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8/10/2019 4 - Safe Guarding of Machinery
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SAFE GUARDING
OF MACHINERY
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LE RNING OBJECTIVE
At the end of this session participantshould be able:
i. State 2 importance of machinery protection
ii. List down 2 selection of machinery
protectioniii. Describe 5 categories of machinery
protection
iv. Identify statutory requirements related to
machinery protection
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SCOPE
1. Machinery Protection2. Statutory Requirement
3. Methods of Machinery Protection
4. Categories and Types of Protection5. Conclusion
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STATUTORY REQUIREMENTS
Occupational Safety and Health Act 1994(1994) Employers Responsibilities (Section15 (2):
a) Provide and maintain plant and system of workthat are, as far as practicable, safe and withoutrisks to health
b) Make arrangements for ensuring, so far as
practicable, safety and absence of risks to healthin connection with the use or operation,handling, storage and transport of plant andsubstances
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STATUTORY REQUIREMENTS
Factories and Machinery Act 1967 (FMA
1967)
Factories and Machinery (Fencing ofMachinery Safety) 1970 :
Applicable to all hazardous
machinery
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MACHINERY PROTECTION
The method may be used to identify the
safety level:
Design
Position
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Introduction
Crushed hands and arms, severed fingers, blindness -
the list of possible machinery-related injuries is as long
as it is horrifying. Safeguards are essential for protecting
workers from needless and preventable injuries.
A good rule to remember is: Any machine part, function,
or process which may cause injury must be safeguarded.
Where the operation of a machine can injure theoperator or other workers, the hazard must be controlled
or eliminated.
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Causes of Machine Accidents
a. Reaching in to clear equipment
b. Not using Lockout/Tagoutc. Unauthorized persons doing
maintenance or using the
machinesd. Missing or loose machine guards
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Where Mechanical Hazards Occur
I. Point of operation
II. All parts of the machine which move, such
as:
a. flywheels, pulleys, belts, couplings,
chains, cranks, gears, etc.
b. feed mechanisms and auxiliary parts of
the machineIII. In-running nip points
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Point of Operation
That point where work is performed on thematerial, such as cutting, shaping, boring,or forming of stock must be guarded.
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Rotating Parts
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In-Running Nip Points
Belt and
pulley
Chain andsprocket
Rack and
pinion
Rotating
cylinders
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Requirements for Safeguards
I. Prevent contact - prevent workers body or clothing
from contacting hazardous moving parts
II. Secure - firmly secured to machine and not easilyremoved
III. Protect from falling objects - ensure that no objectscan fall into moving parts
IV. Create no new hazards - must not have shear points,jagged edges or unfinished surfaces
V. Create no interference - must not prevent worker
from performing the job quickly and comfortablyVI. Allow safe lubrication - if possible, be able to
lubricate the machine without removing thesafeguards
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Methods of Machine Safeguarding
Guardsfixed
interlocked
adjustable
self-adjustingDevices
presence sensing
pullback
restraintsafety controls (tripwire
cable, two-hand contol, etc.)
gates
Location/distanceFeeding and ejection methods
automatic and/or semi-
automatic feed and
ejection
robots
Miscellaneous aids
awareness barriers
protective shields
hand-feeding tools
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Fixed Guard
Provides a barrier - a permanent part of themachine, preferable to all other types of guards.
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Interlocked Guard
When this type of guard is opened or removed, thetripping mechanism and/or power automatically
shuts off or disengages, and the machine cannot
cycle or be started until the guard is back in place.
Interlockedguard on
revolving drum
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Adjustable Guard
Provides a barrier which may be adjusted tofacilitate a variety of production operations.
Bandsaw blade
adjustable guard
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Self-Adjusting Guard
Provides a barrier which moves according to
the size of the stock entering the danger area.
