Chapter 14 - Mechanical Hazards and Machine Guarding
safeguarding
machine safeguarding is to minimize the risk of accidents of machine-operator contact
main mechanical hazards associated with robots
- entrapment of a worker between a robot and a solid surface -impact with a moving robot arm -impact with objects ejected or dropped by the robot
common mechanical injuries
-cutting and tearing -shearing -crushing -breaking -spraining/straining -puncturing
characteristics of safeguards
-prevent contact -be secure and durable -protect against falling objects -create no new hazards -no interference -allow safe maintenance
energy control procedure must contain:
-statement on how the procedure will be used -steps used to shut down, isolate, and secure machines/equipment -steps explaining safe placement of lockout/tagout devices -instructions for next shift
safety trip devices
include trip wires, trip rods, and body bars -stop the machine when tripped
energized
machines, equipment, and tools are energized if they are connected to an energy source or when they still contain stored energy even after being disconnected
photo-electric devices
optical devices that shut down the machine whenever the light field is broken
fixed guards
permanent barrier between workers and the point of operation
lockout
placing a lockout device on a energy-isolating device to prevent the accidental energizing of a machine during maintenance or servicing
tagout
placing a tag on energy-isolating devices to want people so that they do not accidentally energize the machine
adjustable guards
provide a barrier against a variety of different hazards associated with different production operations
restraint devices
pull the operator back from the danger zone
pullback devices
pull the operator's hands out of the danger zone when the machine starts to cycle
two hand controls
require the operator to use both hands concurrently to activate the machine
interlocked guards
shut down the machine when the guard is not securely in place or disengaged
robot's work envelope
the three-dimensional area established by the robot's full range of motion - the best safeguard for a robot is a barrier around the work envelope
guarding point of operation
any point of operation that might expose a person to injury must be guarded
radio-frequency devices
capacitance devices that brake the machine if the capacitance field is interrupted
