Abstract

Additive manufacturing (AM) is considered as a key technology for the efficient production of individualized components. The technique enables the tool-less production of complex geometries and designs that could not be realized cost-effectively with conventional manufacturing methods. The focus of the presentation is on the Fused Filament Fabrication (FFF), where a thermoplastic filament is extruded trough a nozzle. The material is deposited layer by layer until the final part is build. Thereby, high temperature gradients occur within the part when the hot material is deposited on the lower layers. During the printing process the lower layers are reheated several times so that the material properties are influenced even after the deposition has been made. The thermal history has major effects on crucial material properties such as the degree of crystallization or viscosity. An insufficient viscosity can lead to a weak bonding and reduced strengths between adjacent layers. An inadequate degree of crystallization influences both the structural properties such as the stiffness or the degree of bonding but also the dimensional accuracy due to subsequent shrinkage effects. Additionally, the temperature gradients cause residual stresses which are partly relaxed to varying part deformations. The remaining stresses can lead to premature failures. To achieve a high and repeatable part quality as well as a low scatter in the final part dimension an in-depth process understanding is required considering the underlying material-process-part-interactions. In order to analyze these complex multiphysics processes, manufacturing process simulations are suitable method. A main requirement for the numerical analysis of AM processes is the calculation of the thermal history as accurately as possible. The objective of this work is, therefore, to evaluate the prediction accuracy of currently available AM process simulation tools. For this purpose, an AM process simulation of a cuboid is performed using the Abaqus AM plug-in. The cuboid made of PETG is printed with a Prusa i3 MK3. In order to monitor the temperature history during the printing process very thin thermocouples (0.25mm) are integrated in the center and distributed over the part thickness. The machine code (gcode) is transferred to Abaqus and the transient temperature fields are predicted in dependency on the thermal boundary conditions. The predicted temperatures are compared to the measurements and the prediction accuracy is evaluated.