An infrared (IR) camera has been installed in an Arcam A2 Electron Beam Melting (EBM) system for improved layer-by-layer monitoring and feedback control of the EBM build process. Previous work has demonstrated the temperature variations possible during a build (e.g., part/powder bed temperature elevates as build height increases) that have been shown to produce microstructural changes as well as a range of defects that can be detected (e.g., temperature anomalies and porosity). A stabilization of temperature during a build can lead to more uniform microstructure and mechanical properties throughout the fabricated part. Further, full spatial and temporal control of temperature could lead to controlled microstructural architectures in EBM-fabricated parts. An automatic feedback control system was developed to acquire a temperature matrix of the current layer and used as an input to a 'ghost operator' that modifies the necessary parameters (speed function, beam current, melt cycle's post-heating time) for temperature stabilization to minimize microstructural variations.
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