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Smart craftsmanship

Smart craftmanship

At the Böllinger Höfe plant, part of the Four Rings’ site in Neckarsulm, Germany, craftsmanship is melded with smart factory technology to produce the fully electric Audi e-tron GT quattro.

Text: AUDI AG   Photo: AUDI AG Reading Time: 6 min

Two Audi technicians assembling the body, battery, electric motors, and suspension of the Audi e-tron GT inside the production plant. Two Audi technicians assembling the body, battery, electric motors, and suspension of the Audi e-tron GT inside the production plant.

As an employee carefully runs a gloved hand over the exterior paintwork of the fully electric e-tron GT quattro, her gaze follows the movement. The vehicle is illuminated with special lighting that allows Audi experts to spot even the smallest imperfections during the rigorous quality control process. In this case, everything is in order. Once an e-tron GT quattro has passed through the final quality check, it’s ready to leave the Böllinger Höfe premises. This final check is where the paintwork, joints, and gaps are put under the microscope one last time. If needed, fine adjustments are also done by hand at this stage. Before getting to this point, production models must first pass through numerous other stations. The Böllinger Höfe plant at the Audi site in Neckarsulm employs innovative, purpose-built technologies to manufacture the fully electric gran turismo.

Wolfgang Schanz, head of production at Audi Böllinger Höfe, explains, “Producing the Audi e-tron GT quattro—and its body in particular—is a highly automated process. Nevertheless, handiwork is part of every assembly line cycle. The truth is that building a car still calls for craftsmanship. Our colleagues perform this work with great attention to detail.” Experience is another key factor. “We’ve carried over all the handicraft skills built up in manufacturing the Audi R8. What’s more, the same passion our employees invested in building the Audi R8 is now being poured into the Audi e-tron GT quattro.” That’s because the production site for the fully electric GT has been making the Audi R8 since 2014. “Right from the concept phase, the Böllinger Höfe plant was designed as a small-series production facility with innovative and flexible production processes,” says the production manager. “That means the location offers ideal conditions for manufacturing the Audi e-tron GT quattro.” 

In order to accommodate vehicle production for both models at one location, the flexible small-series facility was upgraded and expanded. While retaining the strengths of the Neckarsulm-based Audi facility, integrating the Audi e-tron GT quattro has entailed adding new areas of expertise relating to electrification, automation and digitalization.

Building a car still calls for craftsmanship. Our colleagues perform this work with great attention to detail.

Wolfgang Schanz, head of production at Audi Böllinger Höfe

An Audi technician runs a gloved hand along a newly-built Audi e-tron GT, performing the final paintwork quality check.An Audi technician runs a gloved hand along a newly-built Audi e-tron GT, performing the final paintwork quality check.

The two-way framer and correlation-free measuring

It goes without saying that striving to produce high-quality, precision-engineered vehicles is a top priority at Böllinger Höfe. Every process and every flick of the wrist is performed to this end. The body shop is just one example of the perfectly symbiotic relationship between craftsmanship and cutting-edge technology. A number of different joining methods, ranging from resistance spot welding through screws to rivets and bonding, come into play here. At the heart of the shop is a large clamping and attachment system, known as the two-way framer.

“A framer is used to add large assembly groups to the body, ultimately defining its geometry. Traditionally, two such framers, set up as successive assembly lines, are necessary for body construction. At Böllinger Höfe, we have succeeded in combining these steps into a single station that each car body passes through twice. That’s why it has been dubbed the two-way framer,” explains Christoph Steinbauer, head of the body shop. “On the first pass, the inner side panels are attached; the outer ones on the second. Ten robots with 32 tools are on the job, completing the steps required to join the panels to the car body. They automatically switch tools between the two passes and even during the work steps.”

High-angle shot of a piece of the Audi e-tron GT body inside the crucial two-way framer machine. High-angle shot of a piece of the Audi e-tron GT body inside the crucial two-way framer machine.

Another new station is dedicated to correlation-free measuring—an advance on previous inline measurement procedures. Two robot-guided optical measuring heads check the exact dimensional accuracy of the body at 400 different points. At each point, a blue stripe pattern is simultaneously created and scanned before the robotic arm proceeds to the next one. Room cameras detect and constantly compare the exact location of the measuring heads. This method produces ultra-precise data that allows a rapid response to even the smallest deviations. Following this process, the body assembly line also includes two manual stations. Here, machines pass the baton to humans who weld with great precision by hand. The employees at this station benefit from the experience gained working on the Audi R8. Welders who have spent years crafting the sports car with a V10 combustion engine (Fuel consumption, combined*: 13.6–13 l/100km; CO₂ emissions, combined*: 311–297 g/km) entirely by hand are now well-equipped to work on the Audi e-tron GT quattro.

