New assembly line cleared for take-off

Premium AEROTEC specialises in the design and production of large aircraft components with complex shapes. In addition to shells and structural components, these include entire fuselage sections – such as section 19 for the Airbus A320 family made in the manufacturing workshops in Augsburg.

Since May 2017, the manual assembly steps have been networked with intelligent automation solutions: the partial shells now pass through a production system from KUKA in which they are riveted and pre-assembled to form half-sections. In the future, it will be possible to produce up to 50 sections per month here.

In order to meet demand, Premium AEROTEC is faced with the challenge of increasing production output considerably, while simultaneously reducing manufacturing costs. At the Augsburg plant, where products include fuselage section 19 for the Airbus, the company is therefore using a KUKA system specially developed for the aerospace sector.

“Our goal of supplying up to 575 single-aisle sections annually can only be achieved with automation,” says Dipl.-Ing. Rainer Weber, project manager in assembly location development. “That is why we are installing a modernised partial shell production and longitudinal joint assembly facility for section 19 of the A320 family in our manufacturing shop.”

Transparent production

The centrepiece of the plant is an 80m-long system with three robots and three automatic, all-electric drilling/riveting centres. The entire system was implemented by Augsburg-based robotics and automation specialist, KUKA – in cooperation with subsuppliers, such as Gemcor. The KUKA team – acting in the role of system integrator – invested a good two years in this project together with Premium AEROTEC and other partners, and played a leading role, ensuring that the system was installed and put into operation on time.

Production of section 19 has now been completed using the new assembly line. The worker loads the skin panel into a manual station where it receives an RFID identification chip. On the basis of this chip, the handling robots and riveting centres at the individual stations recognise the component and can change to the corresponding tool, for example. In this way, each component can be tracked seamlessly throughout the entire manufacturing process. Moreover, the component-specific process information generated in the assembly stations is collected, supplemented with other information and then saved in the database.

In the long term, this is intended to minimise the manual inspection and documentation effort involved in the riveting process and replace it with automated documentation. Furthermore, the manufacturing process can be monitored more efficiently. If a process- or quality-relevant value is outside the defined tolerance, the corresponding machines stop.

“We use the performance data not only for documentation and for visualisation of system progress, but also to optimise production sequences,” states Thomas Vogt, head of Shell Assembly. This makes it possible to detect bottlenecks in production, and also to support preventive maintenance, thereby enabling transparent production in keeping with the philosophy of Industry 4.0.

Once the partial shells have been fitted with a chip and the assemblies have been loaded into the component carriers by the worker, automated processing begins. The handling robot on a linear axis picks up the component carrier and hands it over to one of the transfer stations located inside the two riveting stations. Until now, modular pallets made of steel were used as component carriers. Together with the two partial shells mounted on them, this added up to a total weight of more than 1,000kg – too heavy to be moved by jointed-arm robots in the planned cycle production.

In cooperation with Premium AEROTEC, KUKA developed a solution based on weight-reduced aluminium profiles. The result: a lightweight gripper on the robot and a component carrier that now only weighs around 400kg including the partial shell. The industrial robots deployed here – a total of three KUKA KR 1000 titans – can move the load quickly and precisely, thereby considerably reducing manufacturing and assembly costs.

Parallel to the development of the component carrier, trials were conducted to measure the speed and precision with which a robot can position the partial shells on the carrier. The results give an indication of the stiffness of the overall system – this information is important, as the positioning cycle must be completed without significant vibration before a riveting cycle is started in the automated cell.

The automatic drilling/riveting centres are permanently installed in the cell. The stringers, clips and edge supports are joined to the outer skin of the partial shells here. Drilling, countersinking and the setting of rivets are carried out automatically: a machine vision system performs local referencing on the basis of the tacking rivets, then drills the hole and sets the rivet. Rivets of many different lengths and diameters are automatically fed to the system and processed – up to 1,800 per partial shell. The component carrier with component is then transferred to an equipment station. The assembly is manually released from the clamps and transported by an over-head craneway system to the next station, where the partial shells are pre-assembled to half-sections in further component carriers and then transferred to the final drilling/riveting centre on a rail-bound industrial truck. Here the remaining fasteners are set and the half-section is completed.

Controller integration

KUKA integrated the Siemens Sinumerik 840D as the higher-level machine controller. Thanks to the interface between the Siemens controller and the KUKA KR C4 robot controller, workers can operate all machines via a single, familiar user interface. All stations are digitally networked and the overall sequence is controlled by means of a line host PC. Using KUKA’s own control standard – miKUKA – information is collected, visualised on the line and made available to the customer systems. The robot motions for the drilling/riveting process have been programmed entirely by means of offline programming on the basis of Cenit FASTSuite and a specially developed PIK (process-specific implementation kit).

KUKA’s system has enabled Premium AEROTEC to significantly reduce wait times, throughput time and logistics. Arduous manual work steps, such as assembly or manually guided transportation and work at NC machines, have been rendered far more ergonomic – for employees, this means a substantially reduced workload and new work procedures with tasks of greater technical complexity. With this system, KUKA has met the requirements for utmost precision and productivity in conjunction with attractive costs.

“KUKA presented itself as a leading supplier of intelligent automation solutions,” Weber concludes. “With their solution portfolio, combined with our in-depth specialist knowledge in the field of aircraft assembly, we were able to optimise the availability and performance of our production facility and shape it in accordance with the high-quality standards demanded by the aerospace sector.”

The outstanding results of the project are an important building block for the restructuring of the Augsburg shell and section assembly plant. The experiences gained in this project will have long-term benefits: in a further expansion stage, a similar concept is to be implemented with a KUKA automation solution for the assembly of the half-shells to form complete sections.

www.kuka.com