Home » Mechanical Engineering » ACCIDENTS AND THEIR TYPES


The accidents are the mishaps leading injury to man, machines or tools and equipment and may cause injury and result either death or temporary disablement or permanent disablement of the industrial employees. A survey was conducted in 1952 in America which specified that approximately ten thousands industrial persons were killed in accidents and more than lakhs were injured in a year. The accidents are unwanted events or mishaps that result in some sort of injury to men, material, machines, tools, equipment and semi or finished product hence, a loss to the whole establishment. The total cost of these accidents was more than crores of dollars. An industrial accident may be defined as an event, detrimental to the health of man, suddenly occurring and originating from external sources, and which is associated with the performance of a paid job, accompanied by an injury, followed by disability or even death. An accident may happen to any employee under certain circumstances. The said injury or loss may be minor or major in nature and accordingly the accident is termed as non- reportable or reportable kind. It should, however, be understood that no hard and line of demarcation can be laid between these two aspects and their identification varies with the place of application. For example a small burn or cut oft body will be reportable accident in a workshop whereas the same, can be treated by first aid and does not involve any appreciable loss of time, not be considered a reportable accident. Few industries determine the accidents by the extent to which it leads to the disablement of the victim and number of hours or days he is to remain absent from duty on account of the problem. There are others which take into consideration various factors like machine, tools, materials, cost of medicines, loss of production and compensation to be given to the worker who meets with the accident. An accident can be very costly to the injured employee as well as to the employer of the manufacturing concern. Some direct or indirect costs are associated with accidents in industries. The direct costs involve payment of compensation and overheads uncompensated wage losses of the injured employees, cost of medical care and hospitalization. Whereas indirect costs of an accident comprise of costs of damage of machines, materials and plant equipments, costs of wages paid for time lost by workers not injured, costs of wages paid to the victim, costs of investigating agency involving recording and reporting of accidents and its causes, costs of deputing new employee for replacement of the injured employee, cost of decreased production by the substituting victim, cost of delays in production due to accident, cost of reduced efficiency of the victim when he joins the manufacturing concern after getting recovered and cost of lowered production due to reduced morale of employees. An accident is an unexpected event which is likely to cause, an injury. Proper diagnosis of causes of mis- happening and corrective measures of the same always helps in preventing future accidents. Accidents in industries put a heavy burden on society also. All direct and indirect cost to the management will ultimately have to be met by the consumers in terms of increased cost of product. Also, the financial burden of disabled persons and their dependents have to be born by society. Thus every citizen in a nation has to bear a proportion of the cost of accidents. Every care and prevention therefore should be evolved adopted to prevent accidents to the maximum possible extents. Accidents do not just happen but they are caused because of failure to follow the needed safety precautions and safety rules. If someone is honest with himself, he cannot think of a single accident that could not have been prevented by care.

There are various types of common accidents needing due attention to prevent them which are as follows:

1. Near Accident An accident with no damage or injury is called near accident.
2. Trivial An accident with very less damage is called trivial.
3. Minor Accident It is an accident with damage and injury more than trivial.
4. Serious Accident An accident with heavy damage and lot of injury is called serious accident.
5. Fatal It is an accident with very heavy damage. There may be loss of lives also.

Effect of Accidents

The adverse effects of the accident are given as under—

(A) Effect on the owner of factory

(i) Direct cost of an accident

1. Cost of the compensation paid to the workers.
2. Cost of the money paid for treatment.
3. Cost of the monetary value of damaged tools, equipments and materials.

(ii) Indirect cost of an accident
1. Cost of the lost time of injured worker.
2. Cost of the time lost by other employees.
3. Cost of the delays in production.
4. Cost of the time lost by supervisors, safety engineers etc.
5. Cost of the lowered production due to substitute worker.

(B) Effect on worker

1. The industrial workers may get temporary or permanent disability.
2. If the industrial worker dies, his family loses the earner and the compensation never equals to his earnings.
3. Accident also affects the morale of the employees working in the manufacturing environment.

