Reducing the Distortion in Particle Filled Material Extrusion (MEX)-Based Additive Manufacturing (AM) by Means of Modifying the Printing Strategy

This study addresses a ubiquitous challenge in powder metallurgy: sintering distortion. Sintering distortion can have various causes. On one hand, external factors such as friction with the sintering support during sintering or temperature gradients in the furnace, and, on the other hand, internal factors such as anisotropic shrinkage due to directional layer build-up or residual stresses during production, can cause deformation by relieving mechanical stress. This paper presents an approach to reducing residual stresses in components produced by ceramic Fused Filament Fabrication (CerAM FFF) by changing the printing strategy using thermoplastic porcelain filaments with a solid loading of 57% vol. The starting point of the investigation was the torsion of standard sliced porcelain fragments after solvent debinding, which led to the idea to change the printing direction to prevent the distortion. Therefore, a Python™-based post-processor was developed to control the printing direction. It has been shown that this approach can even prevent warpage both for printed ceramic and also for the metal components for technical applications. This simple observation will help all powder metallurgical manufacturers using Material Extrusion (MEX)-based Additive Manufacturing (AM).