n recent years, China has grown to become the
world’s most important automotive market next to
the USA. This is benefiting Chinese manufacturers.
The production complex of a Chinese car manufactur-
er – and Turck customer – managed to achieve sales
of around 2.4 billion euros. The upstream and down-
stream industrial sectors, such as the supplier industry
or logistics also benefit from this economic strength.
The car manufacturer has belonged to the premier
league of the Chinese automotive industry for sev-
eral years. In order to increase its annual production to
300,000 cars, the manufacturer added a production line
to its production plant. The investment for the paint line
alone was almost 40 million euros. Today 150,000 car
bodies are painted here each year. As well as the con-
struction of the paint shop, the project involved a press
shop, the body construction section, as well as an assem-
bly line including engine production. With BL Com-
pact fieldbus stations and connectivity products, Turck
ensures that the signals of the field devices of the paint
line are sent to the controller reliably and cost effectively.
30 APPLICATIONS_FlELDBUS TECHNOLOGY
I
Painting in Extremes
A Chinese car manufacturer uses Turck’s BL compact stations, connectivity products
and proximity switches in its new paint shop
Harsh ambient conditions in
the paint line
The car body parts are first pressed, welded to form
the chassis and then painted. Oil and grease are first
removed in the paint line at high temperature from
the surface of the chassis using high pressure jets. The
subsequent cathodic immersion painting process and
a phosphating process protect the car body from oxi-
dation and corrosion, i.e. rust. After thorough pre-treat-
ment, the chassis is primed, painted and then dried.
This multi-stage painting process, the high level
of automation in the plant, and the different process
steps coordinated in the extremely harsh conditions
present the automation components used and the
integrator with a particular challenge. The restricted
space and the combination of factory automation and
industrial process requirements made the search for a
solution even more difficult.
The central task of the project was to automate
the transport system of the paint line. It is based on an
Robust: The fully
encapsulated BL
compact modules are
fitted directly on the
steel support of the
skid conveyor system
Webcode
more11355e
Author
Li Tao works in the marketing engineering department at Turck China in Tianjin
With their large operating distance,
the proximity switches guarantee
the reliable detection of the switch
positions
more
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The Y junction cables carry two signals via an M12
male connector to the input to the bus
Paint processes present particularly demanding requirements on automation
components. Turck’s IP67 BL compact fieldbus stations withstand all the harsh
environmental conditions in the plant of a Chinese car manufacturer and transfer
the switch signals of the skid conveyor system cost-effectively to the controller.
The matching connectivity products and inductive proximity switches from Turck
round off the robust solution.
Quick read
automated skid conveyor system. The autonomous and
safe control of the skids on the rails requires the use of
many position measuring points, sensor signals and
motor control signals. The fieldbus stations have to pro-
cess the corresponding number of inputs and outputs. A
central I/O station to collect and process all the inputs of
the plant would have been more expensive due to the
cabling involved. Troubleshooting in the event of a fault
can also be very time consuming, depending on the
type of central I/O station used.
Open standard
The customer’s specifications included the alignment
and control of the paint robot as well as the flexible
integration of the conveyor belt systems – and all this
while maintaining a constant level of production effi-
ciency in full operation. The responsible engineers
wanted an automation system that was based on an
open protocol and which could be implemented with
standard cabling.
It was decided to use DeviceNet. This fieldbus stan-
dard is an open protocol that provides the level flex-
ibility to optimally meet the requirements of the paint
shop. Due to the size of the plant, the installation of
compact I/O stations in the field was recommended.
This made it unnecessary for every single sensor cable
to be routed through the entire plant. Turck’s BL com-
pact stations are installed instead, which route all inputs
further via the bus cable to the next I/O station, and
then on to the master. Turck’s BL compact DeviceNet
modules with protection to IP67 were able to fully
meet the requirements of the application. The compact
modules are fitted on the steel support of the transport
system along the entire length of the paint line – also
directly next to the motor controller which coordinates
the entire transport of the skids.
The customer uses BL compact stations with 16
digital inputs (BL CDN-8M12S-8DI-P) and the smaller
version with eight digital inputs (BLCDN-4M12S-8DI-
PD). They form the backbone of the entire bus system
in the paint line. The 16 switch inputs are distributed to
only eight M12 female connectors in the highly com-
pact modules. One female connector routes two inputs
– the version with four connectors being sufficient for
eight inputs.
Extremely robust
The compact stations are fully encapsulated in epoxy
resin in order to achieve their tremendously robust
design and IP69K protection. The thermal performance
of the block modules is also impressive: They can with-
stand temperatures from -40 to +70 °C. Despite the
high temperatures, the paint line does not effect the
modules. The extensive diagnostic functions of the I/O
stations enable the customer to increase availability
and the required level of reliability. LEDs on the mod-
ule provide workers with reliable status indication of
the inputs locally in the field. The matching Y junction
cables as well as the bus cable likewise come from the
Turck portfolio.
Turck offers BL compact modules for analogsignals,
switch signals for connecting RFID read/write heads or
other signal types. Individual BL compact stations were
fitted with signal processors to meet the customer’s
special application requirements in order to save costs
on stations and cables. The system is perfectly matched
to the application, is easy to maintain, and also includes
proximity switches from the Turck portfolio as well as
the fieldbus stations and connectivity products.
The customer uses the Turck proximity switches
for position monitoring points in the skid rail system.
With their large operating distance, they guarantee the
reliable detection of the switch positions. The prox-
imity switches have the same EMC performance as
the fieldbus stations. A satisfied customer and a fault-
free production are the result of the intensive coop-
eration between the car manufacturer in China with
its long-standing partner Turck.