A robotic arm checks 400 points on the frame of an Audi e-tron GT for dimensial accuracy. A robotic arm checks 400 points on the frame of an Audi e-tron GT for dimensial accuracy.

After the body assembly line, the car-in-progress moves on to the mounting stage. Trained body manufacturers mount the car’s fenders, doors, engine hood, and tailgate. This step focuses on achieving precise, uniform gap dimensions and high-quality surfaces—as even the smallest errors here can result in deviations from the desired standard. This is why the job not only calls for meticulous care and attention but is also best achieved through a return to traditional craftsmanship. A trained carpenter with a keen eye and feel for surfaces is a key part of the team. After the mounting stage is completed, the bodies are ready to be painted.

An Audi technician leaning over the frame of an Audi e-tron GT, using his hands to check for accurate gap dimensions. An Audi technician leaning over the frame of an Audi e-tron GT, using his hands to check for accurate gap dimensions.

Driverless transport vehicles and a newly installed electric overhead conveyor rail system

Freshly painted Audi e-tron GT quattro bodies are briefly stored in a high bay in the basement of Böllinger Höfe. From there, driverless transport vehicles (DTV) carry them to the assembly line on the ground floor. They find their way with the help of a navigation map that includes a digital representation of the surroundings. Two laser scanners at the front and rear sound out the surroundings, ensuring that each DTV knows its exact position at all times. Every day, the 20 smart transport vehicles cover a total distance of around 23 kilometers. Not only do they deliver car bodies for assembly, they also carry them during the first cycles and at the end of the line.

At Böllinger Höfe, the Audi e-tron GT quattro and the Audi R8 are manufactured on the same assembly line. To coordinate this joint production process, the number of cycles has been increased from 16 to 36. The logistics experts in charge of the processes carefully choreograph everything—ensuring that the components for each model arrive in the right place, at the right time, and in the right order. To ensure everything would run smoothly, all assembly procedures were tested in advance using VR technology.

A key element of assembly is the “marriage.” This is when the body of the Audi e-tron GT quattro is combined with the battery, electric motors, and suspension. Resting on workpiece carriers, these major technical modules are moved within millimeters of the correct position below the body via a roller conveyor. With the help of self-positioning power screwdrivers—and employees’ equally precise handiwork—parts are screwed together.

A driverless transport vehicle bringing a partially-built Audi e-tron GT to the assembly line, navigating via laser technology. A driverless transport vehicle bringing a partially-built Audi e-tron GT to the assembly line, navigating via laser technology.
 

Virtual reality and 3D scans

The Audi e-tron GT quattro is the first Audi model whose production was planned entirely without physical prototypes—thanks to a combination of factors such as three-dimensional indoor maps, machine learning processes, and virtual reality. As a result, employees were able to test and optimize all assembly processes in virtual rooms.

 

Planning of assembly sequences was done virtually for the most part.

Wolfgang Schanz, head of production at Audi Böllinger Höfe

Human-robot cooperation and assembly aids from the 3D printer

Even though manual precision and dexterity are of primary importance in assembly, robots help out in this area, too—for example, when fitting the front and rear windscreens. Humans and machines collaborate on this work step without safety barriers separating them. This is referred to as human-robot cooperation (HRC). Workers first place the window onto a fixture with automatically adjustable retainers. They then step aside while the robot applies the adhesive. Next, the employees take over again and fit the window to the body with extreme precision.

The 3D printer also makes life easier. At many stations, specially designed assembly aids help the staff work more ergonomically. Employees at the Böllinger Höfe facility who come up with good ideas for improvement don’t have far to go to put them into action. They simply take their proposal to the in-house 3D printing center. In collaboration with a Berlin start-up, the Audi expert team has developed software that reduces the design time for pre-assembly jigs and fixtures by 80 percent. Usually, all that’s required is a sketch and the printed part is created in a matter of hours. This marks yet another big step forward, as Wolfgang Schanz points out: “We have established a lot of new methods, starting with the planning of assembly sequences, which was done virtually for the most part. In the body shop, we have introduced correlation-free measuring. And the assembly aids from the 3D printer that serve as customized solutions for our employees are already proving to be a great asset.”

By pairing extremely flexible, high-tech production with artisanal workmanship, the Böllinger Höfe plant makes a compelling case for enjoying the best of both worlds—craftsmanship and smart factory technology.

Two Audi technicians performing the final quality check on a range of differently-colored Audi e-tron GTs on the assembly line.Two Audi technicians performing the final quality check on a range of differently-colored Audi e-tron GTs on the assembly line.
 
Rear profile of the Audi e-tron GT.

Discover the Audi e-tron GT

Build and price your very own Audi e-tron GT. Plus, learn more about the equipment it comes with, and which interior and exterior options are available to you.

European model shown. Specifications may vary.

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