Efficient automotive production with RFID technology

Production of the Audi A8 in Neckarsulm: Continuous wireless

It all starts with a piece of metal. In the body shop, the rear part of
the vehicle represents the first stage in creating a customer’s specific order.
Step by step, the car at long last starts to take shape. Once it has spent some
time in the paint shop, this is the point at which even those without much
interest in cars can see the individual notes that have been added – a fiery
red, a deep black, or perhaps even a midnight blue. But even when it isn’t
being given a striking paint job, the new Audi A8 can be manufactured in
numerous customizable designs to make any customer’s wishes come true.

There is admittedly a long road to travel between the
body shop and the new car’s first outing. Checks are required at many points
along the way to ensure that the car is being produced exactly as the customer
had intended upon ordering. In the German city of Neckarsulm, Audi is solving
this task with the help of an RFID-based identification solution that covers
all the types of tasks being carried out at its plant. On the production line
of the successor model to the Audi A8, launched in 2017, UHF RFID read/write
devices from the sensor manufacturer SICK are hard at work. These devices
reliably identify passive RFID labels on the vehicles at every step of the
production process.

Identification with maximum availability…

“Whenever we design a new production line, we
naturally think about the best ways of identifying workpieces at the individual
stations”, says Jan-Erik Butt, who is responsible for RFID technology at Audi
in Neckarsulm. “What we really want to achieve is an identification solution
that takes in every area of the plant – from the body shop to the paint shop
and all the way through to the final assembly area. The durability of RFID
technology makes it ideally suited to this task. It also offers versatile
connection options and can be flexibly integrated into the production system.”

To compare the performance of different suppliers,
Audi conducted tests in its paint shop for a whole week. It is in this location
that the RFID label on the vehicle is subjected to the highest levels of
stress. “SICK was the clear winner when it came to reliability. We require 100
percent availability – in the automotive industry, not even 90 percent is good
enough for us”, emphasizes Thomas Vogel, the specialist project manager in
charge of digital manufacturing for the A8 model range.

…and in challenging environments

During the production process, the vehicles are
exposed to strong external influences such as extreme heat and chemicals.
Circulating air temperatures in the paint shop reach up to 230 degrees, and in the
case of cathodic dip painting, the vehicle is entirely immersed in a tank
containing an acid/base mixture. It is at this stage in the process that a
voltage is applied and the metal is coated with anti-corrosion treatment,
explains Jan-Erik Butt.

The solution that the plant was looking for needed to
stand up to these harsh conditions. As a result, the project team opted for
single-use passive RFID labels. These can withstand extreme stress and are easy
to mount on the car body, then remove during final assembly. “The start of car
body production marks the point at which a main chassis beam is inscribed and
customized. It is also at this point that it receives its order number and we
affix the RFID label. This is the first time that variation comes into play,
and we use this for identification purposes. From then on, we always have RFID
features on the vehicle.” The RFID label is about the same size as a business
card and is made from Nomex material, which protects the antenna inside and the
chip against heat and other influences.

The changes that take place between one customized
vehicle and another being built are usually found in the assembly process, and
are dictated by the design that the customer has ordered. There is a very high
level of variation at this stage and it is therefore essential that vehicles
are correctly identified. Ultimately, each employee must know which vehicle
they have in front of them in order to customize it as appropriate. As well as
this, Audi has opted for a specific type of concept that makes it even more
important for the RFID solution to perform reliably. The RFID reading process
is linked to a belt stop, which means that the production line will come to a
standstill if RFID identification of a vehicle fails at any given point. In
this way, Audi can ensure that no vehicle leaves a station without having been
identified. The RFID label is eventually removed during final assembly,
sometimes on account of the sensitive production data it is associated with.

Standardized data overview for the entire process

For Jan-Erik Butt, another reason for relying on RFID
is the consistently high standard of data quality delivered by the readings at
every station. “If we acquire the same type of data from every area, we can
generate informative trend analyses, for example. This is because the reading
situations can be compared with one another. As a result, we are able to obtain
extensive information on the entire production process – something that just
wouldn’t be achievable if we were using a mixed bag of technology. And that
naturally gives us the opportunity to take an entirely different approach – to
put preventive measures in place rather than simply responding to situations
all the time. For example, we are working on methods of observing how reading
quality gradually deteriorates and intervening before problems occur.”

The perfect function for specific applications

As part of its RFID solution, the Audi site in
Neckarsulm is using the SICK AppSpace eco-system, which allows tailor-made
sensor apps to be programmed with ease. “We want to harness new ways of
processing data further, exactly in line with our needs. For example, we are
implementing SICK AppSpace at reading points in order to allow the antenna to
communicate directly with the MES system that we use to control production, and
to do so in the appropriate format for the recipient. Without the need for any
additional middleware, we are able to create a service-based architectural
framework, such as OPC UA, that is not reliant on any particular platform or
manufacturer. This means that we don’t have to change all the system settings
each time reprogramming takes place. Instead, we can use an app to remotely
determine how the antenna is to process and transfer data. We want the ability
to operate a whole range of different functions flexibly within a single
reading device. It therefore makes sense to use an antenna that is more
intelligent too.”

RFID as an overarching identification strategy

Summing up, Jan-Erik Butt has a positive view of how
things have progressed: “If we compare the situation before and after, we can
see that the successful switch to the new technology has led to an increase in
availability and even significant time savings in many cases. In contrast to
the original proprietary systems, commissioning RFID antennas is less

What started as part of a vehicle project, and was
designed for a specific product derived from another product, has now been up
and running throughout the plant for some time now: “The results we have gained
from the RFID identification process have won us over. Instead of RFID only
being used in a single hall or as part of a single vehicle project, the
Neckarsulm site is using it for identification purposes at every stage of production.”

Written by Martin Demharter, Key Account Manager Automotive Industry,
SICK Vertriebs-GmbH, Düsseldorf

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