Pilot capability evaluation of a feedback electronic imaging system prototype for in-process monitoring in electron beam additive manufacturing

摘要

Electron beam additive manufacturing (EBAM) is an additive manufacturing (AM) technique increasingly used by many industrial sectors, including medical and aerospace industries. The application of this technology is still, however, challenged by many technical barriers. One of the major issues is the lack of process monitoring and control system to monitor process repeatability and component quality reproducibility. Various techniques, mainly involving infrared (IR) and optical cameras, have been employed in previous attempts to study the quality of the EBAM process. However, all attempts lack the flexibility to zoom-in and focus on multiple regions of the processing area. In this paper, a digital electronic imaging system prototype and a piece of macroscopic process quality analysis software are presented. The prototype aims to provide flexibility in magnifications and the selection of fields of view (FOV). The software aims to monitor the EBAM process on a layer-by-layer basis. Digital electronic images were generated by detecting both secondary electrons (SE) and backscattered electrons (BSE) originating from interactions between the machine electron beam and the processing area using specially designed hardware. Prototype capability experiments, software verification and demonstration were conducted at room temperature on the top layer of an EBAM test build. Digital images of different magnifications and FOVs were generated. The upper range of the magnification achieved in the experiments was 95 and the demonstration verified the potential ability of the software to be applied in process monitoring. It is believed that the prototype and software have significant potential to be used for in-process EBAM monitoring in many manufacturing sectors. This study is thought to be the necessary precursor for future work which will establish whether the concept is suited to working under in-process EBAM operating conditions.