Orders for 24 hours a day
The plant in Windsor, Ontario, is a joint venture between Nemaks parent, Alfa, one of Mexicos largest industrial
conglomerates, and the Ford Motor Company. The facility supplies its products to Ford engine plants in the U.S.
Nemak is a world-renowned innovator in the design and manufacture of aluminum cylinder head and block
castings. Its success is measured by the overwhelming acceptance of its
technology. The company is now the largest aluminum cylinder head producer in the western
hemisphere, and there is no let-up in demand for its products. Growth is fuelled by the value automakers
are placing on the critical weight advantage inherent in aluminum. Responding to its strong order book means
Nemak must maintain full production.To do this it employs the most advanced technologies and maintains
an ongoing interest in enhancing production.Thus, reducing the time it takes to reset after faults in a plant
running 24 hours a day held considerable attraction for management.
Reduce downtime
Nemak has developed the expertise to create blocks characterized by the highest quality, best mechanical
properties and exceptional machinability. Work in progress is ferried by an inverted monorail-type conveyor
to twenty robotic cells that carry out core assembly and are placed along the mould assembly line. As is the case
in most plants, a fault usually occurs at the farthest distance from an electrician. The electrician may have to
walk up to 350 feet to clear the fault. It was my view that this is too much time spent with part of the line down,
explains Libonati.
The Panel project
Now resets can be done at strategically placed Siemens push-button HMI panels. Each serves two cells, with
the resulting network connected in daisy-chain fashion. Messages are conveyed to programmable logic
controllers (PLCs) and other devices through a Profibus multi-point interface (MPI)
communications network. MPI is both a programming and peer-to-peer networking
connection. Typically, the interface establishes a sub-net in which central process units, HMI user
interfaces and programming devices can simultaneously exchange data. Profibus, used for
master/slave, peer-to-peer and dynamic communication strategies, is now an industry standard for in-plant
device communication.
One of the advantages of selecting Siemens is that the panels keys and lamps were configured prior to
installation. Pre-wiring and pre-testing contributes to reducing installation by up to 90%.This was a consideration for
Nemak, given that its panel project was a retrofit. But what is of greater value is the reliability of the Siemens
system: it is ready to go from the time it is turned on.
The standard panel configuration, with only a square installation cutout and an MPI bus cable, guarantees
immediate readiness for use after connection. Even though it is not a custom installation, various panel
options can be activated through parameter modification.
One of the intrinsic values of push-button panels, explains Libonati, is the use of multi-colour light-emitting
diode (LED) signalling lamps. These give an instant optical view of the line, which, he says, simplifies
operations.The colour codes for the LEDs include red, green and orange, with flashing capabilities.
Siemens push-button panels, while embodying everything found in conventionally designed operator panels,
also offer some extras. These include turnkey MPI operation, pre-assigned short-stroke keys, long-life two-colour
surface diagnostics functions and extra digital inputs and outputs to facilitate later expansion. Designed for simple
machine operation, Siemens push-button panels can be used wherever keys and lamps are required. For the
greatest ease of use, the compact Siemens panels feature easy-handling, menu-driven configuration. Given this,
they can be reconfigured in the shortest time possible.
Ultimately, the success of the panel project is measured in reduced downtime. Response time now, using the
panels, is half of what it used to be, reports Libonati.
"Eye on Automotive Productivity" 2002
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