Design and Test of a Miniature Vacuum Chamber for the Comparison of Gas Shielding in Laser-Based Powder Bed Fusion for Additive Manufacturing

Abstract

Laser-based powder bed fusion of metals (PBF-LB/M) is a process by which three-dimensional parts can be built layer by layer through the melting and fusing of metal powders. This technique is known as additive manufacturing (AM), and it provides an exciting alternative to typical methods of subtractive manufacturing, for this technique allows for the creation of lightweight parts with much more complex internal and external geometries with ease, that are also low in residual waste. This makes the technique especially useful for high strength and accuracy applications in aerospace. However, PBF-LB/M is far from perfected, for manufacturing defects are common, even in the best systems publicly and privately available. For this reason, many researchers are interested in this technology such as those in the Arnold lab group, who have recently built a desktop experimental setup for dual-laser PBF of metals. The goal of this project was to evaluate the gas flow subsystem and the corresponding gas shielding effect that it provides by comparison with a miniature vacuum enclosure with a guaranteed gas shielding effect. After a brief literature review, the miniature enclosure and its gas subsystem design process and steps of fabrication were outlined in detail. This was followed by a number of single-layer printing experiments using stainless steel powders with both this new enclosure and the large chamber that came before it. These samples were then analyzed both qualitatively through confocal microscopy and quantitatively with the data gathered from these laser z-scans, followed by conclusions and recommendations moving forward.