Embedded Workflow for Functionally Graded Material Fabrication with Multi-material Additive Manufacturing

Multi-Material Additive Manufacturing technologies enable the fabrication of objects consisting of multiple materials. Among them, Material Jetting allows the designer to control the spatial distribution of the selected materials down to the size of microns, making it suitable for Functionally Graded Materials. Despite this great capability, governing the design complexity unleashed by this class of material is still limited to the current computer-aided tools. The paper aims at investigating how a traditional Boundary representation (B-rep) in the CAD domain, which has been conceived for homogeneous materials, can be adapted to integrate heterogeneous object specifications. A workflow to produce heterogeneous objects, with a focus on Functionally Graded Material Objects, is outlined, from the design of the object geometry with a CAD system to the generation of the machine instructions. The procedure to specify the desired material distribution and to generate the voxels has been embedded in a traditional CAD software, allowing the users to define the specifications of the heterogeneous object interacting with the B-rep entities. Once the material distribution has been defined, a solid voxelization is performed on the geometry and the material composition for each voxel is computed. Finally, the object is sliced and a set of images is generated, informing the printer which material should be deposited at the specific position. A case study to check the feasibility of the proposed workflow has been performed: different specimens varying the voxel size and the deposition pattern have been printed.