Audi Q7 Production in Full Swing

Press Release

In all, the body of every Q7 features over 3,400 weld points, conventional weld seams measuring a total length of almost 100 metres, and seams held together by high-performance adhesives with an even greater total length of more than 120 metres. The superstructure and tailgate feature components with laser-joined seams measuring more than six metres in length.

But how does the use of such technologies benefit the customer? The use of laser soldering, for instance, has made it possible to achieve the so-called "zero gap" in the roof of the Q7. Previously, at the point where the a side panel frame and roof meet, there was always a relatively wide gap that was covered by a plastic trim strip, usually painted in the same colour as the body for aesthetic reasons. The zero-gap look of the Q7, on the other hand, gives the impression that it is made from a single piece. This made it possible to implement the car's dynamic design principles. In other words, the premium credentials of the Q7 are evident even in its panelling. Other benefits are that wind noise is reduced, the drag coefficient improved and a very high standard of process reliability achieved.

For the bonded joints, epoxy resin with an enhanced crash performance is deliberately used. Crash-optimised adhesives are now so good that fewer weld points are needed on the body. When the requirements and possibilities of bonding are weighed up, it is the real all-rounder among joining techniques: bonding can be used for joining vastly different materials.

Furthermore, adhesives not only satisfy impressively high strength requirements, but also ensure that joins are tight, provide a degree of soundproofing and protect against corrosion. In combination with other techniques such as spot welding or clinching, the use of such adhesive joins significantly boosts the static and dynamic rigidity of a body, as well as its endurance strength and crash resistance.

Audi is applying a new technique for joining together the side section of the Q7. Plasmatron soldering is used for seams measuring 1.50 metres in total. This is a high-speed joining technique that has similar properties to the established method of laser soldering and gives the vehicle high strength around the join between the outer side section and the corresponding insert on the inside.

Plasmatron soldering is used for manufacturing the left and right side sections of the Audi Q7. This joining technique offers the advantage that it is no longer visible once the fine-seam seal and paint coating have been applied, consequently assuring premium visual quality. And the process in fact costs less than laser soldering.

A technology that is actually more familiar in other areas of life – infrared light – has now been implemented for the first time in its known form in car manufacturing. Infrared light has been used for many years for therapeutic and health treatments. The Q7 project is the first example in car manufacturing where a process known as infrared gelling has been put to universal use.

Sections of a vehicle (doors, bonnet and tailgate) are bonded together in order to achieve the strength that is required for day-to-day operation. The adhesive used must be hardened in order to achieve long-term strength. In the past, this has been done by means of stoving. The production experts adopted a new approach for the Q7, because heating components by means of infrared radiation offers the advantages not only of the light beam's high energy density, but also of "stress-free, localised" heating of the component. This plays a vital part in guaranteeing that the adhesive bonds will remain intact throughout their useful life.

The Q7 bodies are then transported from body manufacturing to the paint shop. There, too, it was necessary to make modifications to the plant – albeit on a less drastic scale – in preparation for the Audi SUV.

320 people work there on a three-shift basis, on various models, including the Q7. Eleven different standard colours, nine of them exclusive to the Audi Q7, are applied to the body panels of the Q7. The number of special paint finishes that can be supplied as custom options is almost limitless.

The painted bodies are finally transformed into the finished Q7 on the assembly line. The entire hall is as large as 21 football pitches. Around 1,000 workers are involved in assembly of the Q7. Separate assembly and testing apparatus for the special equipment and electronics was installed for the Audi SUV. "To ensure that these components are installed expertly, production experts from Ingolstadt and Neckarsulm intensively trained and prepared the workers in Bratislava intensively, and provided support for the production start," explained Heizmann.

Assembly of the Q7 involves 165 separate activities. The workers at each station are supplied with the components they need by means of a very special technique. The materials for each assembly stage are delivered in a "shopping basket" in which the worker will find everything from nuts to seat belts neatly arranged in special inserts.

The trolleys supporting the shopping baskets are filled for each specific vehicle in a central picking zone, then taken from there to the assembly lines by the driverless transport system, which is a kind of miniature freight train. As if guided by an invisible hand, these small trains deliver the required materials in perfect condition at precisely the right moment to precisely the right place, entirely automatically, by following a computer-controlled induction loop concealed beneath the floor.

The advantages of this logistics method are superior process reliability and quality, enhanced productivity, and the reduced distances that the workers need to cover. Working sequences and tasks can thus be broadened and changes to the production range rapidly accommodated.

The clean, neat workplaces that this system allows furthermore reduce the risk of the workers being involved in accidents. Some 400 men and women are responsible for keeping the logistics processes functioning perfectly smoothly.

Just-in-time supplies of components are assured by 25 suppliers located in the immediate vicinity of the plant's perimeter fence. The engines of the Q7, the 3.0 TDI (6-cylinder diesel unit) and the 4.2 FSI (8-cylinder petrol engine), are brought to Bratislava by train from Audi's plant at Györ, in Hungary, just 80 kilometres away.

Following assembly, every finished Q7 passes check point 8, the last stage in the production process. From there, the vehicles are transported 800 metres to the testing and proving course on the factory site. Every Audi SUV is put through a precisely defined range of driving checks there. On the 2.4 kilometre oval asphalt track, speed profiles are driven at speeds of 40, 60, 80 and 120 km/h. The inner section of the circuit consists of profiles on which the resonance behaviour and rigidity of the body and the axles of the Q7 are tested. The circuit includes a disagreeably rough cobbled stretch and pronounced undulations, to check whether all parts are genuinely fitted securely. Finally, in what is known as the ESP bend, the function of the Electronic Stability Program is tested before the Q7 models are loaded onto trains and trucks, ready for shipping to dealers.