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

A 3d printing of a thin wall is achieved by a fused filament fabrication process. The influence of the printing velocities on the filament morphology is studied using optical microscopy. The strand morphology is approximated to different geometries and compared to experimental data. The oblong cross-section is a good approximation to estimate the strand's height and width. A local temperature is recorded by introducing a thermocouple during the printing of a thin wall. The polymer undergoes successive heating and cooling. Their magnitudes decrease with time while the filament deposition occurs farther from the thermocouple location. A steady-state cooling is observed after an extended period of time due to the surrounding air cooling. The influence of the strand's cross-section area on its cooling kinetics is investigated experimentally. The printing of a thin wall with the same geometry is also numerically computed by solving the heat transfer equation with a finite element method. The thermal conductivity takes into account the porosity of the printed wall. An estimation of the heat transfer coefficients between the wall and the surrounding air is done by comparison with a particular experiment. The numerical computation reproduces very well the amplitudes and the periods of heating and cooling observed experimentally. Moreover, the changes in the morphology of the melted filament show the reliability of the numerical tool to obtain a thermal history in agreement with experimental data.