Digital Radiography Tool for Large Additively Manufactured Parts

ABSTRACT This study seeks to demonstrate an optimized inspection method for large am components using digital radiography (DR). The continued improvement of Additive Manufacturing (AM) processes has led to increased part complexity and scale. Processes such as electron beam directed energy deposition process are able to deposit metals at rates upwards of 25 lbs. an hour and produce parts that weigh several hundred pounds. These large structures pose a challenge for current inspection techniques. Typically, computed tomography (CT) is used to create a full, three-dimensional rendering of the part, allowing for internal voids or flaws to be detected. The largest constraints of CT are small scanning volumes and low energies that are not suitable for large parts. This study demonstrates that large scale AM parts can be inspected with relative ease using DR. Whereas CT uses many X-ray images to reconstruct a three dimensional rendering of a part, DR utilizes limited X-ray images. The DR systems parameters and the orientation of the part within the system are then critical to resolution and contrast of the resulting DR image. In this study, unique ray trace and genetic algorithm was developed to provide optimal orientations and inspection requirements for AM components. This information can be leveraged during the design process and post build. By having knowledge of the inspection requirements prior to build, changes in the design can be made to improve inspectability of the component. By utilizing DR post build it will be shown that significant savings in time, cost, and data analysis can be obtained as compared to CT, while providing the same critical information.