New Heights in Measurement precision

Airbus Engineering and Manufacturing are centrally managed, but rely on fully integrated cross-functional and trans-national team working practices, which bring together the capabilities and technical knowledge of 16 different locations in Germany, France, Spain and Great Britain. Every location produces complete aircraft sections, which are subsequently transported for final assembly purposes to Toulouse or Hamburg respectively. In addition to individual components for the German parts of the aircraft, team members at the Bremen factory produce all the necessary landing flaps for Airbus in the structural assembly process. They also prepare the wing assemblies for the A330 and A340 aircraft types. These are very demanding tasks, which demand extremely high levels of precision. To ensure these levels are attained in practice, the Bremen team employs seven Laser Trackers from Leica Geosystems.

Erwin Hoffmann is the leader of the ninemember measurement technology department, whose tasks include examination of large-capacity components, dismantling and removal of production tools, monitoring of examination systems and calibration of all examination systems on-site. He says: “We received our first Tracker in January 1999. Because of the types of problems we were confronted with at the time, in connection with production of the EF200 – the Eurofighter – we needed to acquire either a larger stationary measurement system or a more flexible system. We therefore carried out a comprehensive benchmarking exercise, the result of which was that the Leica Tracker emerged clearly as the best measurement system for us, on the grounds of both speed and cost efficiency. Today, we have three LTD500 Leica Laser Trackers and a further four of the current state-of-the-art Leica Tracker model, the LTD800, in use at Bremen.”

The Leica Laser Tracker is an easily transportable, mobile co-ordinate measurement system. Thanks to the inbuilt laser interferometer, measurements can be carried out rapidly and with high precision. For both single point and surface measurements, the Laser Tracker can record data from a single set-up position on objects with a measurement volume of up to 80 metres diameter, with an accuracy level of +/- 10 ppm (µm/m), at a measurement rate of up to 3,000 points per second. Areas where the Laser Tracker can be employed particularly effectively include high-precision tool manufacturing and geometrical examination in the automobile and aircraft sectors, as well as in other industries. Periodic inspections, repetitive tests and additional tasks can be carried out completely automatically with the help of the integrated absolute distance meter. The set-up procedure for the Laser Tracker is flexible and can easily be adapted to the object size or to confined spatial conditions.

The Leica Tracker plays a crucial role when it comes to mastering the manifold types of problem posed by measurement technology. For instance, new countersinking facilities are dismantled and examined using the Tracker, and collimation of tracks and landing flaps during the preparation of wing assemblies for the long-range aircraft (the A330/A340) is performed using the mobile measurement system. The Trackers are also deployed during the process of putting into operation and approving the entire production system and machinery, as well as during structural assembly at the final examination of all large-capacity components produced at Bremen, and during individual component production.

The Leica Tracker plays a crucial role when it comes to mastering the manifold types of problem posed by measurement technology. For instance, new countersinking facilities are dismantled and examined using the Tracker, and collimation of tracks and landing flaps during the preparation of wing assemblies for the long-range aircraft (the A330/A340) is performed using the mobile measurement system. The Trackers are also deployed during the process of putting into operation and approving the entire production system and machinery, as well as during structural assembly at the final examination of all large-capacity components produced at Bremen, and during individual component production.

A current application example is provided by the equipment used for production of the inner landing flaps of the A320 family of standard-fuselage aircraft. Production is carried out by the Bremen team on behalf of the Stade factory. The team members not only assemble the equipment with the help of the Leica Laser Tracker, but also use it to dismantle everything afterwards. The number of inner landing flaps produced is being increased step by step throughout the course of the year, and production in Stade is due to stop completely at the end of 2005. In the framework of the Ariane 5 space travel programme, the top-level power generators are being measured using the Laser Tracker. The Bremen team has already performed contour measurements and positioned the landing flaps on the Phoenix spacecraft. Geometrical examinations are now performed almost exclusively with the Laser Tracker. The measurement technicians take on nearly all application cases and measurement tasks at the Bremen factory, whilst cause-of-error  investigations also frequently extend the range of applications of the Leica Tracker.

In order to carry out all necessary measurement tasks as well as possible, the Bremen team possesses an extensive palette of accessory equipment for its Laser Tracker. The measurement experts' strategy is to buy each additional piece of equipment once only, but to adapt it in such a way that it can be used in combination with all available trackers belonging to a given model range. The latest example is provided by the recently acquired T-Probe, a unique mobile measurement and examination system (a “Walkaround CMM”), whose software and control system are set up in such a way that they can be used with all four LTD800s on site. The acquisition of the T-Probe occurred against the background of the need to carry out measurements even more rapidly and cost-effectively. Erwin Hoffmann explains: “Until now, for example, we have always measured the landing flaps continuously either from two separate Tracker locations or from a single Tracker location, but with the need for a rotation of the measurement object. However, our goal with the T-Probe is to be able to work with a single set-up, which would bring us further time savings. This is because both the handling of the flaps and the set-up and preparation of the measurement process can be done more rapidly. In addition, the calculation process and the evaluation process become easier and more reliable, because we no longer need to factor in reference points.”

The measurement system is also distinguished by its stability and its minimal maintenance requirements. In addition, the measurement technicians are impressed by its ease of use. This enables a total of 12 team workers in Bremen to carry out the necessary measurement tasks with the Tracker without any problem at all. As well as the seven employees from the measurement technology department, five employees from the production central block also work with the Leica Tracker. The measurement technicians have trained them so that they can work autonomously with the Tracker during the process of setting up and preparing measurement operations. However, the “professionals” then take a final look at their handiwork for purposes of quality assurance; they carry out the final examinations, dismantling and approval. Their colleagues at the Varel and Stade Airbus factories, who have followed the same path, also confirm the wisdom of the Bremen factory's decision to work with the Leica Trackers. What is more, the trust-based co-operative relationship between Airbus and Leica Geosystems is demonstrated by the fact that Leica involved the Bremen team in the development of both the T-Probe and the T-Cam from an early stage.

Erwin Hoffmann concludes: “The Trackers have met our requirements in every conceivable way. As a result, in addition to purchasing the T-Scan, we now also plan to purchase two more Leica Trackers. In the framework of the A400M programme, which gets under way next year, we will have several stations with permanently integrated Tracker systems. Both trackers will be used in the context of quality assurance procedures for the A400M, for examination of interfaces and handoffs, before the fuselage is sent to the final assembly line in Spain.”