Processing-Structure-Property Relationships of Polycarbonate Samples Prepared by Fused Filament Fabrication
Lichen Fang, Yishu Yan, Ojaswi Agarwal, Jonathan E. Seppala, Kevin Hemker, Sung Hoon Kang
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 macroscale geometry of printed parts. To obtain a fundamental understanding of these issues, we focused on the interlayer bonding region of Polycarbonate samples prepared by a low-cost open-source FFF 3D printer, and performed full three-dimensional (3D) geometrical characterizations using X-ray micro computed tomography (micro-CT). The results showed large geometry variance depending on different printing conditions, including print speed, layer height, and nozzle temperature. Based on the results, we demonstrated the effects of reducing layer height and increasing nozzle temperature as well as compensating material extrusion rate to improve geometric precision with minimum 0.8% deviation. Moreover, uniaxial tensile and Mode III tear tests results showed that there are linear relations between bonding zone geometry and bonding strength. In addition, from the 3D geometry of the resulting printed part, we could estimate the resulting Youngs modulus, which showed good agreement with the measured value. We envision that our findings can contribute to providing guidelines for the selection of printing parameters to improve or customize printing quality. Our experimental data may also serve as benchmark data for future multi-physics simulation models.