(C) Effect on society Work connected with injuries put a considerable burden on society also as given as under:
1. Cost of accidents is included in the products, so the society has to pay more prices for the industrial products.
2. If some industrial workers do not come under compensation act, the need for help from society is much greater.
3. Loss of production hours may causes fewer products in market. So more prices if demand is more than production.


The accidents may take place due to human causes, environmental causes and mechanical causes. These causes are discussed as under.

Human Causes
1. Accidents may occur while working on unsafe or dangerous equipments or machineries possessing rotating, reciprocating and moving parts.
2. Accidents occur while operating machines without knowledge, without safety precautions, without authority, without safety devices.
3. Accidents generally occur while operating or working at unsafe speed.
4. Accidents may occur while working for long duration of work, shift duty etc.
5. Accidents commonly occur during use of improper tools.
6. Accidents may occur while working with mental worries, ignorance, carelessness, nervousness, dreaming etc.
7. Accidents occur because of not using personal protective devices.

Environmental Causes
1. Accidents may occur during working at improper temperature and humidity causes fatigue to the workers so chances of accidents increases with workers having fatigue.
2. The presence of dust fumes and smoke in the working area may causes accidents.
3. Poor housekeeping, congestion, blocked exits, bad plant layout etc. may cause accidents.
4. Accidents occur due to inadequate illumination.
5. Improper ventilation in the plant may also leads to industrial accidents.

Mechanical Causes
1. Continued use of old, poor maintained or unsafe equipment may result in accidents.
2. Accidents commonly occur due to use of unguarded or improper guarded machines or equipments.
3. Unsafe processes, unsafe design and unsafe construction of building structure may lead to accidents in the plant.
4. Accidents occur due to improper material handling system and improper plant layout.
5. Accidents may occur due to not using of safety devices such as helmets, goggles, gloves, masks etc.

However the other general causes of accidents in workshops are listed under:

1. Because of ignorance to work with equipments, hand tools, cutting tools and machine tools.
2. Operating machine and equipments without knowledge.
3. Extra curiosity to work without knowing.
4. Due to poor working conditions.
5. Because of speedy work.
6. Improper method to work.
7. Due to use of improper tools.
8. Because of lack of discipline.
9. Uninterested in work.
10. Due to carelessness.
11. Due to over confidence.
12. Bad working environment.
13. Because of excessive over times duty by industrial workers.
14. Dangerous materials with which to work.
15. Lack of cleanliness.
16. Due to poor planning.

In a conducted survey, it was observed that most of the accidents, to the tune of 98%, could be easily avoided provided due precautions and care were adopted well in time. It was stressed that accidents do happen but are caused due to the failure of one element or the other. The most unfortunate and most common factor in occurring accidents is the human element which occurs due to non-observance of the safety measures or safety rules. The past statistics also reflects that the causes of accidents as well as the nature of accidents depend entirely on the extent to which safety measures are adopted and not the manufacturing processes or operation. The common causes which lead to accidents may be improper acts by industrial personnel which result in violation of safety rules and non -observance of safety precautions, due to improper tools, machinery and equipments or their unsafe or improper use due to unsafe working position and unsafe working conditions in manufacturing areas. Some major factors namely technical, unsafe working conditions, mechanical, environment, human cause, unsafe acts and other personal factors are most responsible for accidents. Technical causes or unsafe conditions involves deficiencies in plant, equipment, tools, machinery, materials handling system, general work environment etc. Mechanical causes involve unsafe design and construction of tools and devices, cutting tools, machines tools and mechanical equipments, hazardous arrangement such as piling, over-loading etc, improper guards a against dangerous machine components, defective tool and equipments, improper material handling, leaking valves of acid and poisonous gases, and use of untested boilers and pressure vessels. Environmental factors indicate improper physical and atmospheric surrounding conditions of work which indirectly promote the occurrence of accidents These factors include too low temperature to cause shivering, too high temperature to cause headache and sweating, too high a humidity (in textile industry) to cause discomfort, fatigue and drowsiness, inadequate illumination causing eyestrain, glares, and shadows, presence of dust, fumes and smokes in
industries such as foundries, chemical , paper and sugarcane etc. Lack of adequate ventilation, high speed of work because of huge work load, more number of working hours and over and above them the tendency of the employer to insist for over time work, inadequate rest periods in between works, noise, bad odor and flash coming from the nearby machinery, equipment or processes, and poor housekeeping are also personal factors. A large number of accidents can be avoided if proper safety measures and safety rules are adopted in manufacturing areas. Some of the important causes of accidents involve violation of safety rules, not using of safety devices, improper use of gadgets and machine controls, non-development of safety working habits, ignorance of the operation of tools, machine and equipments operation, unsafe working conditions, monotony and work-relating stresses, wear and tear of the functional components, explosive and inflammable material etc.

