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A leading manufacturing company has been providing highly
engineered
coating and laminating machinery to industrial customers worldwide since
1882. The company has now made its machinery even safer to operate, as
a
result of having standardized on advanced safety switch technology.
The Company’s roll coating machines are used in a variety
of industries to
apply liquid materials of many types to virtually any flat surface product.
Examples include varnishes, glues, inks and paints that are metered onto
rollers and subsequently onto products ranging from residential and
commercial countertops and doors, to ceiling tiles and wall paneling,
to
leather and carpeting. Nearly 25,000 of this company’s coaters and
laminating machines are in use worldwide today.
In 2000, the company decided to update its roll coaters
with safety
equipment that was more defeat resistant and which also was compliant
with the latest industry safety standards, including the rigorous European
CE certification. As a result, it has specified a safety interlock switch
and
relay system designed by Sentrol Industrial*, of Tualatin, Oregon, for
use on
its machine guards. The switch and relay, Sentrol’s 341-BT
and INT-03
Series, are mounted on the wire-mesh guard above the nip point where
the
two large coating rolls come together. Should an operator (unintentionally
or
intentionally) move the guard out of position while the machine is running,
the safety switch and relay will activate, causing the machine to come
to an
immediate stop
The Sentrol 341-BT earned the CE certification, and subsequent
selection
by virtue of its non-contact design. This design positions the switch
and
magnetic actuator apart from each other (one on the guard and the other
on the machine) by a distance of between 0.5 inch and 1.0 inch. When this
distance is increased by the opening of the guard the switch is activated
and stops the machine, typically in less than 50 milliseconds. The INT-03
relay is an additional and important element in the system. It performs
a
continuous check of the 341-BT’s circuitry, and will trigger a shut
down and
also prohibit machine re-start if it detects a failure in any of the switch’s
componentry. A single INT-03 relay can monitor up to 50 switches.
Before selecting the Sentrol switch and relay, the company
installed and ran
the system on a machine in its testing lab for a period of one year. “We
did
our best to defeat it by any means normally expected, but could not,”
said
the company’s project engineer. “The only way we could defeat
it was by re
working the electrical power to it, which someone intending to over-ride
it
would be unlikely to do. Based on the success of the test, we committed
to
the switch and relay combination and have since installed it on several
hundred machines ordered by our customers.”
Also factoring into the selection decision was the durability
of the 341-BT.
Both the switch and activator are encased in a KynarÆ Polyvinylidene
Fluoride housing. This allows them to operate reliably in the harshest
of
environments, such as those where the company’s equipment is used.
The
switch is impervious to chemicals and liquids and can operate reliably
in
temperatures ranging from 14 degrees to 150 degrees Fahrenheit (10
degrees to 65 degrees C), and has a rated life cycle of 100,000 operations.
“It will more than stand up to the treatment that our machines are
exposed
to,” the project engineer added.
He said further that the 341-BT’s built in LED status
light was a factor as
well. The green light is illuminated as soon as an out of position condition
is
detected, enabling the operator to immediately know the reason for the
shut down situation.
“Sentrol was responsive to our request for specialized
support,” the
project engineer added. He explained it is not uncommon for our machine
to
sit for weeks in a customer’s factory before it’s installed,
during which time
capacitors inside the relay can bleed down causing the 341s fast-blow
fuse
to trip with the in-rush of high current on machine start-up. “We
explained
the problem to Sentrol and they were very quick to specify a time-delay
fuse that solved the problem. That’s an example of solid customer
support.”
Sentrol Industrial offers one of the industry’s most
complete lines of
safety interlock switches, relays, position sensors and related products.
These products, which have been specified for use in thousands of industrial
equipment applications, are acknowledged for their durability and
dependability. They are subjected to rigorous testing, and in many cases,
offer life cycles up to 1,000,000 operations. Sentrol’s products
also fully
comply with the most current and required standards, including IMQ, CE,
VDE, UL, CSA, IEC and EN.
*Sentrol and Sentrol Industrial are now GE Security Industrial
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