MODULE 4 - CLASS NOTES - MCN401- INDUSTRIAL SAFETY ENGINEERING
MODULE
4 : (Safety hazards in machines)
Machinery
Safeguard-Point-of-Operation, Principle of machine guarding -types of guards
and devices. Safety in turning, and grinding. Welding and Cutting-Safety
Precautions of Gas welding and Arc Welding. Material
Handling-Classification-safety consideration- manual and mechanical handling.
Handling assessments and techniques- lifting, carrying, pulling, pushing, palletizing
and stocking. Material Handling equipment-operation & maintenance.
Maintenance of common elements-wire rope, chains slings, hooks, clamps. Hearing
Conservation Program in Production industries.
Machinery Safeguard
Moving
machine parts have the potential to cause severe workplace injuries, such as
crushed fingers or hands, amputations, burns, or blindness. Safeguards are
essential for protecting workers from these preventable injuries. Any machine
part, function, or process that may cause injury must be safeguarded.
·
to prevent contact with
body parts
·
to control hazards like
chips or sparks from exiting the machine.
·
to protect humans from
injury while working nearby or while operating equipment.
· It is often the first
line of defence to protect operators from injury while working on or around
machinery during normal operations
Point-of-Operation / Principle
of machine guarding
A
machine's point of operation is the area where its work is performed. These
points can include moving parts that have the potential to cause severe injuries. Machine operators often need to come
into close proximity to points of operation in the course of their work. In
those cases, machine guards can be installed to prevent hands or other body
parts from accidentally getting caught in those moving parts. One or more methods of machine guarding
to be provided in the machine area from hazards created by points of operation,
ingoing pinch points, rotating parts, and flying chips.
The
following are some of the machines which usually require point of operation
guarding:
·
Milling machines.
·
Power saws.
·
Portable power tools.
Selecting
an Adequate Machine Guard
·
Make sure that hands
and fingers can't reach past the guard
·
Use a guard that will
not introduce additional hazards
·
Select a guard that
does not compromise the operator's visibility
·
Guards should be made
of strong, durable material
·
Install guards that
cannot be adjusted or removed easily (i.e. without the use of tools)
·
Allow for lubrication
with the guard still in place - If possible, one should be able to lubricate
the machine without removing safeguards
·
Not interfere with the
machine operation - Proper
safeguarding can actually enhance efficiency since it can relieve the worker’s
apprehensions about injury.
Types of guards and devices
There
are several different types of machine guards. Guards are materials that keep
workers from having direct contact with moving parts and other dangerous areas
of a machine. Some guards also protect workers from shavings, flying shards or
metal sparks created by working machines. Any machine part that could cause
injury to be guarded. Guard design and material will vary from machine to
machine and from tool to tool. The most common types of machine guards are:
·
Fixed guards
·
Interlocking guards
·
Adjustable guards
·
Self-adjusting guards
1. Fixed
Guards
Fixed
guards are permanently attached to the machine or tool, don’t have any moving
parts, and can’t be moved while the machine is in use. They’re most often used
to enclose the point of operation, or other hazards that the operator doesn’t
need to interact with, like fan blades or flywheels. Because fixed guards are
permanent features of the machine, they must be disassembled and removed to
perform any kind of adjustment or maintenance.
2. Adjustable
Guards
Adjustable
guards, like fixed guards, are permanent, but they can be adjusted to allow the
machine to handle different sizes of material. They must be manually adjusted
and locked into place. If improperly adjusted or locked, adjustable guards can
fail to prevent contact with moving parts, causing serious or even fatal
injury.
3. Self-Adjusting
Guards
Self-adjusting
guards serve the same purpose as adjustable guards, but automatically adapt to
the size of the material. When the machine is at rest, these guards sit all the
way down. When the machine is in use, the operator feeds material into the
machine, which opens the guard just enough to let the material in. These guards
are commonly found on table saws and woodworking tools.
4. Interlocking
Guards
Interlocking
guards, also known as barrier guards, automatically shut off or disengage the
power source when the guard is open or removed. These are particularly useful
in situations where operators need to be able to open the guard or access the
guarded parts of the machine, such as when clearing jams. These guards allow
safe access to interior parts of the machine without requiring a total
disassembly. However, they can be easy to open on accident and require careful
adjustment and maintenance.
Other
devices are
5. Sensors
that instantly shut off the machine's power when an invisible barrier is broken
6. Safety
light curtains that use an emitter to send beams of light to the receiving,
creating a sensing screen that halts operation when it is breached
7. Trips,
such as floor mats or steel cables, that shut off power to the machine if the
worker touches them or enters a specified area
8. Restraints,
such as wrist straps or safety ropes, that keep a worker from hazardous areas
Safety in turning
To
avoid injuries, follow the safety precautions listed below.·
Always wear safety
goggles or safety glasses that include side protectors. Use a full faceshield
for bowl, vessel, or any turning involving chucks and faceplates.
