An Analytical Model Experimentally Validated for Density Prediction in Arburg Plastic Freeforming

Arburg Plastic Freeforming combines pellet-based feedstock with droplet-wise deposition, offering material flexibility while posing challenges for achieving full-density repeatability at high printing speeds. An analytical model for part density prediction is proposed here. It is based on process velocity, derived from mass conservation and a tangential droplet-placement assumption, with geometric relationships expressed in terms of the Drop Aspect Ratio and layer thickness. A first campaign on polycarbonate droplet chains enabled us to quantify the deviation between the slicer pixel geometry and the real droplet morphology, thereby identifying a stable parameter set for use in the second experimental activity. Cubic specimens (10×10×10 mm³ ) were printed by varying the tangential speed from 0.05x to 6x, showing close agreement between the extruded and deposited volumes. Density measurements follow the predicted trend where deposition conditions are stable. However, variability in shutter oscillation frequency during high-speed printing alters droplet spacing and undermines consistent full density. Accounting for the measured frequency or propagating its uncertainty within the model restores predictive accuracy and provides practical guidance for process setup and monitoring. The proposed framework reduces trial-and-error and supports future closed-loop strategies to stabilise frequency-velocity coupling, improving reproducibility and enabling wider industrial adoption of Arburg Plastic Freeforming.