov 8 '19 at 15:58
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    $\begingroup$ Hotend design is applied science. Academic sciences usually don't concern a lot about applications. For example, there are academic papers about how suitable (or rather unsuitable) ballistic media are for simulating arrow wounds... where the number of arrow related incidents that need this research is almost nonexistent nowadays. $\endgroup$
    – Trish
    Nov 8 '19 at 16:14
  • $\begingroup$ I think there is a lot of potential for this type of research. For example, while brass hotends are the defacto standard due to superior thermal conductivity, stainless steel has better abrasion resistance, but then suffers from thermal issues. This could easily be researched. Also, chemical interactions between the nozzle tip and different plastics can cause a wider bead and affect resolution. My personal experience is that the shorter the melt zone the better for multiple reasons. $\endgroup$
    – user10489
    Jun 2 at 17:24
  • $\begingroup$ Also, a lot of hot end failures are due to issues with the heatsink and molten plastic backing up into the heatsink and permanently solidifying. Clever design tweaks coupled with solid academic research in any of these areas could easily give an order of magnitude improvement in 3d printer design. $\endgroup$
    – user10489
    Jun 2 at 17:26
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Hot end design is indeed applied science as @Trish said. Its design has a lot of interest and is intriguing, but there are not much into it in terms of academic research. There is a lot of knowledge in RepRap forums and other places where people actually run a lot of trial and error tests.

What might be of interest is the fluid dynamics on the molten plastic in order to calculate a sound model with higher resolution.

Also, academic research on 3D printing moves to Bio printing for example. The hot-end thing is simple mechanics/thermodynamics. Such research is usually done in the private sector IMHO.

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