·
Wear hearing protection
during extended periods of turning.
·
Turn the lathe off
before adjusting the tool rest or tool rest base
·
Remove chuck keys,
adjusting wrenches, and knockout bars. Form a habit of checking for these
before turning on the lathe.
·
Tie back long hair; do
not wear gloves; and avoid loose clothing, jewelry, or any dangling objects
that may catch on rotating parts or accessories.
·
When turning between
centers, be certain the workpiece is firmly mounted between the headstock
driving center and tailstock center.
·
Ensure the belt guard
or cover is in place.
·
Check that all locking
devices on the tailstock and tool rest assembly (rest and base) are tight
before operating the lathe.
·
Ensure the blank is
securely fastened.
·
Rotate your workpiece
by hand to make sure it clears the toolrest and bed before turning the lathe
on. Be certain that the workpiece turns freely and is firmly mounted.
·
Be aware of what
turners call the "red zone”. This is the area directly behind and in front
of the workpiece, the areas most likely for a piece to travel as it comes off
the lathe. A good safety habit is to step out of this zone when turning on the
lathe, keeping your hand on the switch in case you need to turn the machine
off. When observing someone else turn, stay out of this zone.
·
Always check the speed
of the lathe before turning it on. Use slower speeds for larger diameters or
rough pieces and higher speeds for smaller diameters and pieces that are
balanced. Always start a piece at a slower speed until the workpiece is
balanced. If the lathe is shaking or vibrating, lower the speed. If the
workpiece vibrates, always stop the machine to verify why. As a starting point,
consult your operator’s manual for recommended speeds for a particular lathe.
Ensure the lathe speed is compatible with the size of the blank.
·
Exercise extra caution
when using stock with cracks, splits, checks, bark pockets, knots, irregular
shapes, or protuberances. Beginners should avoid these types of stock until
they have greater knowledge of working.
·
Hold turning tools
securely on the toolrest, holding the tool in a controlled but comfortable
manner. Always contact the tool rest with the tool before contacting
·
Know your capabilities
and limitations. An experienced turner is capable of lathe speeds, techniques,
and procedures not recommended for beginning turners.
·
Always remove the tool
rest before sanding, finishing, or polishing operations.
·
Don’t overreach, keep
proper footing, and keep your balance at all times.
·
Keep lathe in good
repair. Check for damaged parts, alignment, binding of moving parts, and other
conditions that may affect its operation.
·
Keep tools sharp and
clean for better and safer performance. Don’t force a dull tool. Don’t use a
tool for a purpose that it was not designed for or intended for.
·
Consider your work
environment. Don’t use a lathe in damp or wet locations. Do not use in presence
of inflammable liquids or gases, and always keep a fully-charged fire
extinguisher close at hand. Keep your work area well lit.
·
Stay alert. Watch what
you are doing. Pay close attention to unusual sounds or vibrations. Stop the
lathe to investigate the cause. Don’t operate machines when you are tired or
under the influence of drugs or alcohol.
·
Guard against electric
shock. Inspect electric cords for damage. Avoid the use of extension cords.
·
Never leave the lathe
running unattended. Turn power off. Don’t leave lathe until it comes to a
complete stop.
·
Learn and follow the
safety guidelines for this equipment.
Safety
in grinding
Grinding
is the process of removing metal by the application of abrasives which are
bonded to form a rotating wheel. When the moving abrasive particles contact the
workpiece, they act as tiny cutting tools, each particle cutting a tiny chip
from the workpiece. Grinding machines
are used daily in a machine shop.
To
avoid injuries, follow the safety precautions listed below.
·
Do not use wheels that
are cracked or those that excessively vibrate.
·
Never operate grinding
wheels at speeds in excess of the recommended speed.
·
Never adjust the
workpiece or work mounting devices when the machine is operating
·
Do not exceed
recommended depth of cut for the grinding wheel or machine.
·
Remove workpiece from
grinding wheel before turning machine off.
·
Use proper wheel guards
on all grinding machines.
· On bench grinders, adjust tool rest 1/16 to 1/8 inch from the wheel.
·
Guards must be provided
and adjusted properly as per the manufacturers manual to protect you. Replace
damaged guards because if an abrasive wheel breaks while rotating, it can cause
a serious injury.
·
Follow manufacturer's
manual for the safe use of grinder.
·
Clean and service
grinders according to manufacturers' recommendations. Record all maintenance
for grinders.
·
Ensure that a machine
will not operate when unattended by checking the dead-man (constant pressure)
switch.