A large number of revolving, rotating, reciprocating and moving parts of machinery can be said as the sources of danger and require guarding for protection against accidents. Extensive studies reveal that some characteristic groups of dangerous parts are acting as common sources of accidents in workshops.

Many such major sources are as under.
1. Revolving parts, viz. pulley, flywheels, worms, worm wheel, fan, gears, gear trains, gear wheels etc.
2. Projecting fasteners of revolving parts; like bolts, screws, nuts, key heads, cotters and pins etc.
3. Intermittent feed mechanisms, viz., tool feed of planer; table feed of a shaper, ram feed of power presses and similar other applications.
4. Revolving shafts, spindles, bars, mandrels, chucks, followers and tools like drills, taps, reamers, milling cutters, and boring tool etc.
5. Rotating worms and spirals enclosed in casings, such as in conveyors and revolving cutting tool, like milling cutters, circular saw blade, saw band, circular shears and grinding wheels, etc.
6. Reciprocating tools and dies of power presses, spring hammer, drop hammers, and reciprocating presses, reciprocating knives and saw blade such bow saw, shearing and perforating machines and the cutting and trimming machine and power hack- saws etc.
7. Moving parts of various machines, like those of printing machines, paper-cutters and trimmers, etc.
8. Revolving drums and cylinders without casing, such as concrete and other mixers, tumblers and tumbling barrels, etc.
9. High speed rotating cages such as in hydro-extractors.
10. Revolving weights, such as in hydraulic accumulator or in slotting machines for counter-balance.
11. Nips between meshing racks and pinions of machine parts
12. Nips between reciprocating parts and fixed components, such as between shaper table and the fixture mounted on it or a planer table and table reversing stops, etc.
13. Nips between crank handles for machine controls and fixed parts.
14. Projecting nips between various links and mechanisms, like cranks,  connecting rods, piston rods, rotating wheels and discs, etc.
15. Projecting sharp edge or nips of belt and chain drives; via belt, pulleys, chains sprockets and belt fasteners, spiked cylinders etc.
16. Nips between revolving control handles and fixed parts traverse gear handles of lathes, millers, etc.
17. Moving balance weights and dead weight, hydraulic accumulators, counter-balance weight on large slotting machines, etc.
18. Revolving drums and cylinders uncased, tumblers in the foundry, mixers, varnish mixers etc.
19. Nips between fixed and moving parts such as buckets or hoppers of conveyors against tipping bars, stops or parts of the framework.
20. Nips between revolving wheels or cylinders and pans or tables, sand mixers, crushing and incorporating mills, mortar mills, leather carrying machines, etc.
21. Cutting edges of endless band cutting machines, wood working, and log cutting metal find stone-cutting band saws, cloth-cutting band knives, etc.
22. Nips between gears and racks strips, roller drives, presses, planning machine drives, etc.


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