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Load Conveyor
Unload Conveyor
M1
M2
Defined Area
Hard Guarding
Load
Unload
Retroreflective Targets
at Each Position to
Initiate a Mute
Milling and Drilling
Operations
Muting Sensors and
Retroreflective Targets
at Different Heights
and Positions
Figure 36. A typical application for turret table inspection or operation station muting, using retroreflective photoelectric sensors as muting devices
8.1.5 Power Press Applications
Muting is allowed on power presses only during the nonhazardous portion of the cycle (for example, the upstroke), per
OSHA1910.217, ANSI B11.1, B11.2, and B11.3. The mute permits the insertion or removal of material into the press that
would otherwise block the sensing field of the safety light screen, causing the press to stop. Muting should not be confused
with Inch or Jog modes, whose manual selection may bypass the safety light screen within the machine control.
For the proper application of muting on a power press, at a minimum, two (or four) independent position switches (such as
cam-operated limit switches, inductive prox sensors, or pressure switches) must be used to initiate the mute during the
nonhazardous portion of the machine cycle. These position switches would be mute devices M1/M2 (and M3/M4 if used).
Typically, these switches have normally open contacts, which are held (or actuated) closed during the mute cycle.
These switches must be mounted separately to prevent misadjustment, misalignment, or a single common mode failure,
which would result in an improper mute cycle or otherwise unsafe condition. They must be installed so that they can not be
easily defeated or bypassed, and their adjustment should be under supervisory control.
The two (or four) muting devices must be properly adjusted (or positioned) so that they close only after the hazard no longer
exists and then open when the cycle is complete (top of stroke) or when the hazard is again present. If improperly adjusted
or positioned, injury or death could result.
EZ-SCREEN Low-Profile System with Integral Muting
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