·
Ensure the floor around
the work area is clean.
·
Do not operate grinder
on wet floors.
·
Use both hands when
holding the grinder.
·
Keep the power cord
away from the grinding wheel and the material being ground.
·
When required, have a
hot work permit before use.
·
Make sure the work area
is clear of flammable materials and that combustible dust is not allowed to
accumulate.
Safety Precautions of Gas welding
Gas
welding process uses gases like acetylene and oxygen to produce flames.
Acetylene is flammable and hazardous. It has the ability to ignite and
condense. Whilst, oxygen helps other substances to burn faster. It does not
catch fire but can explode if exposed to fire. Hence To avoid injuries, follow
the safety precautions listed below.
Personal
protective equipment
1. Eye
goggles or safety glasses should use to protect the eye from infrared
radiation.
2. Protecting
clothing such as flameproof apron, gloves, cap or helmet, should be wear before
welding.
3. The
apron should be well fitted
4. Protective
clothing should be free from oil or grease. All these clothing should be in
good condition
Storage
and handling
1. Cylinders
should not be exposed to heat and should be securely chained to prevent from
falling.
2. they
should be kept away from flammable and combustible materials
3. they
should be store in a well-ventilated area
4. Acetylene
and oxygen cylinders should be store separately.
5. While
shifting, there should not be a drag, but rolling on a slow movement on bottom
edges.
6. Valves
on cylinders should be close before moving.
7. Regulators
and protective caps should be kept in place.
8. Keep
hands off grease or oil when opening or closing valves and regulators
Environmental
safety
1. Industries
or shops where gas welding is used should have proper ventilation, lighting,
walkways, store, escape route, safety poster, etc.
2. The
floor should be kept clean, free from water grease, and oil.
3. Fire
extinguishers should be easily accessible and welded jobs should be properly
stored.
4. The
ceiling height should be at least 16feet from the ground.
5. all equipment should be inspected before welding.
Work
and equipment safety.
1. Flame
arrestors must be fitted in acetylene and oxygen cylinder lines. One of them
should be fitted beside the low-pressure regulator and the other near the
touch.
2. Higher
pressure should release on oxygen than acetylene to avoid acetylene flame from
going back.
3. However,
acetylene should not be used when welding at a pressure exceeding 1bar of
atmosphere gauge to avoid explosion.
General
safety tips
1. Whenever
a backfire occurs, the oxygen valve should be close first and acetylene should
follow immediately.
2. Whenever
a flashback occurs, all hoses should be replaced with new ones.
3. Fittings
should be used to securely tighten all hose connections.
Safety Precautions of Arc Welding
Personal protective safety
This
safety is for the operators to protect their body from heat, flames and sparks
produce during the operation. The shielded metal arc welding type seems to
produce brighter lights, causing arc eye and skin irritation. That is why all
operators are expected to cover all parts of their skin before welding.
An
arc welding operator is expected to completely wear protective clothing such as
a long sleeve jacket (apron), heavy leather gloves, helmet with dark faceplate,
and booth.
Environmental
safety
1. Arc
welding should be carried out in a well-ventilated area, due to the dangerous
gases produced during welding. It causes the surrounding air to break down.
Proper ventilation is necessary to protect the welders from these hazardous
gases. There should be enough natural air entering into the workplace in order
to push out these gases.
2. The
environment should be wise and big enough with spaces with located walkways,
escape routes, stores, etc.
3. The
ground should be free from dirt, oil, grease, and water.
4. All
tools and equipment should be kept in the right place and jobs should be kept
away from walkways.
Operation
and equipment safety
1. Arc
welding operation should be performed in a covered place avoiding the
ultraviolet light to be exposed
2. The
welding power source should be kept away from sun, water, grease, and oil.
3. The
welding machine should not be a bridge, using the wrong power source for the
right machine.
4. All switches should be in order and be performing fine.
MATERIAL HANDLING
Material
handling is the preparation, placing and positioning of materials to facilitate
their movement or storage. "Materials handling is an art and science
involving the movements, packaging and storing of substances in any from".
In
most industries, the handling of materials, articles and equipment is one of
the main source of injuries. We are required to frequently lift, handle
material, and push or pull things in our daily life. Unfortunately, injuries
can happen if we do not use the proper technique equipment and get help as
needed.
Handling
and storing materials involves diverse operations such as hoisting tons of
steel with a crane, driving a truck loaded with aggregate or a concrete blocks,
manually carrying bags and materials, and stacking drums, barrels, lumber, or
loose bricks. The efficient handling and storing of materials is vital to
industry, These operations provide a continuous flow of raw materials, parts of
assemblies through the workplace, and ensure that materials are available when
needed. Yet, the improper handling and storing of materials can cause costly
injuries.
