Force-based process monitoring in extrusion-based additive manufacturing

Extrusion-based additive manufacturing is one of the most widely used 3D printing technologies. However, achieving reliable results, especially with challenging materials, still requires in-depth process knowledge. Process monitoring and control are key to improving reliability and enabling use in demanding applications. This paper presents a method for measuring forces at the hotend while synchronising force data with the G-code. This enables a novel form of process monitoring and lays the groundwork for force-based process control. The measured force curves are analysed across different time scales, revealing characteristic patterns. Using a specially designed test specimen, the study demonstrates how incorrect print settings, namely extrusion multiplier, printing speed, nozzle temperature, line width, and layer height, affect the acting forces. Multiple metrics are introduced to correlate force data with misconfigured settings and are evaluated for their effectiveness. The impact of incorrect settings on print quality is also examined using surface roughness. Moreover, the results show that hotend force measurement can reliably detect major printing errors such as blobbing, spaghetti errors, and warping. This study provides a foundation for force-based process monitoring and control in extrusion-based additive manufacturing, paving the way for a more reliable and robust printing process.