Pressure-Based Feedback Control for Reducing Extrusion Pulsation in a Single-Screw Direct-Extrusion 3D Printer

Weight- and cost-optimized extruders are used in additive manufacturing. Material-flow pulsation is a major challenge in screw-based material extrusion additive manufacturing, as it reduces dimensional accuracy and print quality. This study investigates the relationship between internal nozzle pressure and material flow in a polymer-feeding single-screw extruder and evaluates pressure-based closed-loop control as a means of reducing extrusion pulsation. An experimental setup comprising an integrated nozzle-pressure sensor, a synchronized conveyor belt, and a laser-line scanner was developed to simultaneously measure nozzle pressure and the cross-sectional area of the extruded strand. Based on volumetric setpoints derived from the G-code, corrected extruder motor commands were generated and implemented using proportional (P) and proportional–integral (PI) pressure control. The experimental results reveal a strong correlation between internal nozzle pressure and the resulting strand cross-section. The strand modulation correlated with screw rotation could be almost completely eliminated. At the investigated medium extrusion speed, pressure feedback reduced the remaining strand cross-sectional modulation to approximately 33% of the uncontrolled reference condition. Using PLA (Polylactic Acid) material the presented approach demonstrates that pressure-based feedback control is a practical method for improving process stability and extrusion quality in screw-based additive manufacturing and provides a foundation for future advanced control strategies.