CFD Analysis on Extrusion of Slurry in Direct Ink Writing

Abstract

Direct ink writing (DIW) is one of the additive manufacturing (AM) technologies being widely utilized to produce functional parts from a complex three-dimensional (3D) computer-aided design (CAD) model without the need of dies, molds, jigs, fixtures and other expensive tools. Recently, screw-type extruder become very vital to handle high viscosity slurry and uniform dispersion of material from the micronozzle for achieving high-dimensional accuracy is extremely essential to fabricate parts using DIW. In this article, computational fluid dynamic (CFD) analysis is performed to simulate the extrusion behavior of the slurry having viscosity in the order of 50,000 poise. Through varying the inlet velocity of slurry for various viscosities, CFD analysis is carried out to determine the maximum pressure developed at the top of feed zone. In addition, extrusion behavior is studied for the cases of increase in the speed of screw spindle and varying mass flow rate. Experiments are performed to measure the viscosity of the slurry with respect to shear rate. Theoretical calculations are compared with CFD analysis results and they are in good agreement in predicting the inlet pressure.