Development of a test bench for fused filament fabrication

Current investigations in Fused Filament Fabrication (FFF) only use the typical process parameters to optimize the printed products. Therefore, FFF is not reaching beyond technology readiness level (TRL) 3 for most industrial applications. In order to increase the TRL, detailed process understanding, especially the interactions of process parameters, has to be gained. This paper presents a novel test bench for the detailed analysis of the extrusion process. The setup includes three load cells. This enables the investigation of the interrelationships between process parameters and the material behavior (e.g. pressure) in the melt zone. The investigations include parameter sets at extrusion temperatures between 195 and 230 °C and extrusion velocities between 100 and 600 mm/min. The decrease in feed pressure due to friction in the bowden tube is significant. As expected, with increasing feed speed and/or decreasing extrusion temperature, the counter pressure in the nozzle increases. Measured counter pressures with common PLA as feedstock material are between 1 and 27 N. Next steps are to extend the investigations to high performance materials such as polyether-aryl-ketone (PEAK) and to investigate feed slippage.