Material handling is defined as the transporting or supporting of a load by hands, bodily force, or by the help of machinery (like a crane, hydra, etc) is called material handling. Materials handling is one of the important functions in industries and other places. it involves:
- Method of handling, etc.
- Right from raw material to finished product materials are moved from place to place.
Importance of Material Handling:
- Material handling accounts for 24% of all employees, 55% of the space, and 87% of the production time.
- Cost of handling alone accounts for about 20-25% of total manufacturing costs.
- Each part is handled 50-60 times while it passes through the chain of manufacture.
- An average of 59 tons of material is handled for every ton of finished product.
- Material handling account for 21% of permanent disabilities and over 25% of temporary disabilities.
- Modern handling methods have improved safety.
Material handling involves:
- Increase in cost of the product by about 36%.
- For every one ton of finished product 50 -100 tons of materials are handled.
- Handling involves 20 – 28% of labor costs.
- About 60% of the manufacturing time is utilized for shifting the material from place to place.
- While shifting the material from place to place accidents are occurring which are about 40% of the total industrial accidents.
Types of material handling:
There are two types of material handling
- Manual material handling
- Mechanical material handling (Material handling via machine).
Manual handling is defined as the transporting or supporting of a load by hands or bodily force. This includes:
- Putting down
Injuries by manual handling :
- Back 45%
- Finger/thumb 16%
- Arms 13%
- Lower limbs 9%
- Rest of torso 8%
- Hands 6%
- Other 3%
Kinetics of manual material handling :
- Lifting and carrying exert strain on the body. By tensing muscles the body can be kept erect. Considerable effort is required even for walking on slopes or stairs.
- In manual materials handling human body acts as a machine (lever mechanism) and undergoes forces and torque. Due to this stress and strain occurs and if somebody does beyond his capacity faces pain, fatigue, and injuries.
- The lifting system of the spine can be represented as a double-armed lever arrangement in which the force of the back muscles is applied to the ends of the spine, which are about 5 cm long. According to the principles of levers, the force exerted by the back muscles must be 8 or more times the resistance represented by the load. The strain borne by the disc exceeds that exerted by the back muscles by an amount equal to the weight of the load. Lifting light load with jerks is also harmful and may cause spinal pain.
- Carrying loads imposes a static strain on muscles of the arm and trunk and also on the back and heart. Muscles are also engaged while holding the load and cause fatigue. Serious fatigue results in reduced output and may cause accidents.
- Careless and wrong manual load handling causes injury to the spinal column and adjacent muscles. It may also cause pulse rate rise, blood pressure rise, brain hemorrhage, abdominal hernia, and back pain. Therefore avoidance of excessive muscular efforts is of utmost necessity.
Manual handling responsibilities :
- Avoid handling where possible
- Conduct assessment
- Take steps to reduce risks
- Provide load information
- Make proper use of the equipment & follow safe working systems
- Co-operate with their employer
- Ensure others are not put at risk.
Manual handling risk assessments :
- Individual’s capabilities
Risk assessment in practice:
- Look for hazards
- Decide who might be harmful & how
- Evaluate risks/control measures
- Record the findings of the assessment
- Review / revise assessment
Manual handling Lifting techniques :
- Look at the load
- Foot position
- Bend knees/back straight
- Test load / take a firm grip
- Lift with legs/load close
- Put down with care.
Safe lifting techniques :
- As you may know, strains and sprains of the back are the most common.
Lift the right way :
- If possible use mechanical devices. If you must lift manually, remember – to avoid injury you should know both the wrong and right ways to lift.
These are the wrong ways :
- Back is unstable
- Leverage is poor
- The general burden is on back muscles, not stronger muscles, result – back is put under greater strain.
The right way :
- The back is erected and thus more stable.
Lifting is easier if load is already off the floor :
- Warning: Do not block up an object that topples easily.
- Lifting overhead is unsafe and should be limited to light objects. Even then follow these rules:
- Spread feet. Put one foot in front of another.
- Stand close to the place you will be putting the object.
