IMAE 3MM05
Machine Guarding
The Basic Rudiments at least
Why are
machines not
guarded?
• No one would stick their arm, hand,
finger, head, etc. in there.
• No one is supposed to be back there, in
there, around it while it is running.
• The machine came that way; it never
had a guard.
• I’ve been doing it this way for twenty
years without any problems.
Why are
machines not
guarded?
(cont.)
• The guard is in the way
• The OSHA inspector didn’t say anything
about it.
• We’ll put it back on if OSHA comes.
Where
machine
hazards occur:
• Point of operation
• Mechanical power transmission
• In-running nip points
• Other moving parts
In-Running Nip Points
Rotating
cylinders
Belt and
pulley
Chain and
sprocket
Rack and
pinion
Methods of
Machine
Safeguarding
 Guards
 fixed
 interlocked
 adjustable
 self-adjusting
 Devices
 presence sensing
 pullback
 restraint
 safety controls (tripwire cable, two-hand contol, etc.)
 gates
Guards
• Fixed
• Interlocked
• Adjustable
• Self-adjusting
Fixed Guard
Provides a barrier - a permanent part of the
machine, preferable to all other types of guards.
Interlocked Guard
When this type of guard is opened or removed, the
tripping mechanism and/or power automatically
shuts off or disengages, and the machine cannot
cycle or be started until the guard is back in place.
Interlocked
guard on
revolving drum
Adjustable Guard
Provides a barrier which may be adjusted to
facilitate a variety of production operations.
Bandsaw blade
adjustable guard
Self-Adjusting Guard
Provides a barrier which moves according to
the size of the stock entering the danger area.
Circular table saw
self-adjusting guard
Devices
• Presence sensing
• Pullback
• Restraint
• Two Hand controls and
trips
Pullback Device
• Utilizes a series of cables attached to the operator’s hands,
wrists, and/or arms
• Primarily used on machines with stroking action
• Allows access to the point of operation when the slide/ram
is up
• Withdraws hands when the slide/ram begins to descend
Two-Hand Control
• Requires constant, concurrent
pressure to activate the
machine
• The operator’s hands are
required to be at a safe
location (on control buttons)
and at a safe distance from the
danger area while the machine
completes its closing cycle
1910.215(a)(4)
• Work rests shall be adjusted closely to
the wheel with a maximum opening of
one-eighth inch to prevent the work
from being jammed between the
wheel and the rest, which may cause
wheel breakage.
1910.215(b)(9)
• The distance between the wheel
periphery and the adjustable tongue or
the end of the peripheral member at
the top shall never exceed one-fourth
inch.
1910.212(b)
‹#›
 Machines designed for a fixed
location shall be securely
anchored to prevent walking or
moving.
OSHA Machine
Guarding
Standards
(Creates Issues)
‹#›
• 1910.212 General Requirements
•
.213 Woodworking
•
.215 Abrasive Wheels
•
.217 Mechanical Presses
•
ETC………..
And Other Machine or
Material Specific
One of the Challenges