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A study by the University of Nantes provides revealing results on FDM printing
In the home user area, there is no other 3D printing process that is as widespread as FDM printing. For the industrial area of additive manufacturing, this balance is a bit more mixed, but the FDM process, also known as melt deposition, is one of the most common technologies. It is all the more worthwhile to take a closer look at the research results of a French study. A team from the University of Nantes has investigated how exactly heat transfer and liability work in FDM printing. The aim of the study was to better understand the heat exchange in the FDM printing process and thus to optimize the process.
Poor adhesion as a weakness of FDM printing
The researchers first found that FDM printing offers far more design freedom than injection molding. On the other hand, there is the disadvantage that both porosities in the parts and a bad adhesion between the thermoplastic layers sometimes make for less solid objects.
Searching for the “sweet spot”
Basically, it is important to remember that the adhesion between the layers is mainly determined by the temperature of the nozzle during extrusion. If this temperature is too low, the adhesion is too weak. However, if the temperature is set too high, the polymer will begin to degrade, which in turn can lead to low viscosity and hence structural collapse. In between there is only a narrow corridor for the ideal temperature, the so-called “Sweet Spot”. In order to determine this as precisely as possible, the researchers from Nantes examined the heat transfer in each phase of the process.
Comparison of model and measurements
To do this, the team created a predictive model, the results of which were then compared with a real measurement. A Creality CR-10 was used as the 3D printer, printing was done with ABS and carbon-reinforced PEKK. The researchers carried out the measurements with an infrared camera and a pyrometer. about that heat transfer model The team chose a very simple 3D model as a test pattern because it was very easy to use.
Knowledge of the rheological properties is crucial
As it turned out, the researchers were due to their “poor knowledge of the rheological properties’ unable to accurately predict interlayer adhesion, at least quantitatively. As a next step, the team therefore decided to examine the coalescence development of the polymers more closely in order to be able to predict the formation of macroporosities. Only in this way would the “global degree of adhesion be calculable” and thus provide insight into the process parameters that are necessary for the production of high-performance parts.
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