- Keep objects close to the body.
Considerations for team lifting :
- All participants should be of similar height, build & gender
- One person should take control of the lift, command attention, inform others & co-ordinate the lift
- Double the people does not mean double the capacity.
If one person can lift 50 k.g :
- How much can two people lift? -only 70% or 70 kilograms.
- how much can three people lift? -only 50% or 75 kilograms.
Schedule factories rules :
|Person||Maximum weight for material article, tool or appliance|
|Adult male||55 kgs|
|Adult female||30 kgs|
|Adolescent male||30 kgs|
|Adolescent female||20 kgs|
|Male child||16 kgs|
|Female child||13 kgs|
Manual Material Handling (MMH) Checklist:
- Are the weights of loads to be lifted judged acceptable by the workforce? Yes no.
- Are materials moved over minimum distances? Yes no.
- Is the distance between the object load and the body minimized? Yes no.
- Are walking surfaces level wide enough? Yes no.
- Clean and dry? yes no.
- Are objects easy to grasp? yes no.
- Stable? yes no.
- Able to be held without slipping? yes no.
- Are there handholds on these objects? yes no.
- Is there enough room to maneuver? yes no.
- Are mechanical aids used whenever possible? yes no.
- Are working surfaces adjustable to the best handling heights? yes no.
Does material handling avoid:
- Movements below knuckle height and above shoulder height? yes no
- No static muscle loading? yes no
- Sudden movements during handling? yes no
- Twisting at the waist? yes no
- Extended reaching? yes no
- Is help available for heavy or awkward lifts? Yes no
- Are high rates of repetition avoided by job rotation? Yes no
- Self-pacing? yes no
- Sufficient pauses? yes no
- Are pushing or pulling forces reduced or eliminated? Yes no
- Does the employee have an unobstructed view of handling the task? Yes no
- Is there a preventive maintenance program for equipment? Yes no
- Are workers trained incorrect handling and lifting procedures? Yes no.
- “No” responses indicate potential problem areas that should be investigated further.
Manual material handling accesories:
- Hand truck and wheelbarrows.
Methods of handling different objects:
Boxes and cartons:
- Grasp them at opposite top and bottom corners. Draw a corner between the legs.
Barrels and drums:
Two men stand on opposite side. Grasp both chimes near the high point up and while pressing down the bottom and straighten up with the drum.
- Sheet metal:
handle with leather gloves, because of sharp edges.
- Handling on incline:
Use ropes and tackles. To control motion, pass a rope around a drum. One end of the rope fastened to the platform at a higher level. A worker keeps a firm grip on the free end, then gradually lowers or raises the drum.
- Sheet glass:
Handle with gloves or hand leather. Cover wrist and forearm with long leather sleeves. Leathers or canvas aprons and guards for feet and ankles should be worn. Carry the glass sheet with the bottom edge resting on a palm turned outward and with the other hand holding the top edge to steady or balance it. Never carry a glass sheet under the arm. Because a fall might sever an artery.
- Long objects:
Long pipes etc. should be carried over the shoulders, with the front end held as high as possible to prevent striking other employees especially at corners.
- Metal scrap:
Wear goggles, gloves or hand leathers, safety shoes, and skin guards. Workers should be cautioned about transferring the scrap. Mechanical handling of this commodity (magnetic lift crane) is preferable.
Storage and handling of specific materials:
- Crossties with mouth inside.
- When the pile is 5 feet high, step back by one row for each additional 3 feet.
- Do not remove a bag from a lower row first.
Pipe and bar stock:
- Consider the strength of the floor.
- Pipe in layers with strips of wood or iron between layers.
- Strips should have blocked at one end.
- Bar steel stock would be stored in racks inclining towards the back.
Barrels and kegs:
- The pyramid shape is safer.
- The bottom row should be blocked.
- If piled on ends, planks should be laid between rows.
- Portable containers such as drums & barrels should be stored and handled carefully.
- Storeroom walls should be impervious and provision for safe disposal of spillage on the floor.
