Tailored granule properties using 3D printed screw geometries in twin screw granulation

Twin screw granulation is becoming increasingly relevant due to its compact size, continuous and robust mode of operation, customizable design, and flexible production capacity. This work describes the experimental study undertaken to understand the dependence of granule properties on the screw element design in a twin screw granulator. A CAD geometry analysis of the free volume in the granulator revealed that there is a direct quantitative correlation between the screw geometry and the maximum size and aspect ratio of the granules obtained using conveying elements. Conveying element geometries with different pitch lengths were 3D printed to generate cost-effective prototypes of the designs. Wet granulation experiments were performed using the 3D printed designs to test the hypothesis that the correlation between the granule shape and maximum granule size and the screw element geometry is predictable a priori. The feasibility of 3D printing method for fabricating new screw element designs is examined. Quality-by-Design strategies and scale-up criteria for twin screw granulation are discussed.