Nondestructive evaluation of PLA cubes with varying cooling conditions

Fused Filament Fabrication (FFF) is one of the most extensively used additive manufacturing (AM) methods for the manufacturing of thermoplastic polymers. However, there are still many problems related to the quality of the printed parts. Most of the current research work for improving the part quality is limited to optimizing process parameters and using imaging techniques to analyze the part quality. Due to lack of consistency of quality across printers and printed parts, these efforts are insufficient to characterize and predict local material properties within the parts. Ultrasonic evaluation techniques are becoming increasingly recognized in assessing parts created by AM. In this work, Polylactic Acid (PLA) cubes were printed with varying fan activation layers. Ultrasonic and X-ray CT testing are employed to analyze and detect the controllable and observable deformation due to the change in in-situ cooling condition within the cubes. At the same time, mechanical properties and defect content were evaluated. It is important to understand the relationship between the fan cooling and mechanical properties so that effective fan cooling strategies can be deployed for consistent fabrication of higher quality parts across printers.