Effect of Interlayer Temperature Control on Interlayer Strength for Large Format Additive Manufacturing of High Performance Thermoplastics

Abstract

With the increase of printing dimensions inherent to Large Format Additive Manufacturing (LFAM), the main challenge of extrusion-based additive manufacturing processes is also magnified: achieving a high interlayer bond quality. Parts manufactured through this process typically exhibit 50–75% lower mechanical performance in the Z-direction (across layers) with respect to X- and Y-directions. The impact of interlayer temperature control on the interlayer strength of a semi-crystalline polymer printed using LFAM has been evaluated. By using assisted heating during printing, the substrate temperature can be raised to the optimal processing range, allowing for the creation of high-quality bonds between the consecutive layers. In this study, multiple sets of specimens are printed at different interlayer temperatures using neat and carbon fibre reinforced LMPAEK™ material. The interlayer bond strength is evaluated through mechanical testing and microscopy analysis, and compared with in-line measurements of the interlayer temperature. The results of this research demonstrate that active heating enables higher quality interlayer bond compared to unassisted printing, reducing the anisotropy of 3D printed parts.