NASA Marshall developed a contact-free support structure used to fabricate overhang-type geometries via EBAM. The support structure is used for 3D metal-printed components for the aerospace, automotive, biomedical, and other industries. Current techniques use support structures to address deformation challenges inherent in 3D metal printing; however, these structures (overhangs) are bonded to the component and need to be removed in post-processing using a mechanical tool. This new technology improves the overhang support structure design for components by eliminating associated geometric defects and post-processing requirements.
EBAM technology is capable of making full-density, functional metallic components for numerous engineering applications in industries where high-value, low-volume, custom-designed productions are required. A key challenge in EBAM is overcoming deformation of overhangs that are the result of severe thermal gradients generated by the poor thermal conductivity of metallic powders used in the fabrication process. Conventional support structures address the deformation challenge; however, they are bonded to the component and need to be removed in post-processing using a mechanical tool. This process is laborious, time-consuming, and degrades the surface quality of the product.
The invented support design fabricates a support underneath an overhang by building the support up from the build plate and placing a support surface underneath an overhang with a certain gap (no contact with overhang). The technology deposits one or more layers of unmelted metallic powder in an elongate gap between an upper horizontal surface of the support structure and a lower surface of the overhang geometry. The support structure acts as a heat sink to enhance heat transfer and reduce the temperature and thermal gradients. Because the support structure is not connected to the part, the support structure can be removed freely without any post-processing step.
Future work will compare experimental data with simulation results in order to validate process models as well as to study process parameter effects on the thermal characteristics of the EBAM process.