Feedforward compensation to improve extrusion accuracy in progressive cavity pump-based additive manufacturing

Extrusion accuracy is essential in extrusion-based additive manufacturing because it governs filament-width gradients and multi-material patterning, which can tune permeability and mechanical performance in hydrogel constructs. In progressive cavity pump (PCP) systems, volumetric efficiency is reduced during steady extrusion by leakage through the rotor -stator clearance, while flow is delayed during start-stop events by pressure build-up and compliance in the pump-nozzle system. These effects decouple commanded and delivered flow rates and increase printing errors. A moving-mesh computational fluid dynamics model of a PCP was developed, and reduced-order models were derived to predict steady-state output flow and transient response lag. The models were embedded in a dynamic feedforward compensation strategy (DFCS), through which G-code was augmented with inlet-pressure and rotor-speed commands. Continuous filament-width gradients from 100 to 600 μm were enabled by steady-state compensation, while start -stop deposition in dot arrays was improved by transient compensation, yielding area-based deposition errors of 14–24%. Overall, PCP flow dynamics are linked to executable toolpath commands through DFCS, thereby improving gradient printing and start-stop-intensive hydrogel printing.