Major
contributing factors to the worker's injuries are: back injuries, body movement
(bending, twisting, and turning). In addition, workers can be injured by
falling objects, improperly stacked materials, or by various types of
equipment. When manually moving materials, however, workers should be aware of
potential injuries including the following:
(a)
Strains and sprains from improperly lifting loads, or from carrying loads that
are either too large or too heavy,
(b)
Fractures and bruises caused by being struck by materials, or by being caught
in pinch points, and
(c) Cuts and bruises caused by falling materials that have been improperly stored.
Safety considerations in Material
Handling
To
safeguard the worker from injuries due to materials handling, it is advisable
to use handling equipment carefully for safe, efficient and speedy handling of
materials. A safe and efficient material handling system improves the working
conditions, by way of following:
(a)
Safety aspects: Safety of men, materials and associated equipment not only
prevents loss of money but also enhances the moral or workers and improves
productivity.
(b)
Easy working: By using proper handling equipment heavy jobs can be handled with
ease, faster speed and at a constant rate throughout the period of production.
This enables high morale and lower worker turnover and high productivity.
(c)
Fool proof operation: Due to absence of manual handling, there are zero chances
of confusion resulting in higher productivity.
Safety
in Materials Handling
1. If
the material is very heavy and delicate in nature, ensure availability of
proper handling equipment.
2. Do
not leave the load in hanging condition.
3. Care
should be taken to see that no person comes under the load while hanging.
4. In
case of forklift, no counter weight shall be used by driver cabin to balance
load.
5. While
handling load with crane, working personnel should wear helmet and shoes.
6. Ensure
effectiveness of brake systems before using crane.
7. The
workmen should avoid.
(a) Lifting
too quickly or with a jerk.
(b) Lift
while in awkward position or with a poor footing.
(c) Handling
loads which are too heavy or too unwieldy to be handled by one man.
8. Aisles
and passages should be kept clear to provide for the free and safe movement.
9. The
materials should not be stacked to such a height so as to render the pile
unstable and
cause
hazards.
Classification
Equipment
used for material handling can be divided in following three categories:
1. Manual Handling
(with or without using Non-Powered Equipment)
Commonly
used Non-powered (manual) Equipment.
Hand
truck. Hand cart. Dolly. Trolleys. Baskets etc
Manual
handling means a range of activities including lifting, lowering, pushing,
pulling, carrying, moving, holding an object. It has been estimated that about
one-third of all work injuries occur during manual handling and most of them
cause 'back injury'. Following are the reasons of such injuries:
·
Work involving sudden,
jerky or hard to control movements or which causes discomfort and pain.
·
Work involving much
bending or twisting.
·
Work where a long time
is spent holding the same posture or position.
·
Work that is fast or
repetitive.
·
Heavy weight to be
lifted and carried manually.
·
Work where force is
needed to carry out a task.
·
The loads to be handled
below your mid-thigh or above your shoulder.
Some
of the solutions to deal with such injuries are
a)
Redesign the task or work area to make it safer, by
o Modifying
the object (shape, size or weight),
o Modifying
the work area or work station layout,
o Eliminating
unnecessary handling,
o Ensuring
that all heavy weights are at waist level where they can be handled
comfortably.
o Reducing
the amount of bending, lifting, twisting, reaching and holding required to carry
out a task,
o Modifying
the task by using tools such as levers, hooks, hoists, trolleys
o Providing
the training and information about safe working practices.
(b)
In order to neutralise the effect of wrong postures for long periods during
working, it is advisable to perform stretching exercises. Right type of
exercise can be selected and practiced under the guidance of experts.
Manual
handling equipment are manually operated and are used in the following
circumstances:
o
Where handling volume
is limited.
o
Where building or other
limitations do not allow the use of mechanised equipment.
o
Where capital for
investment is limited.
o
Where repair and
maintenance facilities are not existing.
o
Where utility,
flexibility, mobility and portability characteristics favour non-powered
equipment.
o
Where loads are light.
o
For standby use i.e.,
when mechanised equipment comes under breakdown.
2.
Mechanised Equipment
Commonly
used Mechanized Equipment are:
Gravity
conveyor, chute. Power conveyors (belt
or roller). Power truck (using pallet,
skid, platform etc.) Tractor-trailer. Train.
Overhead travelling crane.
Stacker crane. Monorail hoist.
These
equipments are used under following circumstances:
o
Loads are over a
particular weight say 22 kg.
o
Travel time is more
o
Unused space above
floor is available.
