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Never before in the history of the Audi Group has Audi achieved such a rapid and successful production start up as with its new Audi A3. According to Dr. Jochem Heizmann, Member of the Board of Management (Production) of AUDI AG: “We wanted the new A3 to stand for sportiness, premium value, dynamic road behaviour, progressive design and top-end technology, but to realise this we needed to start elsewhere first – with innovative production methods.” And production of the new A3 is not short of innovations.
AUDI AG has invested several hundred million euros at its Ingolstadt site, setting up an ultra-modern body shop, a completely new press shop and an extensively redesigned assembly area for its compact premium sports model.
Audi began to break new ground from the moment planning on processes and production went ahead. With the aid of a ‘digital factory’, i.e. simulation and assurance of production processes and plant in the virtual world, problem areas were identified many months ahead and dealt with before series production started. The result: No need for expensive and time-consuming modifications in the production plants, noticeably shorter planning times – and right from the start of production, Audi was producing cars to the highest quality standards and ultimately recorded the most rapid and successful production start up in its history.
Only four months into production, Audi was turning out the A3 at maximum capacity, the so-called ‘watershed’ of 680 vehicles per day. “Our approach with the A3 was to take series production very slowly in the first three or four weeks, starting with very low daily output targets. We used this period to optimise the processes and to learn more. Then in the following three months, we rapidly stepped up production quantities,” explained the Audi Board Member in connection with the chosen strategy.
For a car manufacturer such as Audi, the challenge here is to overcome a range of technical hurdles which at first sight seem to be incompatible with each other. For example, developing cars of ever increasing complexity plus the associated production plant in ever shorter times while maintaining the highest production quality from start to finish,. Furthermore, the production start-up of a new model needs to stepped up as quickly as possible, to enable high volume production to dominate the market right from the start, with shorter delivery periods and even better compliance with delivery dates – and with a tight rein kept on costs!
It needs little imagination to realise how all this can be achieved for a premium class vehicle such as the Audi A3 – all that is needed is an ultra-modern, efficient production system. The new A3 production plant in Ingolstadt is a model example of how this strategy can be translated into reality. Heizmann continues: “The main aims in A3 production are quality and productivity. With regard to quality, we intend to reach record rankings in the tough AUDIT checks.”
This is why Audi went ahead with one of the largest construction and investment projects in the Group’s history, on the company’s approximately 80,000 square metre north site in Ingolstadt. The total investment volume for the PAN Project (Production Audi North) amounted to over € 500 million, with some € 200 million spent on the new A3 body shop alone (machinery and buildings) and over € 100 million on the new press shop. Another priority for the PAN project was to renovate the primer coating area (around € 115 million); this structural project incidentally had spin offs for A4 primer coating as well.
The new press shop
Every new Audi A3 begins life as huge rolls of sheet metal in the press shop, also known as coils or tailored blanks. On every production day, the 47 metre long, 500-tonne band cutting unit can turn out 300 tonnes of cut-to-size metal. It performs 32,000 cycles per day at a pressing force of 600 tonnes. Applying 2,000 tonnes of pressing force, a transfer press turns this into reinforcing elements, posts and beams for the new A3. The daily material throughput is 150 tonnes.
The ultra-modern, large-capacity suction press has the most impressive dimensions and performance characteristics. It is a steel monster weighing 4,000 tonnes which is 74 metres long, 25 metres wide and 11 metres high. The whole line weighs some 5,000 tonnes and has a daily capacity of 200 tonnes of material; it can produce up to 10,000 A3 body parts such as doors, flaps and side panels. The pressing force is a hefty 7,300 tonnes, equivalent to the combined weight of 100,000 people. This giant also has to meet huge reliability and precision demands. To illustrate this: you could magnify the size of a Swiss watch to the same scale, but its error tolerance would be nowhere near that required of the press shop.
The A3 press shop produces premium-quality outer shell parts with the speed of a photocopier all around the clock on a three-shift system, operated by a workforce totalling around 150 (50 per shift) – and will do so with the utmost reliability for years. Says Wolfgang Godulla, Head of Production in Ingolstadt: “We have created a technologically and logistically ideal press shop that will satisfy the long-term demands of the future.”
The new Audi A3 body shop
After the press shop, the components move to the body shop, which is also brand new. Three shifts, totalling around 600 men and women plus 450 robots, work in this area, which measures 33,000 square metres. At the heart of the body shop is the communication centre. This round glass and steel construction houses the offices of section heads and representatives of the various specialist areas including for example management and quality assurance, and is in the immediate vicinity of both plant and its employees. This guarantees rapid information feedback and direct eye contact during production.
Audi relies on high-tech machinery, innovative joining technology and modified production processes to achieve the required degree of body rigidity for the new A3. Take the side panel: until now the reinforcing elements were inserted in the side panel, then welded together and to the panel. For the A3, a revolutionary order of events has been adopted. First, a carcass composed of reinforcing elements is built. Only then is the side panel attached. In this way, the connecting nodes remain accessible for a relatively long period.
To improve the rigidity ratings and reduce weight, the number of connection points has also been increased by around 50 percent compared with the vehicle’s predecessor, with almost five times as many laser weld and brazing points. The new A3 has a total laser joint length of 16 metres. In addition, there is some 62 percent high-strength sheet metal in the A3 body. Statistics show that the new A3 has a 33 percent higher static rigidity rating than its predecessor. The dynamic flexural strength and torsional rigidity have gone up by 20 percent. All this contributes to the sports-car driving feel of the new A3.
