Effect of Abnormal Powder Feeding on Mechanical Properties of Fabricated Part in Directed Energy Deposition

Directed energy deposition (DED) is widely employed in the automotive, aerospace, and defense industries for defect repair and remanufacturing. Stable powder feeding through nozzles for the quality of parts is crucial in the DED process. Detecting changes in the powder flow caused by nozzle defects is visually challenging, and identifying defects in additively manufactured components is equally difficult unless significant distortion occurs. Therefore, prior understanding regarding the quality degradation and development mechanism of process defects associated with abnormal powder feeding is necessary, and product defects must be observed. This research focuses on analyzing the effect of nozzle failure on the shape and mechanical properties of parts. Computational fluid dynamics analysis is performed to examine physical phenomena resulting from an abnormal powder supply. Based on the results, an obstructed nozzle causes an abnormal powder supply, thus resulting in defects in additively manufactured components owing to distortions in the melting-pool flow and temperature distribution.