Process Monitoring and Inspection Systems in Metal Additive Manufacturing: Status and Applications

One of the most significant barriers to the broad adoption of additive manufacturing (AM) is the qualification of AM produced parts. With the high market competition, quality has become the market differentiator for products and services. To maintain or enhance the quality of the products, manufacturers use two techniques, quality assurance and control. In fact, many researchers characterize the quality assurance and control as the biggest challenge to widespread adoption of AM technologies for metals parts in aerospace industries. One approach to overcome this challenge is to implement in-situ process monitoring and inspection systems to enhance the quality of the printed parts and AM-processes. This has been highlighted by numerous research efforts for the past decade and continues to be identified as a high priority research in the AM-processes. In this paper, we review current process monitoring and control systems for metal AM in Powder Bed Fusion and Directed Energy Deposition systems. And then, possible inspection system configurations for improving the quality of AM printed parts are discussed based on the proposed framework and requirement. A comprehensive real-time inspection method and a closed loop monitoring system are proposed to address the quality control for metal-based AM processes