Maintaining a proper droplet transfer state in electron beam directed energy deposition via absorbed current-sensed control

Electron beam directed energy deposition (EB-DED) holds immense promise for the fabrication of large, intricate, and high-value metal components. However, with the synchronized nature of material feeding and melting, EB-DED introduces substantial challenges to the stability of the process. This affects both part consistency and repeatability. The droplet transfer process has a crucial part in shaping the stability of EB-DED, with the maintenance of the liquid bridge transfer assuming critical importance in ensuring optimal forming quality. Consequently, we present a cutting-edge closed-loop control system built with absorbed current as a solution to this conundrum. This system harnesses absorbed current signals as the sensory source for droplet transfer states. The droplet transfer state serves as the control objective and the droplet transfer distance acts as the regulated variable. We performed a series of experiments, that corroborated the efficacy of this control system in preserving the desired liquid bridge transfer across diverse scenarios while providing a comprehensive elucidation of its operational principles. By capitalizing on the electron products engendered during the forming process, our control system enabled convenient and reliable monitoring and control of droplet transfer states. The system revealed substantial potential in upholding a well-preserved droplet transfer mode, with significant ramifications for enhancing part consistency and repeatability within EB-DED.