Geometrical and Mechanical Characterization of Interlayer Bonding Quality in Fused Filament Fabrication*

Fused filament fabrication (FFF) is one of the most popular additive manufacturing processes. However, advanced applications of FFF are still limited by the large variation of mechanical property and mesoscale structural geometry of printed parts. To develop a fundamental understanding of those issues, we focus on the interlayer bonding region of Polycarbonate FFF samples, and perform full 3D geometrical characterizations using X-ray micro computed tomography (Micro-CT). The result reveals large geometry variance brought by different printing conditions, including parameters like nozzle movement speed and layer thickness, and environmental factors like chamber temperature and humidity. The findings are further validated by mechanical peel/tear tests, showing the direct relationship between bonding zone geometry and bonding strength. The outcomes could guide printing parameter selections, as well as provide validations for future theoretical and simulation models.