Cold sprayed copper rocket nozzle highlights faster, flexible manufacturing of complex geometries

Background

Engineers at the National Manufacturing Institute Scotland (NMIS) have developed a manufacture route to produce copper rocket nozzles, exploring the application of high pressure cold spray as a large scale additive manufacturing process.

The work focused on producing thermally demanding components with integrated internal features, demonstrating how high-rate deposition techniques can reduce lead times, improve material efficiency and allow geometries that are difficult to achieve using conventional manufacturing routes.

While based on a rocket nozzle, the part serves as a proof point for large-scale additive processes in a variety of high integrity applications.  

Challenge      

Manufacturing large copper components with complex internal cooling channels presents significant technical and production challenges. Rocket nozzles are among the most critical and costly components in spacecraft systems, required to operate reliably in extreme environments where temperatures can exceed the melting point of the materials used.

These demands place significant pressure on manufacturing approaches to deliver both performance and precision.

However, traditional production methods are typically slow and labour-intensive, often requiring multiple stages of fabrication and extensive machining. This results in:

• Lead times extending to months rather than days
• High production costs due to slow, specialised fabrication processes
• Size constraints with conventional Powder Bed Fusion (PBF) 3D printing, typically limited to parts only a few metres tall
• Difficulty producing large, complex, curved internal cooling channels
• Limited flexibility to adapt designs or scale production

To address these challenges, the team set out to develop an alternative manufacturing route that could dramatically accelerate production while still meeting the demanding performance requirements of rocket propulsion systems.

What did NMIS do?

Engineers at NMIS developed a hybrid manufacturing approach centred on high pressure cold spray, a high-rate additive process that allows copper to be deposited without melting, avoiding thermal distortion associated with traditional welding‑based processes, and supporting large scale builds.

The copper structure was built up layer by layer using cold spray, building the main nozzle structure quickly through high-rate material deposition.

To create internal cooling channels, aluminium features were incorporated within the structure during the build process. These features were subsequently removed using a controlled chemical dissolution process, selectively eliminating the aluminium while leaving the surrounding copper intact.

This approach enabled the formation of fully enclosed, curved internal channels integrated within the nozzle walls – geometries that would be extremely difficult to manufacture using conventional techniques.

The result is a cost-effective, scalable manufacturing route that combines additive deposition, embedded feature design, and post-processing to deliver a complex, high-performance structure.