Fabrication of Triply Periodic Minimal Surfaces by Wire and Arc-Directed Energy Deposition Based on Thin-Wall Manufacturing Strategy with Overhang in Direction of Surface Extension

Triply periodic minimal surfaces (TPMSs) exhibit excellent mechanical properties. However, their complex geometries impose significant limitations on their fabrication processes. In this study, we fabricate TPMSs using wire and arc-directed energy deposition (DED-Arc) for the first time to leverage its large-scale manufacturing and low production costs. DED-Arc is generally associated with challenges such as distortion caused by high heat input and challenges in fabricating complex geometries. Moreover, TPMS structures feature curved surfaces that include a characteristic overhang in the surface extension direction, i.e., where the width of thin walls increases with height. When fabricating such overhangs, the deposited layers are generally insufficiently tall at the ends of each deposition path. Hence, we propose a novel fabrication strategy incorporating spot deposition, in which localized deposition and cooling are applied repeatedly at the end of each deposition path. Additionally, we devise a method to determine the optimal number of spot depositions based on the overhang angle in the surface extension direction to compensate for the insufficient layer height. Subsequently, we fabricate single- and 27-cell TPMS structures—including Schwarz primitive geometries—using the proposed strategy to evaluate its effectiveness. We evaluate the accuracy of the fabrication process based on X-ray computed tomography measurements, the results of which confirm high geometric fidelity. These findings demonstrate the feasibility of TPMSs fabrication using DED-Arc.