Closed-loop control of a directed energy deposition process for repair applications

Additive manufacturing processes of the directed energy deposition family such as laser metal deposition or wire arc additive manufacturing offer great control and improved metallurgical properties over traditional processes such as casting. They are very promising for many industrial applications such as the fabrication of intricate parts with high-performance alloys as well as repair applications. However, these processes are generally very sensitive to process conditions, yet are most often operated in open loop. In this study, a closed-loop controller with a suitable error criteria based on 3D scanning data in-between layers is implemented. It is applied to various repair samples made of 316L stainless steel and Inconel 625 materials. The results show that the controller can compensate for suboptimal operating points and in-process deviations while maintaining satisfactory metallurgical and mechanical properties.