Modeling Bimaterial 3D Printing Using Galvanometer Mirror Scanners

Three-dimensional printing is a process for building new parts with a specified shape. Despite its increasing popularity, printers capable of working with more than one material are yet unavailable. In this work we model the design and the operation of an apparatus for printing with two materials, namely printing a component which includes a previously constructed inner structure. The structure that supports the second material brings difficulties, resulting from the possible "shaded" areas on the printing surface. The problem is addressed assuming the installation of galvanometer mirror scanners as additional light sources on the walls of the printer, and it is modeled in two steps: finding the least number of emitters to use, so that the whole part can be constructed, as well as their position; and assigning them with each cell of the part to be reached. The first step is formulated as a set covering problem. The second is formulated as a linear integer problem and aiming at optimizing two objectives: the number of emitters activated per layer and the quality of the printed part. Methods for solving the problems are described and tested.