Ariane 6: Precision that takes off

On July 9, 2024, the time had come: The new Ariane 6 rocket successfully launched from the "spaceport" Kourou in French Guiana and fulfilled its mission to place numerous satellites in orbit for research purposes. ArianeGroup developed the 62-meter-long heavy-lift launch vehicle Ariane 6 on behalf of the European Space Agency (ESA). This secures Europe's independent access to space.

After the first launch, the next Ariane launch vehicle made its way into space in March 2025. For this, it requires more than 140 tons of fuel from hydrogen and oxygen. The bottom and top of the four fuel tanks are formed by so-called dome segments made from an aluminum alloy specially manufactured for this purpose. These dome-shaped components are among the most heavily stressed parts of the rocket and consist of several welded panels. For the components to withstand the high loads during the short flight into space, they must be dimensionally accurate and free from cracks and residual stresses before welding. This is achieved through so-called "peen forming" or shot peening. In this forming process, a component – similar to classic forging – is shaped through intensive bombardment with steel balls of different sizes.

Shot peening is a very demanding process, explains Alexander Hoschka, project manager at MT Aerospace: "The balls are shot precisely and in exactly defined quantities onto the component using compressed air. The art is to control all process parameters such as flow rate, process pressure, ball velocity and nozzle guidance along the workpiece. Since the forming progresses with more targeted blasting, the robots must move the blast away from and back to the workpiece surface within 0.1 seconds." A patented dosing system regulates the flow rates of the balls. It is designed for flow rates up to 30 kg/min and five different ball diameters up to 10 mm can be processed without changeover. It is important to immediately remove broken balls or possibly foreign parts like screws from the process, as they could otherwise lead to irreparable damage to the rocket part.

This special process was developed by MT Aerospace. The technology leader for lightweight structures made from metal and composite materials produces the dome segments in Augsburg, Bavaria. "The system is unique worldwide," reveals Hoschka. "We specifically brought various partners on board for this task." The blast process technology company Sentenso was commissioned to build a test machine to develop the peening process. The data specialist Nebumind used the insights gained to implement sophisticated algorithms for automatic generation of peening programs and to monitor the process. In parallel, the machine builder Freymatic, in close collaboration with MT Aerospace and TBM Automation, developed and built the shot peening system including parts handling.

The automation company TBM Automation was responsible for the heart of the system, the demanding dosing process of the balls. Managing Director Silvester Tribus explains: "We had to ensure that the system always provides the right amount of balls at the right speed in the blast nozzles. Additionally, the balls are reused and must be automatically sorted accordingly." To integrate these and numerous other functions such as the complex transport system, protective mechanisms, removal of defective balls, and the two robots into the system, the company from the Rhine Valley uses various Siemens components. Four Simatic controllers with various peripheral devices are at work in the system. Siwarex measuring and weighing systems precisely monitor the ball quantity. Furthermore, 16 G120 drives, several HMIs, RFID systems and an uninterruptible Sitop power supply ensure smooth operations.

The controllers and robots deliver their data via an OPC-UA connection to an edge computer. This makes all process data of the system available for AI-supported evaluation and program correction. The TBM specialists implemented the automation completely in TIA Portal. "This platform enables comfortable programming, configuration and monitoring of automation systems. It is indispensable from our daily work. We have four certified TIA programmers working for us," says Hubert Mathis, project manager for hardware at TBM. TBM Automation has been among the Siemens Solution Partners since 2012, who have sound expertise and experience in the use of Siemens technologies and products.

The components are thoroughly inspected after their manufacture. To be able to prove their quality seamlessly at any time, a digital twin of each dome segment is stored in the database developed by Nebumind. It contains the measurement data from the countless sensors installed in the machine and provides information about all axis positions of the robots. Should inconsistencies occur during external quality control, all processes can be traced exactly. The large amount of data should also provide valuable information for the development of future product types.

Soon the next Ariane 6 rocket will leave Earth and perform its services in space. Many more space missions are to follow. The demand for rocket launch systems is currently high, both among institutional and commercial customers of MT Aerospace, reveals Hoschka: "We are proud of the successful project that has literally taken off thanks to the innovation-friendly collaboration of all involved parties."