Additive Manufacturing to develop "All-in-One" Injector Heads

In a propulsion module, tremendous forces develop under extreme conditions. This demands maximum levels of reliability and precision in a small space. The injection head is one of the core elements of the propulsion module, feeding the fuel mixture into the combustion chamber. Its traditional design consists of 248 components, produced and assembled in various manufacturing steps.

The different processing steps, such as casting, brazing, welding, and drilling, result in weak points that can constitute a risk under extreme loads. Moreover, it is a time-consuming and complex process: In the field of injector elements, conventional production requires over 8.000 cross holes to be drilled in copper sleeves that are then precisely screwed to the 122 injector elements in order to mix the hydrogen that streams through them with oxygen.

A glance at these figures clearly shows that, from the perspective of risk one functionally integrated component combining all the elements is an obvious but ambitious goal. This could also release huge economic potential and cut the number of processing steps as well as production time, especially for a Class 1 component. Missions costing hundreds of millions depend on these components. Accordingly, engineers are constantly seeking to develop components of the highest quality, functionality, and robustness while simplifying the manufacturing chain and reducing the number of individual elements.

Thanks to Additive Manufacturing, Ariane Group has succeeded in taking this to a whole new level: The injector head of a rocket engine has been simplified and reduced to what is literally an AiO (All-in-One) design. The results of the new injector head produced using additive manufacturing are extremely impressive: Instead of 248 parts, it consists of just one -with the same functionality- and cutting the required time down to a minimum. The project team chose a heat- and corrosion-resistant nickel-based alloy (IN718) as the material to print the 122 injection nozzles, the base and front plates, and the distribution dome with the corresponding feed pipes for the hydrogen and oxygen fuels as one integrated component. In words of Dr.-Ing. Steffen Beyer, Head of Production Technology – Materials & Processes at Ariane Group, “Only additive manufacturing can combine integrated functionality, lightweight construction, a simpler design, and shorter lead times in a single component.”