In Situ Process Monitoring for Additive Manufacturing Through Acoustic Techniques

Additive manufacturing (AM) is an emerging field where a complex geometrical model can be made with no requirement of individual parts and assembly production. This advantage provides the capability for fabricating components in a single integrated process. On the contrary, lack of non-destructive testing adoption due to complex geometries of final products, makes this technology less convenient for the production of critical parts with high accuracy. Non-destructive testing through acoustic techniques is one of the most popular methodologies for AM inspection because of its provision to detect defects on the internal structure of the components. The technique has also been used in other types of fabrication processes (machining and welding) for defect monitoring. There are several studies where acoustic data acquisition and analysis have been done to detect cracks and other anomalies. In this paper, the progress of using acoustic techniques for AM process and part quality monitoring has been reviewed, and critical discussion has been made for the potential application of acoustic techniques toward quality inspection and monitoring in AM technology.