Flow analysis of the polymer spreading during extrusion additive manufacturing

Abstract

The spreading of molten polymer between the moving printing head and the substrate in extrusion additive manufacturing is studied. Finite element computation and an analytical model have been used. The hypotheses of the analytical model are qualitatively justified by the results of the numerical computation. The analytical calculation is a powerful tool to rapidly evaluate the relationships between processing parameters (extrusion rate, printing head velocity, gap between the printing head and the substrate) and some characteristics of the deposition (dimensions of the deposited filament, pressure at the printing head nozzle, separating force between substrate and printing head). An isothermal hypothesis is discussed. The viscous non-Newtonian behavior is accounted for through an approximate shear thinning power law model. A printing processing window is defined following several requirements: a continuous deposit, without spreading in front of the printing head, maximum and minimum spreading pressures, an upper-limit for the separating force between head and substrate.

Heating and flow computations of an amorphous polymer in the liquefier of a material extrusion 3D printer

“…This means that the outlet pressure is imposed equal to zero. In real additive manufacturing conditions, the pressure at nozzle exit should be equal to the spreading pressure on the substrate [18]. For the temperature, nothing is applied meaning that θ is unknown right on ∂Ω out .…”

Thermal analysis of the fused filament fabrication printing process: Experimental and numerical investigations

“…The size of the deposited polymer filament is mainly driven by the extrusion velocity U and the nozzle velocity V [5,1]. Fig.…”

The Investigation of Interlaminar Failures Caused by Production Parameters in Case of Additive Manufactured Polymers

“…The 3D printers—in general—are equipped with a 0.4 mm diameter extrusion head, through which the fused material flows upon the previous layer [ 35 ]. The mathematical models that were established by Bellini et al explain the pressure decrease in the extruder head [ 25 , 36 ], on the basis of which the volume of the extruded material was investigated. On this basis, in the case of increased printed speed, the extraction force is growing, and the extruded material’s temperature is decreasing [ 37 ].…”