Additive manufacturing (AM) techniques have the potential to produce complex parts, and many of these techniques require the use of support structures to prevent deformations and to minimize thermal effects during the printing process, particularly when building overhangs and internal cavities. However, removing the support structures through postprocessing incurs additional costs and time penalties. Unlike other AM techniques, support structures are not used in directed energy deposition (DED) technique due to its working principle. Therefore, special multiaxis complex path-planning strategies for DED are adopted to print relatively simple overhang geometries. Nevertheless, printing internal channels using this technique can still be challenging or nearly impossible. In this work, a novel DED process using graphite as a support material is proposed for additively manufacturing simple and complex internal channels. The support material is easily removed without requiring extensive machining processes. The results demonstrated that the support material did not negatively impact part quality, and in fact, the presence of different carbides at the interaction zone increased hardness and Young's modulus. Moreover, there were no cracks and or porosity at the support material-part interface. This study is the first of its kind to demonstrate the potential for using graphite as a support material for DED processes in additively manufacturing parts with complex internal channels and overhangs and highlights the need for further research in this area.
Keywords: DED; Inconel 718 alloy; graphite; internal channels; support free.
Copyright 2023, Mary Ann Liebert, Inc., publishers.