- Before handling check corrosion of nails or weakening of packing by the chemical.
- For transporting use a trolley.
- Cylinders may be rolled on the bottom edge but never dragged.
- Carry the cylinder in a cradle or in a suitable type of carrying device.
- Do not permit them to strike each other.
- When not in use or while returning the empty cylinders, close the valve and replace the valve protection cap.
- Always consider cylinders as full & handle them with care. Do not store them in the sun or excess heat.
Handling of dangerous substances / chemicals:
- Dangerous substances should be handled and stored under the supervision of a competent person who is familiar with the risks.
- The workers handling them should be provided adequate information for their nature & handling procedure.
- Workers handling harmful substances should thoroughly wash their hands and face before taking any food or drink.
Floor conditions as per work:
- Absolute cleanliness.
- Absorptive qualities.
- Marking for stockings.
- Color code.
- Non-sparking of static disseminating properties and
- Durability will give a great effect on manual handling.
Lighting, ramps, obstructions, ladders, bridge plates:
- The required levels of illumination for the job must be available.
- Ramp’s gradient should not exceed 1 in 10. it should not be slippery, uneven, or broken. It should have sufficient width.
- Pipes, conduits, etc. so placed that they may cause minimum interference.
- Do not stand on stockpiles, use ladders.
- Bridge plates should be of adequate strength and they should be anchored properly.
Safety precautions while manual handling:
- The horizontal plane should be considered for the movement of material. Pushing and pulling are preferable to lifting and lowering.
- Lifting and lowering should be between hip and shoulder height and it should be close to and in front of the body.
- The material should be within limits and safe to grasp. It should not have sharp edges and corners etc.
- Material from the container should be easily removable. Chemical containers should be closed properly.
- If the load is too heavy, use mechanical lifting devices or take help from somebody.
- Get the load and feet close to the body. Lift by straightening the legs. Stand in a stable position in the direction of movement.
- Material temperature and floor condition should be comfortable.
- Use proper personal protective equipment while manually handling the material.
- Before lifting the material, the hands and the material should be free from oil and grease.
- Do not lift or lower the load by twisting the back or bending sideways or by extending the arms.
The effects of floor and lay out conditions on material handling:
- Depending upon the load and type of operations, the condition of the floor such as:
- Floor cleanliness
- Absorptive qualities of the floor
- Marking of the floor
- Colour of the floor
- Non-sparking or static disseminating properties of the floor and
- The durability of the floor produces a great effect on material handling.
- The floor used for stacking should be of sound construction, well maintained, leveled, and facilitating drainage. The ground should withstand all weather conditions. Stacks should not be close to railway tracks or in the vicinity of vibrations or the possibility of fire.
Ergonomics of Manual handling and Storage:
- Psychology, physiology, biomechanics, anthropology, and engineering are the main disciplines considered in ergonomics. Work physiology takes into account capacity for physical work, heart rate at work, matching people and their work, work-rest cycles, and fatigue.
- Anthropometrics is the measurement of the physical characteristics of humans, particularly length and weight measures; used for industrial design, especially the design of furniture, vehicles, and workplace. In computer use, such measurement applies primarily in the design of input and out-put devices, computer desks and chairs, and in the application of recommended working postures. The typical goal is to understand not just the average measurements of, for example, arm lengths and joint rotation angles, but to understand the range of possible variation within the target user population to adequately support the full range of users, from children to aging adults, and including both male and female dimensions.
- Anthropometry measures human body dimensions for work and biomechanics explains the strength of the human body in mechanical terms. It considers muscle strength and its method of working. It is this muscular strength that is mainly used in manual material lifting and handling.
- Four keys for ergonomics of manual material handling are as follows:
- Improved facilities of good layout provide the safe and efficient material transfer.
- Job or task design should consider stress on the worker and should decide whether to assign certain tasks to a person or machine.
- Selection, use, and improvement of equipment, machines, and tools strongly affect material handling requirements. Space requirement, control device, visibility, color and sound coding, etc. should be considered.
