Eddy current testing and monitoring in metal additive manufacturing: A review

Abstract

In-situ process monitoring and sensing play an indispensable role in ensuring the quality and repeatability of additively manufactured components, as well as providing a means for optimizing process parameters and increasing the uptime of additive manufacturing (AM) equipment. This review paper offers an overview of the current state-of-the-art in ex-situ and in-situ assessments of AM part quality using the eddy current-based non-destructive testing technique. The adoption of eddy current testing (ECT) for both ex-situ and in-situ AM assessments is still in its infancy. This review paper begins by providing a concise description of the ECT technique and parameters using select case studies on conventionally manufactured components. The implementation of ECT for metal AM part quality assessment is discussed using case studies on powder bed fusion, direct energy deposition, and subtractive/additive hybrid AM components. Additionally, this paper presents the challenges and requirements for further development in this area towards developing closed-loop smart control and AM digital twins. These advancements hold the key to unlocking the full potential of metal AM techniques, thereby enabling more efficient and sustainable manufacturing practices.