Bend-Forming: A CNC deformation process for fabricating 3D wireframe structures

• Published in: Additive manufacturing letters Vol. 6; p. 100146
• Main Authors: Bhundiya, Harsh G., Cordero, Zachary C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023; Elsevier
• Subjects: Additive manufacturing; Deformation processing; Path planning; Wireframe structures; Wireframe structures; Deformation processing; Path planning; Additive manufacturing
• ISSN: 2772-3690; 2772-3690
• DOI: 10.1016/j.addlet.2023.100146

•A novel CNC deformation process for fabricating 3D wireframe structures is presented.•The process, termed Bend-Forming, combines CNC wire bending with mechanical joints to construct reticulated structures from a spool of feedstock, with rapid build times compared to other additive manufacturing techniques.•A key component of the process is a path planning framework which uses Euler paths and geometrical computations to convert an arbitrary 3D wireframe structure into fabrication instructions for a CNC wire bender.•The error stack-up of the Bend-Forming process is also analyzed to enable fabrication of precise structures. This paper presents a computer numerical control (CNC) deformation process, termed Bend-Forming, for fabricating 3D wireframe structures. The process relies on the combination of CNC wire bending with mechanical joints to construct reticulated structures from wire feedstock. A key component of the process is a path planning framework which uses Euler paths and geometrical computations to derive fabrication instructions for arbitrary 3D wireframe geometries. We demonstrate the process by fabricating exemplary structures on the order of 1 m, including reticulated columns, shells, and trusses, with rapid build times compared to other additive manufacturing techniques. The structures fabricated herein contain defects which result in residual stress and imperfect geometries. To determine the tolerances needed to fabricate accurate structures, we develop a model of error stack-up for Bend-Forming, using fabrication defects in feed length, bend and rotate angle, and strut curvature. We find that for tetrahedral trusses fabricated with Bend-Forming, defects in feed length and strut curvature have a large effect on the surface precision and stiffness of the truss, respectively, and are thus important tolerances to control to achieve structural performance metrics. Overall, Bend-Forming is a versatile and low-power process that is well suited for a wide-range of applications, from rapid prototyping of wireframe structures to in-space manufacturing.