Effect of Build Orientation on Load Capacity of 3D Printed Parts

Abstract

Fused Deposition Modeling (FDM) is one of the most commonly used 3D printing technologies for creating complex parts from a Computer Aided Design (CAD) model. It is observed that mechanical strength of 3D printed polylactic acid (PLA) parts are affected by various parameters associated with part, process, material and operating conditions. One of the key parameters that influences tensile and flexural strength of 3D printed PLA parts is build orientation. Researchers have investigated the effect of a limited number of build orientations on tensile strength. Moreover, less work has been reported which studies the effect of build orientation on flexural strength. None of the studies modeled tensile load and bending load as a function of thickness and compared tensile loading capacity with flexural loading for different orientations. Therefore, an attempt is made to include a greater number of build orientations that occur during 3D printing of complex PLA parts. Build orientations considered in this study are flat, flat-support, edge, edge-45, upright and upright-45 with three thicknesses i.e., 1.2 mm, 2.0 mm and 2.8 mm. Tensile and flexural tests are performed as per American Society for Testing and Materials (ASTM) standards. Experimental results show that six orientations form two groups i.e., strong orientation group and weak orientation group. PLA appears stronger in tensile loading than bending. Edge orientation is strongest during tensile as well as bending loading whereas upright orientation is weakest in tensile loading and upright-45 orientation is weakest in bending. Force trends, it can be concluded that thickness can be minimized where build orientation belongs to the strong orientation group. Similarly, thickness can be increased where build orientation belongs to the weak orientation group.

Breaking Material Symmetry to Control Mechanical Performance in 3D Printed Objects

“…However, this printing orientation leads in all cases to limited performance. This is confirmed by several studies irrespective of the filament material [31][32][33]. The opposite situation is shown in Figure 10b for samples printed according to the longitudinal orientation.…”

“…As a consequence, this building configuration results in a limited mechanical strength and the instable cracking along the necking occurs substantially causing the ruin of the material (Figure 5b). This leads to a limited performance as observed in several studies, for instance in bending loading configuration when upright position is selected [31], or in tensile configuration leading to the lowest mechanical strength scores [32]. The uniaxial loading is also transferred to the sample edge, which leads to the filament decohesion observed in Figure 5c.…”