Abstract
Electron beam melting (EBM) is a powder bed fusion process capable of manufacturing metallic components out of a variety of alloys. The process is unique in that it relies on the generation of a uniform, densely packed powder bed under vacuum conditions at high temperatures. Therefore, understanding the behavior of the powder subjected to the build environment is crucial to developing the process further.
This study presents a method for comparing the flowability, angle of repose, and packing arrangements of non-virgin Ti-6Al-4V powder under atmospheric and vacuum conditions. The two-dimensional particle packing behavior was acquired during the filling of a container constructed from microscope slides and double-sided adhesive. Data on the Newton or “kissing” number was then analyzed using optical microscopy. To facilitate identical measurements within a vacuum environment, a device was designed to initiate flow within a vacuum chamber using a photoresistor switch and “mechanical finger”. The results show that vacuum environments have negligible effect on powder behavior. These results are important in understanding the connections between benchtop measurements and how they correlate to powder performance within the build chamber. While not explicitly tested, the potential effects that temperature has on powder flow performance will also be discussed.
