Evaluation of the roughness and UTS of 3D-printed nylon with standard and combined structures

Abstract

This study evaluates the ultimate tensile strength (UTS) and surface roughness in 3D-printed Nylon PA66 for three standard infill patterns (starred, concentric, and linear) and two novel combined designs (starred-concentric and starred-linear). Extrusion temperature was considered as a secondary variable (260 °C, 270 °C, and 280 °C), while infill density was kept constant at 80% for all designs. The hybrid patterns increased UTS by up to 50% compared to the conventional ones, demonstrating superior mechanical performance. However, increased strength often coincides with higher roughness, particularly at elevated temperatures, revealing an inverse relationship under certain conditions. In addition, the failure mode varied with temperature; while low temperatures caused premature delamination between layers, a cohesive bond was achieved with the Star-Linear pattern at 280 °C. These findings underscore the importance of pattern design and thermal parameters in optimizing the mechanical and surface properties of printed parts.