Support-free hollowing with spheroids and efficient 3D printing utilizing circular printing motions based on Voronoi diagrams

Abstract

Extrusion-based printing frequently requires a hollowing step to remove material from inside of artifacts and subsequently reduce the amount of material, printing time, product weight, energy consumption, and ultimately, the cost. Here, we introduce a novel support-free hollowing method that uses an arrangement of vertically-aligned prolate spheroids. In addition to reducing stress concentration through their inherently smooth boundaries, these spheroids require no additional support structure, when properly designed. Additionally, the resulting spheroidal hollows facilitate the circular printing motion of extruders using G2/G3-codes, which provide three critical advantages compared to the currently popular G1-code-based linear motion: shorter printing time, better printing quality, and smaller tool path file. Here, spheroids are arranged by the Voronoi diagram of 3D ellipsoids and the tool path, including circular printing motions, is produced using the Voronoi diagram of circular 2D disks. The proposed algorithms are implemented as the HollowTron webserver and are freely available from Voronoi Diagram Research Center.