Points
in favour of mechanised material handling:
o
It can handle tough
works which cannot be performed by manual labour.
o
It is cheaper when
quantum of work is more a
o
material is required to
be transported for long distances.
o
It delivers safe and
better quality.
o
Time-bound targets are
easily achievable.
o
Lesser number of
persons are required.
Mechanized
equipment is recommended in following circumstances:
o
High volume.
o
Continuous movement of
material.
o
Much handling is
required.
o
Increased capacity.
o
Hazardous materials to
be handled.
o
Unit load concept is
applicable.
o
Manual handling not
practicable/possible.
3.
Automatic Equipment
Automation
in material handling ensures optimum mechanization with self-regulating control
of functions. Commonly used automated equipment are:
Tilting
cars/trucks Gravity, power conveyors. Automated trains. Automated overhead cranes. Automated hoists.
Automated
equipment’s are recommended in following circumstances:
o
High volume of material
to be handled.
o
Much handling.
o
Uniform
product/material.
o
Fixed material flow
pattern
o
Movement between two
points is fixed.
o Process control is maintained.
MATERIAL HANDLING TECHNIQUES
STAGING (STACKING) MATERIALS
Whenever
possible make sure that heavier materials are staged between thigh and chest
heights. This will make lifting easier and safer. Plan each lift and movement,
know your route and make sure that the path is clear. Place some empty pallets
under the material to raise the entire load to a convenient height for lifting.
Safe
techniques:
·
Keep your head up.
·
Keep the load close to
the body.
·
Use a staggered stance.
·
Do not twist yourself
along with the load.
·
Ensure that materials
are not stacked so high that they are in danger of toppling over or collapsing.
·
Store heavy items as
low as possible to the floor.
·
Ensure that loads are
properly secured against movement on pallets and pallets are in good condition
and are of appropriate size and type for the load.
·
Where possible, try to
stack articles of the same size and weight.
·
When stacking bags or
bundles of material, alternate rows, e.g., place one row running lengthwise,
the next running width wise, the third lengthwise and so on.
·
Ensure that, there is
adequate space to all workers, forklifts and other lifting devices to navigate
the workplace safely and efficiently.
·
Block or chock the
bottom tiers of round items, so that they do not shift or roll.
·
Ensure that materials
are not stacked so high that they block sprinklers; could come into contact
with ignition sources or are near the energized electricity wires.
LIFTING AND CARRYING MATERIALS
Lifting
appliances means a crane, hoist machinery, winch, pulley blocks, hooks 'or
other equipment used for lifting. Although most works are done mechanically in
the process of manufacturing, still many material handling works involving load
lifting are done manually. It has been experienced that a man can easily lift
about 22 kg and woman about 16 kg. But while doing work continuously in bent
position, even with a smaller load, there will be immense strains on spine and
back muscles that may result in injury especially for aged workers. Therefore,
efforts must be made to the material at a certain height so as to minimize the
strain and fatigue. Most lifting accidents are due to improper lifting methods
rather than to lifting too heavy loads.
No
machine shall be selected to do any lifting on a specific job until its size
and characteristics are considered against:
·
The weights, dimension
and lift radii of the heaviest and largest loads;
·
The maximum lift
height. the maximum lift radius and the weight of the loads that must be
handled at each:
·
the number and
frequency of lifts to be made;
·
How long the crane will
be required on site;
·
The type of lifting to
be done (for example, is precision placement of loads important?)
PULLING V /S PUSHING OF MATERIALS
·
It is easier and safer
to push rather than to pull a load.
·
Plan to push rather
than pull a load wherever possible.
·
Use these techniques
considering the minimization of the chance of injury.
·
Use the best material
handling equipment for the job.
·
Face the load squarely.
·
Grasp the handle or
load firmly.
·
Keep your elbows close
to the body.
· Do not twist your shoulders or arms when making a turn.
PALLETIZING
Palletization
is the assemblage and securing of individual items of work pieces on a
platform. Effective palletization can improve cycle times, reduce time and
labour costs of set-up. It is a method of storing and transporting goods
stacked on a pallet, and shipped as a unit load. It permits standardized ways
of handling loads with common mechanical equipment such as forklift trucks.
Loading
and unloading pallets of goods or produce are repetitive tasks that can easily
lead to injury, if the risks are not removed. Pallets are usually placed on the
ground and are loaded to the capacity of the truck or forklift that is used to
move them. This can lead to serious strains, and sprains from bending over,
awkward positions, using force in a stretched position, and lifting and manoeuvring
above shoulder height.
Manually loading pallets can lead to sprains and strains of muscles, ligaments, inter-vertebral discs and other structures in the back, arms, and shoulders. Workers work in awkward postures below knee height and above shoulder height which exposes them to a high risk of having a sprain/strain injury. The risk of injury is increased due to its repetitive nature and long period of time. Pallets are often stacked too high causing workers to handle loads in stretched and awkward positions.
