The effect of printing temperature and moisture on tensile properties of 3D printed glass fiber reinforced nylon 6

The Fused Filament Fabrication (FFF) process of polymer-based composites has advanced due to its ability to create intricate forms and geometries while maintaining excellent mechanical qualities. Nylon 6 reinforced by 20% glass fiber filament (PA6GF) has more mechanical strength and wear resistance than standard nylon. However, FFF-based 3D printed composites can suffer from poor bead-to-bead bonding and high void content, reducing their mechanical strength. Therefore, this study aims to investigate how the temperature development and mechanical characteristics of FFF-made PA6 reinforced with chopped glass fibers change depending on crucial process parameters. The study used the D638 ASTM tensile test specimen to determine the ultimate strength of the materials. The researchers conducted experiments using different process parameters such as liquefier temperature, print speed, and bed temperature, while varying moisture content and heat treatment profiles. They compared the mechanical characteristics of neat PA6 and PA6GF and investigated the role of these factors in bonding formation during the FFF process and the following mechanical characteristics of the printed pieces. The results showed that the correct heat treatment profiles significantly improved the strength and modulus of 3D-printed composites. The lower the moisture, the higher the tensile strength, by 17% due to diminished voids in the sample. For a given moisture content, the higher the temperature, the better the tensile strength, by 3%. The fiber reinforcements of the samples gave comparatively higher tensile strength, by 45%, which was an intuitive outcome. This study demonstrates that controlling the process parameters of the FFF process, such as liquefier temperature, print speed, and bed temperature, can significantly affect the mechanical properties of 3D-printed objects. Furthermore, moisture content and heat treatment profiles also play a crucial role in bonding formation and, consequently, the mechanical characteristics of printed pieces. The findings can help optimize the FFF process to produce composites with superior mechanical properties, such as nylon 6 reinforced by glass fiber. The study contributes to advancing the field of 3D printing by identifying the critical factors that affect the mechanical properties of printed composites.