The importance of local process conditions on the properties of fused filament fabrication printed polypropylene components

Abstract

A key characteristic of the manufacture of void free components by 3D printing using fused filament fabrication (FFF) is that this generative process always produces new welded joints between the hot strand leaving the nozzle and the previously deposited and already solidified area. These contact conditions determine the local temperature gradient and the local deformation gradients in the contact. These in turn can have a decisive effect on the morphology and mechanical behavior of the component. In this work, the influence of three different geometric contact conditions under two different machine parameter sets on the morphology and mechanical properties was investigated. The results show that ultimately a parameter simply calculated from the process settings and geometric boundary conditions, the mean contact temperature, is decisive for the properties of the component. If this value is above the melting temperature of the material, quasi-homogeneous morphologies with decent mechanical properties can be achieved in any case. However, if the mean contact temperature is below the melting temperature, the deformation conditions during strand deposition have a significant influence on morphology and properties. The paper describes this behavior using the example of three contact geometries typically encountered in 3D printing with FFF. The discussed correlations between the morphology and the mechanical properties of the printed FFF samples lead to a better understanding of the process and ultimately to the conclusion that the path generation that is, the slicing strategy should take these facts into account in the future in order to be able to exploit the material-intrinsic performance potential in 3D printing as well.