All these demanding body rigidity and crash resistance standards are met without sacrificing the dynamic outlines of the body, thanks to ultra-modern technology in the body shop. A good example of such technology is the ‘zero gap’ method used along the roof edges of the new A3. Where the side panel frames and the roof meet, there was always a relatively wide joint which for aesthetic reasons was usually camouflaged with a plastic trim strip painted the same colour as the car. In contrast, the new A3 with its new-look joint line is ‘seamlessly beautiful’.
Design and exacting performance standards were combined into a single seamless structure. Even at the sheet-metal stage, the premium character of the A3 is evident. Further high-scoring points: reduced wind noise, a lower drag coefficient (cD) and process reliability of the highest order.
The second use of laser-beam brazing on the A3 is around the tailgate. As with the A4 and A4 Avant, the upper and lower sections of the tailgate are laser-brazed. An innovation in this application is the use in the A3 body shop of a fibre-coupled diode laser, an all-time first in large-scale automobile production. Special features of this laser are low investment and running costs and minimal downtimes.
The A3 substructure production line includes four other laser cells, two for floor pan applications at the front and one each for the rear floor and the substructure. Further laser beam welds can be found around the rear roof flange, sills, side panels and firewall panels.
This too is an innovation in car production: the A3’s front-end module is attached to the bulkhead panels, which are welded to the front side members. This is the first use of a bulkhead panel laser unit in which the side members are shortened precisely to the right measurement and the bulkhead panels welded. The bulkhead plate serves to anchor the front-end module. In a collision, impact forces are directed into the side members.
This method, too, guarantees high accuracy of fit and therefore more design freedom. This is the only way to comply with the exacting design criteria such as the gap dimensions between the bonnet, side panels and front-end of the A3. Reducing the weld flange goes hand in hand with this new technique, and lowers the overall weight.
In order to guarantee consistently high quality standards, the most important functions of all the finished sub-assemblies in the A3 body are subject to 100 percent auditing. To achieve this, 14 in-line measuring stations have been installed. The 10 static measuring units are equipped with 158 sensors. The measuring sensors in the four flexible units are robot-guided to some 180 different measuring points. This facilitates early detection of dimensional deviations in components and prompt corrective action.
This in-line measuring technique also checks the dimensional accuracy of the holes formed for the front-axle connection points. With the aid of this in-line assessment technique, Audi is able to maintain a continuously high standard of front axle fit on each finished A3, thus assuring the new model’s agile and precise sports car driving feeling. In addition to this, customers enjoy low tyre wear and low road-contact noise.
Yet another first for the Audi A3 is the universal use of electric-motor driven welding tongs throughout, at a total of some 4,100 welding points on the body. This is accompanied by significantly improved appearance at the welding points. Around 250 of these welding tongs have been installed on the robots. They work a good 10 percent faster than the conventional pneumatic types and cause less material wear because they are applied more gently to the components.
In addition, the new welding tongs have a self-monitoring feature to detect whether their welding caps are regularly milled and whether they are being applied to the correct component combinations. The new tongs have other advantages in terms of energy costs and frequency of servicing. Noise pollution is reduced by 50 percent. Last but not least, the electric-motor drive makes the cost-intensive 12-bar compressed air system redundant.
A further example of innovation in the A3 body shop is the ‘forming and piercing’ station. As if in response to modern fashion, the compact sports model gets its ‘piercing’ done here. The locating holes for the rear lights and bumpers are formed and punched out. Every car body is measured out and processed individually, which achieves a high standard of joining precision between the side panels, rear lights, bumpers and tailgate and also precise glass and metal interfaces. As well as enhanced freedom of design at the development stage, the minimal gaps, premium driving comfort and wind noise reduction all contribute to greater driving pleasure for the customer.
To realise the premium A3 range of colours, Audi has been operating an ultra-modern paint shop since 1998, which uses water-based pigments for finishing the Audi models. There are a total of 14 standard colours, ranging from Toucan Yellow to Lava Grey, and a wide variety of special paint finishes also to choose from when ordering the new A3. A further € 3.4 million has been invested in modifying the paint shop equipment for the new model.
Seen purely in terms of its dimensions, the new assembly line for the Audi A3 is the same as for its predecessor. However, this area has also been completely renovated at a cost of around € 53 million. The continuous assembly line also has its innovations. To quote just one example, the windows are bonded into position by a fully automated process using laser-controlled robots,. Another fully automatic process is the ‘marriage’ of the driveline components with the body. The ‘petrol station robot’ is also fully automatic and ensures that the tank of each individual vehicle is filled with exactly the right quantity of the correct grade of fuel.
A new electric overhead conveyor system with height-adjustable hangers has been installed. It assures an ergonomically satisfactory work routine at each assembly point. At the end, each fully assembled A3 is placed on the combined ESP and shaker test rig, another worldwide first for Audi initially used for the A4. This not only checks the functionality of the ESP sensors as the whole car is turned and pivoted, but also, with the aid of the integrated shaker-roller rig, performs a final acoustic test to detect creaking or rattling noises. Overall, a total workforce of 1,550 is employed on assembling the A3.
In connection with this policy, Wolfgang Godulla insists: “By continuing production of the A3 model line in Ingolstadt we are demonstrating our commitment to Germany as a production location. Both the A3 and the A4 models are in high-volume production at Ingolstadt, and simply because of its potential production volume and the safeguards this provides for employment, the A3 has a special significance.” This is further emphasised by the fact that in the near future the innovative five-door version of the A3 will be built in Ingolstadt too.
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