- The system must be designed for people as they are kingpins of material handling. Their body size, strength, and energy capabilities should be considered.
- These four keys provide a systematic analysis of material handling problems and many of the risks and strains can be avoided or reduced by intelligent job design, selection and use of equipment, and well-designed facilities.
Mechanical Handling of Materials
- In the case of mechanical handling, different types of mechanical equipment are used. All these heavy machineries are handled by man only. Again the method of operating this equipment depends upon the persons who are operating the equipment.
- Lifting machinery (Cranes, Elevators, Conveyors, Dumpers, Pay loaders, etc.) – safety aspects considered during design, construction, and testing of lifting machinery – training of operator on safe operation, signaling, inspection, and maintenance of Lifting Machinery.
- Power trucks and tractors, safety features in design and construction, safe operation, inspection, and maintenance.
- Chain slings, (fiber and wire) rings, hooks, shackles, swivels, eye-bolts – salient safety features. Calculation of safe working load; testing of lifting tools and tackles with reference to relevant IS codes and provisions of Factories Act and Rules, work of competent persons.
Material handling equipments:
- Lifting machines:
- Chain pulley blocks.
- Jib cranes.
- Lifting tackles:
- Lifting clamps.
- Wire rope sling.
- Chain sling
- Fork lifts.
- Power trucks.
- Conveyer belts etc.
Overhead traveling cranes:
- In the use of overhead cranes, great care should be taken for the safe & adequate means of access. It is necessary that all ladders and steps should be provided with secure handholds and tool holds.
- Proper landing or stages should be provided at the point of transfer from the ladder to the driver’s cabin.
- Effective means should be arranged to prevent a crane from traveling into the danger zone. Ensure that the crane is not approaching within 6 meters of the dangerous zone.
- A jib crane means a stationary or mobile crane in which suspension rope is supported by a projecting horizontal or inclined member known as a jib. The SWL should be marked on the jib. Automatic indicators are provided for SWL.
Bridge or Gantry Cranes:
- These are run on rails at ground level.
- Gantry cranes have short spans.
- Bridge cranes may have spanned up to 100 meters or more. They are used for handling coal or ore.
- Sweep guards on nip between rail and wheels, rail clamps to prevent movement due to wind and pressure, the safe height of electric contact rails, and operators cabin should be fireproof and weatherproof.
- 1-meter side clearance with the truck wheels of gantry cranes, skew switches to prevent excessive distortion of the bridge, etc. are some of the safety measures to be taken for the control of accidents.
- This system consists of one or more independent trolleys supported from or within an overhead track from which hoists are suspended. Monorail hoists are used to raise, lower and transport materials.
- They are of three groups:
- Hand operated.
- Semi hand operated.
- Fully power-operated.
- Rail stops at the ends of monorail tracks are desirable.
Crabs and winches:
- These may be hand-operated or electrically driven.
- Portable crabs and winches must be securely anchored against the pull of the hoisting rope or chain.
- A dog to lock the gears and a break or safety lowering devices, crankpin, and gear guards are necessary.
Pulley blocks or chain hoists:
- These are spur and screw geared and differential chain hoists. They may be portable, portable but permanently hooked onto a monorail trolley or built into the trolley as an integral part. They are suitable for many operations on which a block and tackle fitted with manila rope is used & are stronger and more dependable than rope tackle.
- The spur geared type is most efficient. Screw geared & differential hoists are self-locking to automatically hold a load in position.
- Load-carrying parts should be made of steel.
- The main types are stiff-leg, A-frame, gay, gin pole, and the breast derrick.
- With all the derricks, every part should be firmly anchored.
- Sticking from mast, boom, pulley block, and swivel hook should be prevented.
- Lifting tackles means, fiber rope sling, wire rope sling, chain slings, hooks, shackles, and similar gears.
- Generally, manila and sisal ropes are used in handling or hoisting and lowering operations.
- Periodical inspection of the whole length of wire rope is necessary to detect broken wires, amount of wear, corrosion, rust, etc.
