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I really wish they would make light
curtains available in more colors, don't you?
Their appearance always clashes with the machinery. The
silver and black parts picker looks HORRIBLE next to those yellow light
curtains. Some people say black is neutral--but me, honey please! Don't even
get me started on these orange coveralls!
I say there is nothing wrong with being fabulous while also doing a
little hard work.
So is the life for that fashionably-perfect in the
manufacturing world. However, those light curtains do keep this tight tush
nice and safe.
A light curtain's main advantage is that it does not
impose a physical barrier on personnel. As such, an operator is able to access
guarded components without mechanical or observational limitations. Maintenance
processes are also eased by their use. Light curtains can be used
to monitor cargo in or out of a restricted access area, as well as
provide strictly one-way access.
A transmitter is established and an array of
parallel infrared beams provide a boundary across the restricted
access point. The transmitter can emit its rays in virtually any configuration
provided the infrared beams conclude at a receiver. Mirrors are frequently used
to relay beams around corners or obstacles which reduces the need for multiple
transmitters, but for every mirror the beam range is reduced by
25%. An alignment laser or LED indicator is frequently
integrated in the transmitter for accurate positioning. Manufacturers may elect
to incorporate light curtains in standalone machinery and these devices
will have increased sensitivity. Light curtains have variable and
convenient installation patterns.
The infrared light beams are sequenced and
modulated and the receiver is designed to recognize
a specific infrared beam, decreasing the chance for issues from
ambient infrared light. When a beam is obstructed by an opaque object, a
safety relay halts the machinery or process within milliseconds. Some light
curtains allow the process to resume once the obstruction is removed, while
others require an operator to manually restart the process. A PLC
(integral or external) is required for the light curtain to interface
with the machinery it encloses. A timed mute feature
allows operators to control the flow of materials through the perimeter
without stopping the machine. Some muting scenarios allow the passage of
humans, while if other muting sensors register a human or
irregularity then the process will cease.
And while it may not be available in say, polka dots or
glittery pink (my fave!), many light curtains offer much more important
features. Self-checking circuitry has the capability to run a self-check during
startup, operation, or continuously to ensure no loss of function. Latching
safety relays will not remove the stop signal until the controls are manually
reset outside the protected area. And muting is the temporary, automatically
controlled deactivation of a safeguarding device during the non-hazardous
portion of the machine cycle.
Anyhow, you can learn all about light curtains at the GlobalSpec Light Curtain Selection Guide. And though the search filter doesn't
have a category for color, it can be useful for some other solutions.
Excuse me, time for lunch with the boys from floor 3 .
Ciao!
(Images credits: Southern Industrial Equipment; Industry Direct)
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