Design guidelines for multimaterial parts manufactured in the material extrusion of metals process

Multimaterial additive manufacturing enables the integration of different materials within a single component, allowing for tailored functionality and the reduction of process steps. Among available metal additive manufacturing (AM) techniques, material extrusion of metals (MEX/M) offers a cost-effective and feasible approach for the production of multimaterial parts using a commercial feedstock. This study focuses on the fabrication of green parts composed of pure copper (Cu) and Inconel 718 (IN718), selected for their highly complementary properties: Cu offers excellent thermal conductivity, while IN718 provides outstanding mechanical strength, as well as high corrosion and oxidation resistance. These characteristics make the Cu-IN718 combination particularly attractive for demanding aerospace applications, such as heat exchangers and combustion chambers. A design of experiments approach using response surface methodology was employed to evaluate the influence of key printing parameters, such as nozzle temperature, printing speed, extrusion multiplier, and layer thickness, on the density and dimensional accuracy of green part test specimens. Optimal process parameter sets for each individual material were identified and a corresponding parameter set for the multimaterial combination was subsequently derived. Different geometric features, various material topologies, and two interlocking geometries were analyzed to assess the print quality and geometric accuracy of multimaterial prints. The results were used to derive a set of design guidelines aimed at the manufacturability, reliability, and quality of Cu-IN718 green parts using MEX/M. These guidelines contribute to future standardization efforts in multimaterial extrusion, thus supporting more robust and reproducible production of components via metal AM.