Additive manufacturing based bellows

Metallic bellows are elastic vessels that can be both compressed when pressure is applied to the outer surface of the vessel or extended while under vacuum. In the last years, the European Space Agency had to face a significant number of failures and anomalies affecting mainly Titanium edge-welded bellows, used in critical applications for propulsion as well as cooling systems of spacecraft and scientific satellites, resulting in substantial delays and costs for the impacted programs. The defects leading to failure were observed most of the time on the welded joints of the bellows. This study describes the use of a powder bed fusion technology called selective laser melting to manufacture titanium bellows. SLM is a technology using a laser source to produce a metallic part by melting powder layer by layer. Based on the given specifications and under consideration of the additive manufacturing requirements, the design of the bellows was modified, produced in a layer-by-layer approach using the SLM technology, inspected with CT scan and mechanically tested without any plastic deformations or leakage. Initial consideration about cleaning procedures were made and a development roadmap was defined.