Abstract
Anisotropy of mechanical properties is characteristic of components printed using processes like extrusion deposition additive manufacturing, wherein the properties along the print direction (x-direction) are superior when compared to the corresponding properties in the build direction (z-direction). This effect, influenced by the bond strength in the z-direction, can be more pronounced for components with longer layer times, as the bottom layers tend cool below the glass transition temperature (Tg) of the material, thereby restricting thermal fusion between the printed layers. The work discussed here builds on the previous work by the authors, demonstrating infrared preheating as a technique to actively control the bond temperature during printing to improve the mechanical properties (z-direction) of parts printed on a large-format extrusion AM system. IR preheating was used on the surface of printed layers just prior to the deposition of the next layer to increase the surface temperature closer to the glass transition temperature. The current study explores the effect of variation in bead surface temperatures (indicative of variations in layer times) prior to and after pre-heating on the mechanical properties in z-direction.
