Theoretical Modeling and Experimental Evaluation of Interlayer Wait Time Effects in Thin Wall Geometries for Wire Arc DED

Wire arc directed energy deposition (DED) is a large-scale additive manufacturing process with the advantages of high build rates, large build area, and 6-axis robotic pathing. Using wire arc DED to build a wide range of parts necessitates building thin wall geometries, which can maximize structural strength but pose unique thermal issues during the build process. In these geometries, interlayer wait time has a strong effect on overall heat buildup, geometric anomalies, and columnar grain growth, due to the narrow and strongly directional conduction path down into the baseplate. To predict these effects across the full process space, a theoretical model based on semi-analytical heat transfer modeling and non-dimensionalization was developed. To validate the model, experimental data was collected for a range of interlayer wait times, powers, and travel speeds using the wire arc DED process. This validated model can be used to predict and control heat buildup across a wide range of process inputs in thin wall geometries, enabling more reliable build planning for an important class of DED parts.