Effect of Operating Parameters on the Acoustic Emission Induced by Polymer Surface Shearing in Fused Filament Fabrication

To implement in-process monitoring of 3D printing manufacturing and ensure the quality of printed workpieces, this paper investigates the mechanism of Acoustic Emission (AE) generated from the process of viscous flow shearing during material deposition. Firstly, a flow shearing force equation is derived to consider the dynamic effect caused by wavy surfaces, fluctuating pressures, and rheological properties. Then, deposition distance, material temperature, and flow rate are investigated to correlate the time–frequency characteristics of AE signals with various sources. It has been found deposition distance and material viscosity are two main factors affecting flow shearing behaviors and AE characteristics. At last, experiments were designed and conducted based on the control instructions. The results show an obvious correlation between AE signal and the running parameters, verifying the predictability of the shearing force equation for the main parameters. These findings have paved the foundation for further research on monitoring the extrusion process of additive manufacturing materials using AE technology.