Additive Manufacturing (AM) has significantly influenced the Space industry via its ability to reduce production lead times and costs, combine multiple parts numbers, and create component geometries not otherwise possible. However, powder-based AM technologies such as laser powder bed fusion (L-PBF) and laser blown powder directed energy deposition (LP-DED) suffer from surface-related defects (SRD) such as high levels of granular roughness and near-surface porosity. These SRD can lead to cleanliness issues associated with foreign object debris (FOD), non-optimal flow conditions yielding excessive pressure drop on internal channel systems, small orifice/feature inaccuracy, increased heat load, and reduced fatigue life. Additionally, while L-PBF has shown the ability to produce thin wall structures, it generally lacks the scale necessary for manufacturing larger rocket engine components such as nozzles, and L-PBF thin wall structures can suffer from less-than-optimal material properties. Conversely, LP-DED can build much larger structures. However, LP-DED cannot produce thin wall structures within the desired thickness ranges required by many rocket engine components. Lastly, required thermal treatment processes of AM components have the propensity to produce oxide layers that may be undesirable for end use, and when these oxide layers form on non- line-of-sight surfaces, their removal can be very challenging. Thus, there is a need for a post-processing solution to be able to: remove oxide layers and/or granular roughness from internal channel surfaces, correct small orifice (and the like) feature geometry, improve pressure drop performance on internal channels, improve component fatigue life, and controllably (and with process scalability) reduce wall thickness to desired dimensional targets. In this presentation, we will share case studies of its work with NASA MSFC on fuel injectors, combustion chambers, and nozzles displaying both process capability to address these needs and the associated component performance benefits.
Learning Objectives:
- Understand the potential application and benefits of various surface finishing processes to external and internal (channel) surfaces
- Understand potential component design advances that can be considered for AM produced parts in conjunction with appropriate surface finishing (post-processing) processes
- Understand what alloys, printing processes, and component applications have yielded success as a part of NASA's work to advance rocket propulsion component manufacturing
