Identification of Stability Domains for Flow Parameters in Fused Filament Fabrication Using Acoustic Emission

In Fused Filament Fabrication (FFF), the state of material flow significantly influences printing outcomes. However, online monitoring of these micro-physical processes within the extruder remains challenging. The flow state is affected by multiple parameters, with temperature and volumetric flow rate (VFR) being the most critical. The study explores the stable extrusion of flow with a highly sensitive acoustic emission (AE) sensor so that AE signals generated by the friction in the annular region can reflect the flow state more effectively. Nevertheless, the large volume and broad frequency range of the data present processing challenges. This study proposes a method that initially selects short impact signals and then uses the Fast Kurtogram (FK) to identify the frequency with the highest kurtosis for signal filtration. The results indicate that this approach significantly enhances processing speed and improves feature extraction capabilities. By correlating AE characteristics under various parameters with the quality of extruded raster beads, AE can monitor the real-time state of material flow. This study offers a concise and efficient method for monitoring the state of raster beads and demonstrates the potential of online monitoring of the flow states.