- For the same working load, the chain sling is 5 to 8 times as heavy as wire rope but it has a longer life, can withstand rough use, and is almost 100% flexible.
- The standard hook is either of a circular section or trapezoidal. The circular section is meant for light loads up to 5 tons.
- Shackles are known according to their shape as D or Bow shackles. The pins are usually of circular section. Pins are secured by means of a nut and a cotter pin.
- All slings, rings, hooks, shackles, swivels, couplings, sockets, etc. should be made as per Indian standards.
- All tackles should be thoroughly checked before use.
- According to Factories Rules, no lifting machines, chains, ropes, and lifting tackles should be taken into use unless it has been tested and all parts have been thoroughly examined by a competent person and a certificate of such examination specifying the safe working load is obtained.
Testing of hoists, ropes and lifting tackles :
- All lifting machinery, hoists, ropes, and lifting tackles and gears must be tested before being taken into use for the first time or which have been lengthened, altered, or repaired by welding or otherwise.
- The purpose of the proof load is to subject the gear to a load in excess of the safe working load (SWL).
- The proof load test has to be done by a competent person.
|Safe working load||Proof load|
|Up to 20 tons.||25% in excess of SWL.|
|Exceeding 20 but not exceeding 50 tons.||5 ton in excess of SWL.|
|Over 50 tons.||10% in excess of SWL.|
|Hand operated chain pulley blocks.Chains, rings, hooks, shackles, swivels.||50% in excess of SWL.Twice the SWL.|
|Single sheave pulley blocks.||Four times the SWL.|
|Multiple sheave pulley blocks up to and including 20 tons, 40 tons and over 40 tons.||Twice the SWL. 20 tons in excess of SWL. 50% in excess of SWL.|
Uses of main mechanical handling equipment are given below:
|Electric Overhead Traveling crane(EOT)||Lifting, shifting, and placing any where in the traveling area.|
|Jib crane (mobile), Gantry crane||Lifting and shifting at desired places|
|Power trucks||Three or four wheeler truck to pick, hold and carry (transport) material. Useful in making piles, stacking and un-stacking.|
|Conveyers||Transporting / carrying material between two fixed points. Useful as a feeding device where manual feeding is un-safe.|
|Lifting tackles||they are rings and slings (chain or rope, metal or fiber), hooks, shackles and swivels. They are used to connect load or container to any lifting device.|
|Fork lift truck||It is a power truck having projecting fork to pick, hold, carry and unload (replace) the material or container. May be power driven or battery operated. Conveniently used on smooth floor.|
|Pay loaders, power shovels, winch crab, pullers and hydraulic/pneumatic jacks||Used to dig, lift and transport heavy material. Well trained operators, supervision and good maintenance are necessary.|
|Lifts and elevators||Moves vertical, horizontal or in any unilateral direction (cable path) between two fixed points, lift vertically and carry material or persons. A cage or cabin must travel in a fixed path and well enclosed. Interlocked doors / gates essential.|
|Hoists||Electric, pneumatic and hand operated types of chain hoists are used. Chain hoists are spur, differential or worm drive.|
|Mono-rails||Should be well supported on both ends like a hanging bridge. The chain pulley block or hoist mounted on it should move freely.|
- Industrial power trucks usually operate on storage batteries or internal combustion engines and are extensively used in factories for handling of materials to and from stock piles or loading platforms.
- These trucks are of many types, such as fork lift type etc.
Fork lift truck:
- The forklift truck makes the lift by means of a two-prong fork instead of a platform and lifts the load up from the floor permitting high piling to conserve space.
- They could also be fitted with special attachments for handling barrels, paper reels, etc. safety precautions to be observed in the operation of forklift trucks are:
- The capacity of forklifts should be marked on the truck body and they should not be overloaded.
- Loaded or empty forks should be carried as low as possible but should not strike a ramp.
- Care must be taken to avoid jerking when tilting a load forward or backward, especially when the load is at a height.
- Nobody should be allowed to ride on the forks.
- Forks should be driven well under the load, preferably full length or at least 2/3 of the length.
