4 - safe guarding of machinery

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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7

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

4 - safe guarding of machinery

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