Non-destructive evaluation of additively manufactured polymer objects using X-ray interferometry

X-ray interferometry provides a dark-field image, essentially a small-angle X-ray scattering image, of the voids and print defects in an additively manufactured polymer object. The interferometers used were tuned to scattering length 2–5 μm and configured to measure scattering along both vertical and horizontal directions. The samples studied included Stanford Bunnies, fabricated from acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), and a quadratic test object fabricated from PLA. The dark-field projection images show orientation-dependent X-ray scattering which is due to anisotropic voids and gaps at the filament-to-filament interface in these fused deposition modeling additive manufacturing objects. SEM corroborates the existence of gaps between filaments.