- When there is a danger of falling objects over the operator, a canopy guard should be provided.
- Aisles, floor, etc. should be maintained in good condition including proper lighting.
- The entire conveyor mechanism must be inspected regularly. If any part is found worn-out, it should be immediately repaired/replaced. Attention should be paid to brakes, backstops, anti runway devices, overload releases, and other safety devices.
- All machine parts should be lubricated as per the instruction manual of the manufacturer.
- Gears, sprockets, sheaves, and other moving parts must be protected by guards or other means to protect against personal injuries.
- Various types of conveyors are used in many industries to eliminate manual labor, to expedite the movement of materials, and also to facilitate the processing or assembling.
- Belt conveyors are widely used and they are of a flat or troughed type and can be horizontal or inclined.
- They are used for handling almost all the materials of the modern industry including coal, coke, grain, and building materials such as sand and gravel
- Electrical and mechanical interlocking devices should be provided to stop at the time of requirements.
- Emergency stop devices should be located very near to the conveyors.
- Overload protection devices must be provided.
- If repaired due to overload, the entire conveyor should be inspected again.
EOT cranes operation & maintenance:
- Do not use a crane if you are not an authorized operator.
- When in crane cage ready for prompt service.
- Never go on top of the crane or permit anyone else to do so without opening the main switch and placing a warning sign on it or locking it.
- Before moving the crane bridge, be sure the hook is high enough to clear all obstacles.
- Under no circumstances permit your crane to bump into another crane.
- Examine the crane in every shift for loose or defective gears, keys, railings, warning bells, signs, switches, sweep brushes, cables, and other parts. Report defects. Keep the crane clean.
- After the repair job, make sure all loose materials have been removed, so that nothing can fall once the crane started.
- Do not carry a load over men, siren when necessary. Do not allow men to ride on a crane hook.
- If the power goes off, move the controller to the ‘OH’ position until power is again available.
- If the extinguisher is kept inside a crane see that it is in good condition.
- Do not operate the crane if you are not fit.
- Do not drag slings, chains, or cables.
- If you feel something is not safe immediately inform the in-charge concerned.
- When you leave the cage open main switch.
- When you part an outside crane at the end of the shift, set the brake or chain the crane to the truck.
- Stop operation and open the power switch if your carers fail to respond correctly. Attempting to get out of the difficulty by repeated operation may make the condition worse.
- 17.When lifting a load with a chain pulley block you should see that the anchor can stand the load to be lifted. There are chances that anchorage may not be strong enough to stand the load up to the lifting capacity of the chain pulley block. Also, defects in hooks and shackles to be checked (figure below).
Lifting machine / tackle:
- To achieve smooth movement safety plays a very important role.
- To achieve the desired load movement lifting appliances are used.
- Every lifting machine and tackle should bear the following markings:
- Identification mark or number (relating to the test certificate).
- Safe working load.
- Date of the proof load test. (Stamping)
- The lifting machines and tackles not bearing these marks should not be used on the shop floor.
Classification of Material handling Equipment:
1. Lifting Equipment:
- Hoists and Lifts
- For men
- For material
- Lifting Machines
- Pulley blocks
- Overhead crane
- Lifting Tackles
2. Transport Equipment:
- Mobile crane
- Tyre mounted
- Industrial trucks
- Tractor trailers
- Hand-lift trucks
- Wheel barrows
- Slat and apron
- Live roll
- Pipelines and
- Mechanical shovels
- A lifting machine means a crane, crab, winch, travel, pulley block, gin wheel, transporters, or runway.
- Lifting tackle means any chain sling, rope sling, hook, shackle, swivel, coupling, socket, clamp, tray, or similar appliance, whether fixed or movable, used in connection with the raising or lowering of persons or loads by use of lifting machines.
Selection criteria of equipments:
- Depending upon handling condition, place, and type of material the equipment are selected considering the following safety points:
- Safe working load of the equipment.
- Control points.
- Emergency control.
- Indicators of various pressure.
- A clear view of the driver.
