Hand in hand with the Robot
"AutoRep": Fully automated process chain for repairing engine components
Engine components really are masterpieces considering the fact that they have to withstand such different levels of thermal and mechanical stresses during flight operation. Nonetheless – in addition to the usual wear and tear – individual areas of damage such as small cracks can arise, which can only be detected and repaired with considerable overhead in the framework of the engine overhaul. Assisted by the findings of the "AutoInspect" research project, Lufthansa Technik has already succeeded in automating the multi-stage and energy-intensive inspection processes and reducing them to a single process step. Moreover, all of the measurement results achieved can now be reproduced fully and, above all, also used for other partly-automated repair processes.
In the framework of the "AutoRep" follow-on project, Lufthansa Technik has now been able to develop new and innovative production processes and intelligent automation technology. This development should provide support in the future for manual repair processes through the existence of an automated, adaptive process chain. In close cooperation with the Institute of Aircraft Production Technology at the TUHH (IFPT) and the Fraunhofer Institute for Laser Technology (ILT), two robots were developed in this context for milling and welding damaged components. The partner BCT Steuerungs- und DV-Systeme GmbH was responsible for the path planning and data transfer, IBG Technology Hansestadt Lübeck GmbH looked after overall system integration while TRUMPF Laser- und Systemtechnik GmbH devoted itself to the welding aspects of the system integration.
All component damage and deformations are first of all recorded digitally by the AutoInspect automated inspection process by means of robot-controlled optical metrology. The damage data generated is documented automatically in the process and transferred initially to the milling robot for repair and from there to the welding robot. The milling robot then separates out the damaged areas (so-called patches) from the component. A substantial increase in the precision of the milling robot was achieved in the scope of the project. Finally, the laser welding robot performs the repair. In addition to patches, cracks can also be repaired automatically as part of the AutoRep process chain. This means there is no longer any need to prepare the cracks by milling prior to welding.
It became apparent during the research project that highly individual repair steps, which require a particular skill set and occur rarely, can be performed more effectively manually than with a robot. Activities such as applying large-scale patches to combustor components will therefore still be performed by skilled workers in the future. The repair robots on the other hand will be used wherever high process reliability and productivity are required and the burden on employees can be eased from an ergonomic perspective. The automated process chain should be used initially for repairs to combustor components, such as the outer liner of the CFM56-5B/-7B engine types, and then on all engine components with complex geometries that are rotationally symmetric, such as cases, and subsequently also on those that are not rotationally symmetric, such as fan blades.
By implementing the results of the AutoRep research project, Lufthansa Technik succeeded as it were in integrating both robots and employees in the partly automated repair process. Employees are not only relieved of monotonous routine tasks through the use of robots, rather are more closely integrated in areas where a high level of manual skill, creativity and flexibility are required. This means that humans are only doing what they do best in any case, yet remain indispensable as an essential link in the new adaptive process chain.
Thanks to the successful development of an automated adaptive process chain, process times are shorter, productivity is increased and the quality of the repair is further enhanced. Moreover, many other areas of Lufthansa Technik could also benefit from the new automation technology, since all data can essentially also be transferred to other systems and processes and used productively. And the original manufacturers could use the data from the inspection and repair process for their future work. By the time the research project concludes at the end of 2015, the process of industrializing the results, in other words implementing them in operation, should be ready to commence.