MATERIAL HANDLING EQUIPMENT-OPERATION
& MAINTENANCE.
Maintenance
of a machine means efforts directed towards the upkeep and the repair of that
machine. maintenance is
responsible for the smooth and efficient working an equipment and helps in
improving its productivity. It also helps in keeping the machine in a state of
maximum efficiency with economy.
Objectives/Purposes of Maintenance
·
To maximise
availability of equipment for productive purposes.
·
To extend the life span
by minimising their wear and tear.
·
To ensure operational
readiness of equipment at all times.
·
To reduce breakdown.
·
To maintain plants and
equipment at its maximum operating efficiency, reducing downtimes
·
To safeguard
investments by minimizing rate of deterioration.
·
To help management in
taking decisions on replacement or new investments and actively participating
in specification preparation, equipment selection, its erection and commissioning.
·
Help in standardization
of spares and consumption.
·
To help in
implementation of suitable procedures for procurement, storage and consumption
of spares, tools and consumable etc.
·
To provide information
to the management on the cost and effectiveness of maintenance.
·
To ensure safety
through regular inspection and maintenance of plant, equipment and other
facilities
Functions of maintenance
1. Repair.
Repair includes fault location (trouble shooting), disassembly and assembly and
restore serviceability to an item by correcting specific damage, fault,
malfunction or failure of a part, subassembly.
2. Replace.
Replace means to remove an unserviceable item and install a serviceable
counterpart in its place.
3. Overhaul.
Overhaul is normally the highest degree of maintenance performed in the
industry. Overhauling is an effort to restore an item to a completely
operational condition.
4. Rebuild.
Rebuild means reconditioning or renovation for the restoration of unserviceable
item to a like new condition in accordance with original manufacturing
standards.
5. Inspection
or Check-ups. Inspection is an essential function of the maintenance programme.
crew carry out both the external and internal inspection. External inspection.
means to watch and detect defects from abnormal sound, vibration, heat, smoke
etc. when machine is in operation, while internal inspection means inspection
of internal parts, such as gears, bushes, bearing, tolerances in the parts,
etc., during the period when the machine is under pre planned shutdowns.
6. Servicing.
Mechanical components like gears, bearing, bushes and other friction surfaces
etc. give good performance for long periods, when they are systematically
lubricated. Systematic lubrication means the application of right type of
lubricant at the right time, at the right place and in right quantity. For
servicing, a schedule should be prepared and followed strictly. Servicing
includes cleaning, lubrication and check-ups.
7. Testing.
To verify serviceability by measuring the mechanical or electrical characteristics
of an item and compare them with prescribed standards.
8. Adjusting. Correct position or setting of the operating characteristics to specified parameters, adjustments are made to maintain the prescribed limits. Adjustments are made by way of making correct alignments, calibration and measurements.
9. Planning
and Scheduling. Every maintenance work should be pre-planned in detail on the
basic of the analysis done on the past records. A scheduled programme thus
prepared should be followed strictly. Thus programme should be in detail
specifying the points, required daily, weekly, monthly, half yearly or yearly
attention. Recommendations of the equipment manufacturer should also be kept in
view.
10. Record
and Analysis. Good record keeping is essential for good maintenance as it helps
in forecasting maintenance. For this purpose, following records are generally
maintained: (i) Operation manual, (ii) Maintenance Instruction Manual, (iii)
History Cards and History Registers, (iv) Spares Procurement Register, (v)
Inspection Register, (vi) Log books, (vii) Defects Register etc. With the help
of these records, possible cause for major repetitive failures can be examined
and rectified so as not to repeat so early.
MAINTENANCE OF WIRE ROPE
Wire
ropes are well known for their strength; they are used in many different
capacities. wire ropes don’t last forever. They are built to endure, but how
long they can be in use depends on how well they are cared for. Care and
maintenance for wire rope are essential.
1. Protection
Will Extend the Life of Wire Ropes
Protection
and inspection will extend the life of your wire ropes. To protect wire ropes
you must store them in a cool, well-ventilated, dry place, preferably up off
the floor to protect from possible water damage. Take care not to drop ropes,
especially when in a reel or coil. This will damage the ropes.
2. Daily
Inspection is Required
Make
sure a professional examines the ropes before each and every use. These experts
know what to look for and can identify deterioration, corrosion, and wear that
an untrained eye may not see. Ropes must be removed every few months for a
thorough inspection to make sure they are strong and undamaged to maintain
safety.
3. Lubrication
is Key
An
important final ingredient in the manufacturing of wire ropes is lubrication.