- Proper means of access to & from equipment.
- Ease in operating the control points.
Safety points for the operators:
- Know the safe working load (SWL) of the equipment.
- Before starting the work check the engine, oil, radiator, brakes, steering, tire pressure, etc.
- Check your visible signs of damage, run your eyes all around, clear the obstructions or rubbish which may be a fire hazard.
- While working if any defects are found, do not try to rectify yourself keeping the equipment in running condition. Do not continue to work with faults, stop the work and report about them immediately.
- Try to work on level sites, avoid working on slopes, it increases the danger.
- Only move the load when you can see it. If you can not see the load use a competent signaler.
- Do not travel or hang loads over people’s heads and keep the empty hooks high.
- ‘Feel’ a load before you lift it. Avoid ‘snatching’ loads up or dumping them down.
- Avoid excessive traveling with loads, or with cargo gear handling on the hook.
- Do not lift loads until all personnel is clear, particularly when working with wagons or lorries.
- Do not allow to ride on crane hooks, spreaders, or slings.
- Do not allow ropes to become slack when depositing loads, and leave the crane with the load suspended.
- In case of any failure, stop the operation report and do not operate until the clearance is given by the competent person.
- Do not leave any flammable material in the cabin and keep the cabin clean and tidy.
- The maintenance staff is responsible for the mechanical and electrical maintenance of the cranes/equipment and hence no unauthorized person is allowed on the crane.
- It is your responsibility to lift and carry all loads safely. Insist on safe slinging and do not lift unsafe loads.
- When parking your crane at the end of a work period, keep well clear of roads, railways, and working ways.
- Leave the crane with:
- The jib up and the cab locked in the fare and appropriate place.
- The hand brakes on.
- The hook well up, clear of people and traffic.
- All controls in the neutral or off position.
- The key removed.
- SWL stands for the safe working load.
- Safe Working Load is the limiting safety factor to lift and carry any load safely. It must be clearly marked on any lifting device like hoists, lifts, lifting machines, and tackles.
- “The maximum safe working load shall be plainly marked on every hoist or lift, and no-load greater than such load shall be carried thereon.”
- “No lifting machine and no chain, rope or lifting tackle shall except for the purpose of the test, be loaded beyond the safe working load which shall be plainly marked and duly entered in the prescribed register, and where this is not practicable, a table showing the safe working loads of every kind and size of lifting machine or chain, rope or lifting tackle in use shall be displayed in prominent positions on the premises.”
Calculation of SWL:
Minimum breaking load quoted by manufacturer
SWL = —————————————————
Factor of safety
- For wire ropes, Factor of safety is 6 for general purpose and 7 for heavy industry.
- A thumb rule formula of SWL = (wire rope diameter)2 x 8 kgs.
- For example: for 12 mm dia wire rope SWL = 12 2 x 8 =1152 kgs
Hoists and lifts:
- Every hoist or lift shall have the safe working load plainly marked on it and no load greater than such load should be carried on it. The cage of every hoist or lift used for carrying persons should be fitted with a gate on each side from which access is afforded to a landing and such gates should be fitted with interlocking or other efficient devices to ensure that they cannot be opened except when the cage is at the landing and the cage can not be moved unless all the gates are closed.
- Every hoist and lift shall be of good mechanical construction, sound material, and adequate strength, properly maintained and examined by a competent person at least once every six months.
- Wherever the cage is supported by rope or chain, there shall be at least two ropes or chains separately connected with the cage and balanced weight and each rope chain with its attachments should be capable of carrying the whole weight of the cage together with the maximum load.
Testing, Inspection and maintenance:
- Tests for satisfactory operation of each controller, switch, contactor, relay, interlocks, the sequence of operation, protective devices. Tolerance on specified speeds at full load shall be within 10%.
- Overload test by 125% of the working load. Proof test load may vary from 1.5 to 4 times of the SWL. A sample of wire ropes should be tested.
- Periodic inspection to detect unsafe conditions, worn or damaged parts, wear, and other defects in wire and fiber ropes, lifting gear, etc are necessary.