Circular table sawself-adjusting guard
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Pullback Device
Utilizes a series of cables
attached to the operators
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 theslide/ram begins to descend
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Pullback Device (cont
d)
Hands in die, feeding
Point of operation
exposed
Pullback device attached
and properly adjusted
Die closed
Hands withdrawn from
point of operation by
pullback device
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STOP DEVICE
Uses a cable connected to a fixed
machine part that is attached to the
workers hand or arm
Weakness: May be easily bypassedby the operator
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SAFETY CONTROL DEVICE
Manually activated and needs to be
manually reset to start machine
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TYPES OF CONTROL DEVICES
Safety Trip Control
Pressure Sensitive Body Bar
Safety Trip-Rod DeviceSafety Trip Wire Cable
Two-Hand Control
Two-Hand TripFencing
PRESSURE SENSITIVE BODY
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PRESSURE SENSITIVE BODY
BAR
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SAFETY TRIP-ROD DEVICE
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SAFETY TRIP WIRE CABLE
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TWO-HAND CONTROL
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PROTECTION USING ISOLATION
Can be implement in:
Position
Distance
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POSITION
The hazardous part is placed at the
location that is not easily accessibleor hard to reach so as to avoid
contact that may injure the human
body
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PRINCIPLE PROTECTION
USING ISOLATIONOperation feeding process
Control of operator position
O C O S G
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PROTECTION USING
OPERATION
Automatic feeding
Semi-automatic feedingAutomatic production
Semi-automatic
productionRobotics
PROTECTION USING
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PROTECTION USING
OPERATION
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Restraint Device
Uses cables or straps attachedto the operators hands and a
fixed point
Must be adjusted to let the
operators hands travel within
a predetermined safe area
Hand-feeding tools are often
necessary if the operationinvolves placing material into
the danger area
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Safety Tripwire Cables
Device located around
the perimeter of or
near the danger area
Operator must be ableto reach the cable to
stop the machine
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Two-Hand Control
Requires constant,concurrent pressure to
activate the machine
The operator
s hands arerequired to be at a safe
location (on control
buttons) and at a safe
distance from the dangerarea while the machine
completes its closing cycle
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Gate
Movable barrier device which protects the
operator at the point of operation before themachine cycle can be started
If the gate does not fully close, machine will not
function
Gate Open Gate Closed
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Safeguarding by
Location/Distance
Locate the machine or its
dangerous moving parts
so that they are not
accessible or do not
present a hazard to a
worker during normal
operationMaintain a safe distance
from the danger area
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Automatic Feed(shown on power press)
TransparentEnclosureGuard
Stock FeedRoll
DangerArea
Completed Work
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Robots
Machines that load andunload stock, assemble
parts, transfer objects, or
perform other tasks
Best used in high-
production processes
requiring repeated
routines where theyprevent other hazards to
employees
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Protective Shields
These do not give complete protection from machinehazards, but do provide some protection from flying
particles, splashing cutting oils, or coolants.
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Holding Tools
Used to place and
remove stock in the
danger area
Not to be used insteadof other machine
safeguards, but as a
supplement
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Some Examples o f Mach ine
Guard ing Requ irements . . . .
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Abrasive Wheel Machinery
Work rests on offhand grinding machines must be keptadjusted closely to the wheel with a maximum opening
of 3mm to prevent the work from being jammed
between the wheel and the rest, which may result in
wheel breakage.
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Abrasive Wheel Machinery
The distance between the wheel periphery and theadjustable tongue must never exceed 1/4-inch.
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Power-Transmission Apparatus
Power-transmission
apparatus (shafting,
flywheels, pulleys, belts,
chain drives, etc.) lessthan 6 feet from the floor
or working platform must
be guarded.
Unguarded belt
and pulley
M hi S f t R ibiliti
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Machine Safety Responsibilities
Management
> ensure all machinery is properly guarded Supervisors
> train employees on specific guard rules in their areas
> ensure machine guards remain in place and are
functional> immediately correct machine guard deficiencies
Employees
> do not remove guards unless machine is locked and
tagged> report machine guard problems to supervisors
immediately
> do not operate equipment unless guards are in place
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Training
Hazards associated with particular machines
How the safeguards provide protection and the
hazards for which they are intended
How and why to use the safeguards How and when safeguards can be removed and by
whom
What to do if a safeguard is damaged, missing, or
unable to provide adequate protection
Operators should receive training on the following:
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Summary
Safeguards are essential for protecting workersfrom needless and preventable machinery-
related injuries
The point of operation, as well as all parts of the
machine that move while the machine is
working, must be safeguarded
A good rule to remember is: Any machine part,
function, or process which may cause injury
must be safeguarded