This keeps the ropes strong and pliable. Original lubrication is eventually
lost to heat and evaporation due to stretching and bending of the cable.
Regular use of the rope requires relubrication after the original evaporates,
The reason a rope must be relubricated is to protect the wire and its core and
to minimize corrosion, thus extending the life of the cable.
4. Cleaning
the Rope
Also,
if the cable gets dirty and particles get inside, it must be cleaned with a
petroleum solvent and wire brush before relubrication. A steam cleaner or
compressed air would also do the job, but either way, it must be dried and
lubricated immediately thereafter. Moisture must be avoided at all costs for
the preservation of your wire rope. However, to prevent safety hazards,
excessive lubrication must be avoided.
5. Corrosion
and Oxidation
To lengthen the life of wire ropes, it’s important to avoid corrosion and oxidation of the ropes caused by salt air, salt brines, acid, sulfur, gasses, humidity, or fumes. When shutting down a machine for an extended amount of time, the wire ropes must be removed, cleaned, re-lubricated, and stored properly. To reduce corrosion of the cable, adequate lubricant must be properly applied in the field.
6. Removing
from Reels or Coils
When
removing the rope from reels or coils, the coils or reels must rotate. Unloading
of the rope in a different manner will cause a kink in the rope, severely
limiting its strength. Unwinding a rope from a stationary reel will result in
kinks.
7. Lowering
and Recovery
Due
diligence must be exercised during lowering and recovery operations to ensure
even spooling on winch drums. Smooth re-spooling is necessary to keep the wire
rope in tiptop shape.
8. When
to Remove a Wire Rope
Wire
ropes are used for their strength and durability, but nothing lasts forever.
You can extend the life of your wire ropes by following the guideline listed above,
but when it shows signs of wear such as a reduction in diameter, broken wire,
kinks, birdcaging, nodes, flattened areas, misplacement of outer wires, heat
damage, corrosion, loose wires or loop formations, it must be removed from
service.
MAINTENANCE OF CHAINS SLINGS
Lifting
slings are an essential facet of the lifting equipment. Slings come in many different
types including chain slings, wire rope-slings, and round slings, etc. Each
sling will have its own individual purpose
A
thorough examination must be carried out by competent person at least once in 12
month or according to statutory regulations,
·
Position the wire rope
sling in a way that every part is viewable and accessible to the inspector.
·
The inspector will
remove dirt and apply grease using a wire brush to reveal fittings and wires.
·
The inspector will
closely inspect the sling to test the parts with a high chance of wear and
tear.
·
The inspector will also
focus on the end attachments, fittings, and the parts adjacent to those
fittings.
·
The inspector will look
for the damaged and worn-out parts of the wire rope sling. The inspector will
also label the parts that were already inspected.
Be
sure to keep a record of your sling inspections. A record will help you keep
track of your last inspection date and sling conditions.
When
to Replace Your Old Slings
You
may find some signs of damages after the inspection. However, that doesn’t mean
it’ll be easy to decide between repair and replacement of the damaged slings.
This is a guide that might help you determine when it’s time to replace those
damaged slings.
·
Deteriorated wires:
Five damaged wires in a strand indicate that it’s time for a replacement if you
are using single-part slings. If you’re using a multi-part sling, ten randomly
damaged wires in a rope lay should warrant replacement.
·
Metal loss: The loss of
metal may be indicated by the outer diameters of wires showing wear and tear
signs. In this case, you should strongly consider replacing the sling.
·
Bent and cracked end
attachments of wire rope slings should also warrant replacement.
·
Severe rope corrosion
is a sign that you should replace your slings. However, light rusting will only
reduce the strength of your slings. In this case, whether you replace them or
not is entirely up to you.
·
Bent hooks: The
standard throat opening is 15%. Once the hooks start to become bent, you should
consider replacing them.
· Chain and components wear should never exceed 10% of the original dimensions.
·
Once a chain sling has
been overloaded it must be taken out of service.
·
Store chain sling on a
properly designed rack. Never leave chain slings on the floor where they may
suffer atmospheres.
·
Chain slings must not
be heat-treated, galvanized, plated, coated or subject to any process involving
heating or pickling. These processes can have dangerous effects and will
invalidate the manufactures certification.
MAINTENANCE OF HOOKS
A
lifting hook is a device for grabbing and lifting loads by means of a device
such as a hoist or crane. A lifting hook is usually equipped with a safety
latch to prevent the disengagement of the lifting wire rope sling, chain or
rope to which the load is attached.
Maintenance
of Hooks
1. Before
use, hooks must be inspected by an experienced person.
