Analysis of the material efficiency of high-speed laser directed energy deposition

High-Speed Laser Directed Energy Deposition (HS DED-LB) is an additive manufacturing technology in which the powdered metal material is melted prior to deposition, resulting in significantly higher speeds. Material efficiency is unique to each additive manufacturing process and has a major influence on the environmental impact of the process. The HS DED-LB process differs significantly from other directed energy deposition processes due to the high process speeds and has significantly higher powder losses. Therefore, it is necessary to investigate the material efficiency of this rather novel additive manufacturing technology in order to improve the material efficiency in the future. Based on their origin, powder losses in HS DED-LB can be divided into two categories: Thermal powder losses occur due to vaporization and rebound of powder particles. Kinematic powder losses occur due to the high feed rates of HS DED-LB, which require additional distances in the scan path where the material is deposited but the powder is still being conveyed. Therefore, the material deposition rate depends on the selected process parameters and the scan path based on the part geometry. This paper analyzes the factors that influence material efficiency to gain a fundamental understanding of the interdependencies. Depending on the scan path and process parameters, material efficiencies ranging from 4 % to 67 % were determined, the majority of which was caused by kinematic powder losses. The results provide the basis for optimizing material efficiency and thereby reducing environmental impact.