Software tool for detection and filling of voids as a part of tool-path strategy development for droplet generating 3D printers

This paper presents a new method for filling the arbitrarily shaped closed contours with identical circles, as a part of the slicing software for droplet-generating 3D printers. 3D printers, as a part of Rapid prototyping technology, offer engineers and designers the possibility of producing models and prototypes layer wise in a fast way and directly from a CAD model. A Rapid prototyping process can be roughly divided into two stages: software and fabrication. The software stage has in turn different phases as well, and one of them is of interest in this paper: the slice filling phase, with the focus on the droplet deposition fabrication technology. Available filling methods typically include one or more boundaries (contours), which are followed by more repetitive boundary lines or zig-zag hatching. While filling the interior, inevitable voids arise. Different filling methods produce different kinds of voids. In the process of building a final part, accumulated layer wise voids result in an undesired uneven surface and brittle final parts. In order to reduce the amount and size of the voids, a study has been conducted and different standard infill methods have been simulated and visualised. As an extension to the standard infill methods, a novel software tool based on Voronoi diagrams that detects and fills the existing voids on each slice has been developed in MATLAB. With our software, we achieved an automatised tool which prevents defects whereat distinct areas are treated individually and a trade off between underfill and overfill is adjustable. In order to test the new detect-and-fill-voids approach we conducted several experiments. Different objects have been printed with and without applying our new approach on the standard infill methods. After measuring the surface roughness and fracture toughness, our new approach and its implementation proved to be very effective.