The sealing of aircraft structures is one of the core processes in aircraft construction, as it ensures the necessary durability and thus the safety of the aircraft for many years. The application of the sealant therefore requires a particularly high degree of accuracy to guarantee absolute quality of the seal. Up to now, this process has been carried out largely manually, which is time-consuming, requires a high degree of quality assurance and slows down production. Sealing is the second most common manual activity in aircraft construction after drilling and riveting.
With the latest development, Broetje-Automation has automated the application of sealants with the highest precision and effectiveness. Robots are used to achieve a consistently high quality of seams and applications. An automated, continuous process monitoring completes the system. The newly developed concept allows savings of up to 20% while improving the quality of the components at the same time.
Due to the high complexity of aircraft components, an industrially mature automation of sealing is a great challenge. Hard to access, curved surfaces and joints must be sealed cleanly and process-safe. At the same time, the sealants used in aviation are often difficult to process, have to be mixed shortly before application and are sometimes very viscous. Nevertheless, the components may only be processed at the precise location provided for this purpose; contamination is not permitted.

In order to be able to meet all these requirements, the sealing concept of Broetje-Automation has a modular structure. Depending on the application, the system can be operated autonomously within a robotic cell or with small, collaborative robots (“CoBots”). The system also provides a “digital twin”, which is integrated into the automated NC programming environment “SOUL OLPS” and can fully simulate the processes. The system is thus optimally prepared for use in the digital factory of the future.

In order to meet the requirements of customers worldwide, the technology team at Broetje-Automation has developed various end-effectors for the application of the material. The system can use polysulfite and epoxy sealants, both using pre-mixed cartridges and with a “mixing-on-the-fly” module that can mix several components live during sealing.
“The many different component types, material mixtures and not least the complexity of the components themselves were a major challenge for us in the industrialization of the system,” explains project manager Dr. Thomas Schwane. “We are proud that after several years of development we have now found a comprehensive solution for the various applications”.

The following types of sealing are already available, for which special nozzles have been individually developed:

• Fillet sealing (e.g. for clips, stringers, frames)
• Cap Sealing (for sealing of rivet heads)
• Epoxy Edge Sealing (for composite components)
• Complex shapes (curves, connections)

The foundations of the technology, which has now been developed to industrial maturity, were laid by research funding within the framework of the Aviation Research Programme (LuFo) of the Federal Ministry of Economics and Energy (BMWI). Broetje-Automation is grateful for this support, without which the current success would not have been possible.