Systems and methods for designing and fabricating contact-free support structures for overhang geometries of parts in powder-bed metal additive manufacturing

Inventors

Chou, Yuag-Shan • Cooper, Kenneth

Assignees

National Aeronautics and Space Administration NASA • University of Alabama at Birmingham UAB

Abstract

Systems and methods are provided for designing and fabricating contact-free support structures for overhang geometries of parts fabricated using electron beam additive manufacturing. One or more layers of un-melted metallic powder are disposed in an elongate gap between an upper horizontal surface of the support structure and a lower surface of the overhang geometry. The powder conducts heat from the overhang geometry to the support structure. The support structure acts as a heat sink to enhance heat transfer and reduce the temperature and severe thermal gradients due to poor thermal conductivity of metallic powders underneath the overhang. Because the support structure is not connected to the part, the support structure can be removed freely without any post-processing step.

Core Innovation

Systems and methods are provided for designing and fabricating contact-free support structures for overhang geometries of parts fabricated using electron beam additive manufacturing (EBAM). One or more layers of un-melted metallic powder are disposed in an elongate gap between an upper horizontal surface of the support structure and a lower surface of the overhang geometry. This un-melted powder conducts heat from the overhang geometry to the support structure, which acts as a heat sink to enhance heat transfer and reduce temperature and severe thermal gradients caused by the poor thermal conductivity of metallic powders underneath the overhang.

The problem being solved relates to defects such as curling that occur in overhang geometries of parts produced using EBAM due to severe thermal gradient cycles causing high thermal stresses and geometric deformation. Existing solutions involve lattice support structures that connect physically to the overhang, requiring laborious post-processing removal steps that degrade surface quality. The invention addresses the need for improved methods to reduce labor and time required for fabrication and to improve part quality by providing a support structure that is not connected to the part and can be removed freely without post-processing.

The invention involves calculating a suitable thickness range for the elongate gap filled with un-melted metallic powder to balance heat conduction against potential fusion of the powder. This includes receiving part and support structure dimensions, calculating expected temperature distributions during fabrication, and performing heat transfer analysis or finite element simulation. The support structure may include vertical portions extending to the build plate to conduct heat, and is fabricated using EBAM or other suitable additive manufacturing techniques. The contact-free support structure improves thermal management without structural bonding to the overhang, facilitating easy removal and enhanced part quality.

Claims Coverage

The patent includes one independent claim concerning an article of manufacture with novel structural and thermal features. The inventive features focus on the spatial configuration of parts and support structures, the presence of an elongate gap filled with un-melted powder, and fabrication processes.

The independent claim covers an article of manufacture featuring a contact-free support structure spatially separated by an elongate gap filled with un-melted metallic powder to enable heat conduction without fusing, including vertical supports for heat transfer, fabricated using electron beam additive manufacturing, suitable for various overhang geometries such as cantilevered or undercut portions.

Stated Advantages

Documented Applications