- Gear wheels and pinions should be maintained in good condition, properly keyed, and in their correct gear mesh.
- Gear wheels and pinions with broken teeth or cracked areas, rims, or bosses should be discarded and replaced.
- The faces of all ratchets, jaw clutches, gear locks, and collars should be kept in their correct relationship to ensure safety in use.
- Repairs shall be carried out through the ‘permit to work procedure.
- Notices like ‘under repair’, ‘out of order’, ‘don’t start’ etc. should be displayed.
Care, Testing, Inspection and maintenance of lifting Machines and Tackles:
|1.Appropriate factor of safety. |
2.Sound material and good construction.
3.safe design marking of SWL and identification.
4.Provision of limit switches, brakes, anchoring, ear-thing, guarding, means of access, ladders etc.
|1.Trained operator. |
2.No loading above SWL.
3.Moving hook load safely.
4.use signaling and warning.
5. Raise or lower carefully.
6.Following manufacturer’s instruction.
7.Work on or near tracks.
8. No load handling over workers on floor.
9.Safe position at the end of work.
|1.Periodical tests and certification.|
2. Lubrication of parts.
3.Repair and replacement of parts.
4.Daily and periodical inspection.
5. Display of notices and load tables.
Inspection of Tackles:
|Hoisting and lowering wire rope||3 months|
|Wire rope with broken wire||1 month|
|Cranes and attachments||12 months|
|Thorough inspection of all parts of the crane||3 years|
|All other lifting machinery||12 months|
|Half inch and smaller gear||6 months|
The signaler must stand on a secure position where he can see the load and be seen clearly by the driver. Each signal must be distinct and clear.
Hzards of Material Handling
1.Hazards of manual material handling
- Carrying excessive load.
- Lifting improperly.
- Unsafe gripping or placing.
- Struck by the falling body or striking against an object.
- The person falling or slipping.
- Failure to wear personal protective equipment.
2.Hazards of mechanical material handeling:
- Wrong selection of equipment.
- Design defect or unsafe construction or operation of equipment.
- Overloading of equipment.
- Wrong position of material or equipment.
- Working at excessive speed.
- Lack of space for operation.
- Lack of skill, training, and correct attitude on the part of the operator.
- Improperly guarded or unguarded machinery.
- Electrical faults and.
- Poor maintenance or no testing.
- The toppling of the crane.
- Failure of the boom.
- Failure of sling, rope, chain, etc.
- Struck by moving machine.
- An object falling from a height.
Duties of the Competent Person for marterial handling:
- To study the provisions of the Factories Act., Rules, and other statutes pertaining to hoists, lifts, lifting machines, and tackles.
- To study Indian Standards and other relevant codes for design, operation, maintenance, testing, and certification of material handling equipment.
- To go on call to the manufacturers and users of the material handling equipment to test and certify them.
- To keep ready the necessary load testing, heat treatment, NDT, and other equipment to test the machine parts.
- To report the defects to be rectified to the user/customer and to the concerned authority.
- To keep ready the necessary statutory forms to be filled after the statutory examination or testing.
- To test and certify again after the rectification of the defects previously noticed.
- To get renewed the certificate of competency issued by the authority.
Responsibilities of the Competent Person:
- To calculate the SWL where it is not available.
- To prepare a table of SWLs and load angles in case of a jib-crane or multiple slings – where SWL varies at different angles of the jib or legs and to display near the machine.
- All hoists, lifts, lifting machines, and tackles shall be thoroughly examined and tested and a certificate in the prescribed form shall be signed specifying the SWL and defects found if any, and given to the user.
- Different types of load tests including the deflection test of an overhead crane shall be carried out and certified.
- Different types of defects shall be ascertained and remedial measures shall be suggested to remove them.
- Defective, lengthened, altered, or repaired by welding or otherwise parts shall not be used again unless it is adequately tested, examined, and certified in writing by the Competent Person.
- The heat treatment process of the parts shall be carried out under the supervision of the Competent Person.