Pilot investigation of feedback electronic image generation in electron beam melting and its potential for in-process monitoring

• Published in: Journal of materials processing technology Vol. 266; pp. 502 - 517
• Main Authors: Wong, Hay, Neary, Derek, Shahzad, Sohail, Jones, Eric, Fox, Peter, Sutcliffe, Chris
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2019; Elsevier BV
• Subjects: Additive manufacturing; Aerospace industry; Backscattered electrons; Backscattering; Biocompatibility; Construction materials; Digital imaging; Electron beam melting; Electronic imaging; Image detection; Image processing; In-Process monitoring; Metallic materials; Monitoring; Quality control; Reproducibility; Secondary electrons; Surgical implants; Thermal imaging; Titanium base alloys; Backscattered electrons; Electronic imaging; Metallic materials; In-Process monitoring; Quality control; Additive manufacturing; Electron beam melting; Secondary electrons
• ISSN: 0924-0136; 1873-4774
• DOI: 10.1016/j.jmatprotec.2018.10.016

Electron Beam Melting (EBM) is an additive manufacturing technique increasingly used by many industrial sectors, including the medical and aerospace industries. The application of this technology is, however, challenged by the lack of process monitoring and control systems to monitor process repeatability and component quality reproducibility. Various monitoring systems, mainly involving thermal and optical cameras, have been employed in previous attempts to study the quality of the EBM process. However, these systems have limitations, which include: (1) images generated unavoidably include monitoring-irrelevant regions beyond the processing area and (2) images are subject to keystone distortion. In this paper, a digital electronic imaging system prototype is described for the Arcam A1 EBM machine. This paper aims to: (1) disseminate the prototype design, (2) demonstrate the prototype ability to overcome limitations of the existing thermal and optical imaging systems, (3) showcase the potential for the prototype to serve as an alternative EBM monitoring technique, and (4) serve as a pilot study for future in-process EBM monitoring research with electronic imaging. Digital electronic images were generated by detecting both secondary electrons and backscattered electrons originating from interactions between the machine electron beam and the processing area using specially designed hardware. Prototype capability experiments at room temperature and approximately 320°C were conducted with digital images being generated and analysed from a Ti-6-Al-4V (as demonstrator material) test build. Results suggest that this prototype has significant potential to be used for in-process monitoring of EBM in many manufacturing sectors.