Audi Starts Production of the New A6 Limousine
Text and pictures courtesy of Audi AG
"The Audi A6 is a key factor for Audi and the Neckarsulm plant," declared Member of the Board for Production Dr. Jochem Heizmann on the occasion of the production start of the new A6 limousine. He explained that Audi has invested some 530 million Euro in the new product and the corresponding plant infrastructure, adding that the new A6 also redefines the benchmark in respect of production quality - for example through an ultramodern body shop. "We anticipate building over 80,000 units of the new A6 this year," continued Heizmann.
The new A6, the sixth generation of this car line, went into production at Neckarsulm a matter of weeks before the international launch at the Geneva Motor Show and some two and a half months before going on sale to the public. This sporty executive limousine sets new standards in the medium luxury category thanks to its out-and-out drivability, new high-performance engines and countless new features, such as the MMI Multi Media Interface operating concept.
"The Neckarsulm plant has been preparing intensively for the launch of the new model for around two and a half years," remarked Plant Manager Otto Lindner. Approximately 60 percent of the Neckarsulm workforce are involved in A6 production or in directly associated tasks. A comprehensive training programme for the workers established the optimum basis for the production launch. The first pre-production vehicles were built very early on with the new production facilities. The workers were familiarised with the new technology through specialised courses and hands-on training in the production zones. The focal topics were the plant control system, electrics/electronics and suspension.
"We are convinced that we will captivate our customers with this new model, and thus help to safeguard jobs over the next few years," remarked Works Council Chairman Norbert Rank during the flanking programme for the launch, which served to provide 9,000 workers with more detailed information on the new A6 in around 120 separate events.
"The time available for planning within the product development process is getting shorter, while products are becoming more complex," explained Neckarsulm Head of Planning Albrecht Reimold. To keep all planning processes as clear as possible, the body manufacturing and assembly processes were represented virtually within the model. 3D representations boosted planning reliability in the press shop. Familiarisation time on the production presses and design costs were thus reduced, and throughput times for tool manufacturing cut.
Press shop investment
Audi has invested 140 million Euro in the tools for manufacturing the body panels alone. The Neckarsulm press shop manufactures predominantly the large-area outer panel sections for the new A6. A four-stage production process is being used for the first time for the door outer skin.
Innovations in A6 body shop
"The new A6 has a new body concept affording substantially improved standards of rigidity, comfort and safety. The requirements regarding design and body accuracy have become much more exacting," emphasises Wilhelm Stein, Head of A6 Body Shop.
Audi has invested 80 million Euro in a new building and 180 million Euro in new body manufacturing facilities. "The use of even stronger steels, the composite design comprising steel and aluminium and the increasing use of spot weldbonding are placing tougher demands on the plant technology," adds Stein. The degree of automation in the new body manufacturing line has reached around 95 percent. There are around 600 robots in use, whereas the total on the previous model was 450.
The use of aluminium (for the front lid, wings and various interior components) and high-strength steels including stainless steel, coupled with increased use of tailored blanks, has led to a reduction in the body weight of around 30 kilograms.
The joining techniques implemented include traditional resistance spot welding, punch-riveting, clinching, spot weldbonding, laser welding, laser brazing and MIG brazing. The combination of these varied joining techniques produces a high level of crash safety in the new Audi A6, optimum natural frequency behaviour and high body rigidity.
Stainless steel has been used in body manufacturing for the first time on the A6. 31 robots arranged in nine production cells apply a total of 223 stainless steel weld points. The method of inline testing has been introduced to verify the effectiveness of the stainless steel weld points.
The use of a hybrid roof frame is a further highlight of the new A6 body shop. This concept weighs around 300 grams less than the conventional sandwich-design sheet metal structure and consists of fewer components.
The new body shop covers an area of 33,000 m2, equivalent to approximately six football pitches. The A6 body shop is manned by 1,100 workers spread over three shifts.
New features of paint shop
"AUDI AG has spent some nine million Euro on conversion measures to the painting facilities," explains Jürgen Krämer, Head of the Neckarsulm paint shop. A pretreatment line has for instance been converted for treating composite aluminium and steel structures. The automated sill PVC application system and a new wax-flooding device are new. A total of 15 different colours are used. Audi uses exclusively water-soluble paints.
There are some 1,450 workers operating the entire paint shop on a three-shift basis. They paint the Audi A2, A6, A6 Avant, allroad, RS 6, A8, A8 L, Audi TT and Lamborghini Gallardo.
Innovations on the A6 assembly line
Audi invested over 40 million Euro in new plant technology for the A6 assembly line. "In response to the innovations in the field of electrics/electronics, the testing processes have been restructured," reports Peter Grams, Head of A6 Assembly. Extensive tests and adjustments are performed on every vehicle in the new testing areas.
Further highlights of the production line: the front-end module with the new singleframe radiator grille is installed with the aid of a pneumatically assisted handling device. Installation of the driving area is semi-automated, and the windows of the new A6 are likewise fitted by robot. To achieve optimum handling and a very high degree of reliability, fully automatic screwing stations are used. These monitor and log the torques of safety-relevant screw connections online.
There are 3,750 workers manning the A6 assembly line on a three-shift basis. The production area covers around 77,000 m².
New departures in logistics
"The major logistical challenge we are currently facing is how to build the new model alongside the predecessor-based A6 Avant, allroad quattro and RS 6, the latter being built on behalf of quattro GmbH", remarks Steffen Potrafke, Head of Plant Logistics at Neckarsulm. New materials supply concepts assure a smooth flow of materials, production supplies from a single source and optimum utilisation of warehouse space. A large proportion of components are brought in from suppliers on the nearby industrial parks. All items destined for the A6 model are picked in sequence in a new hall at the Bad Friedrichshall Commercial and Industry Park (GIF). This makes optimum use of synergy potential and creates maximum flexibility.
Systematic environmental protection
"The plant has been pursuing a systematic environmental management policy for quite some years. Environmental protection is consequently a high priority in every area of production of the new A6," explains Environmental Officer Bernd Martin.
For example, all the metal trimmings that arise in the press shop are separated and reprocessed. The use of a 'thixotropic' drawing oil, which only starts to flow more readily under the influence of pressure, virtually eliminates oil contamination on the presses and on the floor of the hall.
Spray losses are kept to a minimum in the paint shop. Exhaust air from the paint dryers is burned retrospectively and this heat recovered by means of heat exchangers, so that it can be used for heating purposes. No chromium or lead are used in body pretreatment processes. Fresh air entering the premises is heated up via heat wheels using the heat in the exhaust air from the halls and plant, thus saving a considerable amount of energy. There are closed water circuits in the paint shop and the leak-testing booths on the assembly lines. Returnable packaging for bought-in parts is used wherever possible in the assembly process.