2. Remove
a hook from service if any of the following are in evidence:
·
Cracks, nicks or gouges
·
Twist exceeding 10
degrees from plane of unbent hook
·
Damage or malfunction
to the latch
·
Throat opening
exceeding 15 percent
·
Wear exceeding 10
percent of original dimension
·
Damage from heat
·
Unauthorized repairs
3. Cracks,
nicks or gouges should be removed by a qualified person. Grind lengthwise,
following the contour of the hook.
4. If
removing the damaged area results in a loss of more than 10 percent of the
original dimension, the hook must be replaced.
5. Never
repair, alter or reshape a hook by welding & heating, burning or bending,
unless approved by the hook manufacturer.
6. When
lifting, ensure the hook, not the latch supports the load. The sling or lifting
device must always be seated properly in the bowl of the hook.
7. Never
side load, back load or point load a hook. It reduces strength and create an unsafe
condition
MAINTENANCE OF CLAMPS
A
clamp is a fastening device used to hold or secure tightly together to prevent
movement or separation through the application of inward pressure. There are
many types of clamps available for many different purposes. Some are temporary,
as used to position components while fixing them together, others are intended
to be permanent.
Maintenance
of Clamps
1. To
make sure the clamp works efficiently, it is important to keep all the parts
clean. Any dirt may damage the ability of the tool and stain the surface of the
work piece during clamping.
2. After
every use wipe the clamp with a dry cloth to clear any dust or debris that may
have built up.
3. Regularly
oil all the moving parts to keep them in best condition and to prevent rust.
4. Store the clamp in a safe and dry place, such as on a shelf in a garage
HEARING CONSERVATION PROGRAM IN PRODUCTION
INDUSTRIES
Hearing
conservation programs are designed to prevent hearing loss due to noise.
Hearing conservation programs require knowledge about risk factors such as and
ototoxicity, hearing, hearing loss, protective measures to prevent hearing loss
at home, in school, at work, in the military and, and at social/recreational
events, and legislative requirements.
a
hearing conservation program is required “whenever employee noise exposures
equal or exceed an 8-hour time-weighted average sound level (TWA) of 85
decibels’’. This means that employers are required to monitor all employees
whose noise exposure exceeds 85dBA during the course of 8 hours.
Benefits
of Hearing Conservation
Prevention
of occupational hearing loss benefits the employee by preserving hearing
abilities which are critical to good quality of life: interpersonal
communication, enjoyment of music, detection of warning sounds, and many more.
The HCP provides a health screening benefit, since non-occupational hearing
losses and potentially treatable ear diseases are often detected through annual
audiograms. Lowering exposure also reduces potential stress and fatigue. The
employer benefits directly by implementing an effective HCP, since workers will
remain more productive Effective HCPs can reduce accident rates and promote
work efficiency.
The
key elements of a hearing conservation program:
1.Noise
monitoring - this is measuring the noise levels in the workplace, the intensity,
or loudness, and the duration. You can use either:
-
area monitoring - measure the average levels in the workplace using a sound
level meter.
OR
-
personal noise (dosimetry) - the worker wears a microphone clipped on the
shoulder, near the ear, and exactly what they're exposed to all day is
measured, which gives a more accurate measurement of unprotected noise
exposure.
2. Audiometric testing - the annual hearing test
for all employees that are enrolled in the hearing conservation program. It has
to be done in an appropriate test environment, like an audio booth or a very
quiet room.
3.
Hearing protection selection and fit testing - the employer must provide
hearing protection in a variety of types with suitable attenuation
characteristics. Earplug fit-testing determines if employees are receiving
optimal protection for their noise environment, require additional training, or
need a different model of hearing protector. All the measured data can be collected,
stored, and uploaded to a cloud system for graphical display and analysis.
4.
Employee training and education -
training should include information on the effects of noise, information on
hearing protectors, an explanation of a hearing test, and information on the
hearing conservation program itself and what is expected of the employee for
the program.
5.
Record keeping – employers should document the workers’ hearing history. When
they first start the job, they should have a baseline hearing test, then an
annual audiogram after that to look for any changes. All these, along with any
evidence of training and education should be kept as a record, as well as any
fit-testing results or other relevant documents.
6.
Program evaluation - constantly evaluate
the performance of the program, by asking for employee feedback and reviewing
responsibilities and records.
KTU MODEL QUESTIONS
1. Which
are the hazards associated with manual material handling? (3 marks)
2. Discuss
the safety issues of Gas welding operations. (3 marks)
3. Which
are the various types of machine guarding devices used industries. Discuss the suitability
of each machine guarding devices. (14 Marks)
4. With
suitable sketches briefly explain seven defects of wire ropes. (14 Marks)
Dear Faculty & Students ,
Corrections will be done later with proper acknowledgement.
Thank you
Dr Manoj Kumar B