Monitoring 100,000 engines
per year
John Deere, Saran (France)
To increase quality, simplify operations and saving time for the
whole assembly line John Deere uses a RFID system Simatic RF300
at the plant Saran near Orléans. From the initial bare cylinder block,
a fully assembled engine is born, the reference of which is recognized with no possible errors at each manual or automated assembly
operation.
The John Deere plant at Saran offers an
output of 100,000 diesel engines per year
(450 per day). Three engines ranges are
available, using a total of 500 references.
This means that, in one day, the assembly
line may handle up to 70 different batches. This flexible 220-metre long line
comprises 92 workstations, each corresponding to a specific assembly stage. For
each manual workstation, a screen indicates the reference of the part to be
assembled to the operator. Until now, the
AMES (a proprietary IT system common to
all John Deere sites) line supervision and
production monitoring system sent the
corresponding planning sheet to each
workstation, according to the principle
of the engine reference stacking system,
in the order of entry into production only.
However, about ten times per week, this
logical principle was causing time lag
issues.
SIMATIC Ident
Correcting these productivity and quality
defects sometimes meant that final corrections had to be made to the engines
offline. To solve this recurring problem,
John Deere decided to integrate a RFID
solution with Simatic RF300 from Siemens
for the purpose of monitoring the engine
assemblies.
Monitoring 100,000 engines per year
Engine and procedure are inextricably
linked
Tags on automated trolleys
On the first part of the line, the 50 automated transfer trolleys moving on rollers
each incorporate three passive RFID HF
tags. The Simatic RF320T tags are arranged on 3 sides of the trolley, since it has
to move in front of the readers on various
sides. At the edge of the line, the RF340R
readers are arranged. On the second part
of the line, the engine blocks leave the
trolleys to be put onto trucks, which are
guided by a rail that is built into the floor.
Each of the 70 trucks has a single tag in
this instance, which is read by Simatic
RF350R readers.
92 RFID antennas in a network
Each trolley has 3 RFID tags as it is required to
transfer to 3 different positions.
In order to provide a link to the production management system, an additional
Profibus DP network has been added to
connect the 92 RFID antennas and 50
communication modules of the ASM 456
type. This network is connected to a
Simatic S7-400 PLC, which is equipped
with a high-performance CPU 416 that
controls conveying for the entire assembly line.
For data routing purposes, the operator
establishes the relationship between batch
number and RFID tag number at the start
of the line when a trolley receives an engine block. Thus, when a trolley arrives in
front of a workstation, the antenna reads
the tag on the fly: the number is returned
via an Ethernet link between the PLC and
the OPC server on the AMES production
management system. The planning sheet
relating to the workstation and the batch
being processed is distributed by return.
All this information appears on the screen
at the operator's workstation. Errors are no
longer possible in the operation performed
on the batch.
Successful integration
The issue related both to the accuracy of
the distances between tags and readers
and the configuration choices as regards
any interference with the radio communications caused by the metal masses. It was
therefore necessary to make mechanical
modifications in order to adapt the RFID
technology to the various production constraints. Moreover, an adjustment of the
automatic control program has made it
possible to optimize the cycle time of the
PLC dedicated to conveying, which
handles instrumentation and control for
the 92 assembly workstations and operator interfaces.
The second part of the assembly line requires the
engine blocks to be put onto trucks that are
drawn by means of a rail. The RFID read/write
device is arranged below the flagstone level.
Siemens AG
Industry Sector
Sensors and Communication
P.O. Box 4848
90026 NUREMBERG
GERMANY
www.siemens.com/ident
© Siemens AG 2010
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