Image-driven manufacturing of graded lattices by fused deposition modeling

Lattice structures are receiving a renewed interest in many areas such as biomedical and industrial fields, due to the capabilities of additive manufacturing technologies which allow for the fabrication of very complex shapes. Currently, several methods and tools are described in the scientific literature and some commercial software are introducing dedicated packages to reduce designer efforts for lattice structure design and optimization. However, using commercial CAD/CAM tools in the fabrication of components filled by lattice structure, several critical issues remain and need to be considered. This work aims at manufacturing variable-density lattice structures via fused deposition modeling deriving the density map from a grayscale or colour image. In the proposed approach, the shell-based lattice model is not achieved by CAD tools, but only during the CAM process. In contrast, the lattice relative density is computed by editing the G-code, modifying the extrusion flow according to the local grayscale of a volumetric CAD model, defined from an image. The main advantages are related to the absence of a graded lattice geometric model and the consistency of the toolpath. The method is tested on various images and patterns, and can find applications in artworks, embedded information on components, and functional 3D printed parts, such as the replication of the density map of a bone derived from a DICOM grayscale image.