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

The heating of a polymer in a liquefier of a material extrusion 3D printer is numerically studied. The problem is investigated by solving the mass, momentum, and energy conservation equations. The polymer is taken as a generalized Newtonian fluid with a dynamical viscosity function of shear rate and temperature. The system of equations is solved using a finite element method. The boundary conditions are adapted by comparison with the previous work of Peng et al. [5] showing that the thermal contact between the polymer and the liquefier is very well established. The limiting printing conditions are studied by determining the length over which the polymer temperature is below the glass transition temperature. This provides a simple relation for the inlet velocity as a function of the working parameters and the polymer properties.