Influence of Infill Parameters on the Tensile Mechanical Properties of 3D Printed Parts

Manufacturers that produce products using fused filament fabrication (FFF) 3D printing technologies have control of numerous build parameters. This includes the number of solid layers on the exterior of the product, the percentage of material filling the interior volume, and the many different types of infill patterns used to fill their interior. It is important that manufacturers understand how these choices affect the mechanical properties of the product, the amount of material needed, and how long it will take to print the part. This study tested the hypothesis that as the density of the part increases, the mechanical properties will improve at the expense of build time and the amount of material required. The mechanical strength and stiffness of printed test specimens in this study increased with increasing density. In addition, we found that adding more solid external layers to the specimens increased the strength-to-weight ratio. The ductility was much greater in the specimens with a rectilinear infill pattern possibly due to better pattern alignment of the object and better adhesion to the outer solid layers. This study supported our hypothesis and provides a guide for designers and engineers seeking to optimize tensile mechanical behavior, print time, and material usage for FFF applications through the selection of optimal infill parameters.