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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSWELCOME TO IIMSHE

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSIntroductionMostly all the industries use innumerable machines & these machines, no doubt, help a fast rate of production & at the same time reduces the human efforts required for producing but they are also responsible for a large number of accidents at work, which are usually & potentially more severe and some times very serious but are almost preventable in the context of hazards involved there in.

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Depending upon the way the harm is caused due to these accidents from machines can be classified into following groups:-ContactImpactTrapsEjection of ParticlesElectrical or Mechanical Failure

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Contact:

Physical contact of body with moving parts of the machine. Generally these lead to cuts and abrasion. e.g. hand touching a V-belt.

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Impact:

Parts of the body being violently hit by moving parts of machines. e.g. hit by the ram of a press or hit by the bed of a planer while travelling.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSTraps:

A part of body comes in between moving parts. This mostly lead to a crushing of the parts of body trapped. e.g. hand crushed in between the die & punch in a power press or between two rollers.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEjection of Particles:

Components or parts projected at high velocity from the machine. They cause serious injury when they hit the parts of human body. e.g. a spanner falling on a coupling is projected up and hits a worker or chips flying from machine lands in the eye of the operator.

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MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSElectrical or Mechanical Failure: Electrical or mechanical failure which results in a shock or injury to worker say belt breaking or pulley coming out while in motion. Some of the hazards remain with the machine and the job situation on a continuing basis and the operator is exposed to chances of an accident through out the operating time. Like operation of a power press without guard, machining of brass without eye protection and working near unguarded rollers are illustrative examples. Different from these are the occasional or contingent dangers arising out of machine failures, abnormal work situations or unexpected human errors. One should look into the such issues and identify both the continuing dangers associated with machine operation and contingent dangers that can be predicted.*IIMSHE*

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSLegal RequirementsAs per the Factories Act, the primary legislative requirements in respect of machine guarding are:

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEvery flywheel and every moving part of any prime mover shall be securely fenced.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEvery part of the transmission machinery shall be securely fenced unless it is in such a position or of such construction as to be safe to every person employed in the premises.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEvery dangerous part of any machine, shall be securely fenced unless it is in such a position or of such construction as to be safe to every person employed in the premises otherwise.

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MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS Secure fencing in this context can be interpreted as the use of proper guarding of the machines from the identified hazards and predicted dangers of causing accidents to be provided with the maximum degree of safety.In addition to such requirements set out in the Factories Act there are various regulations applying to specific machines, or unfenced machinery for example:The Woodworking Machines Regulations.The Abrasive Wheels Regulations.

More over requirements are placed in respect of the dangers present while cleaning the machinery and for the training and supervision of young persons working on dangerous machineries or performing dangerous operations.The requirements of the Health & Safety at Work and the Factories Act. also must be borne in mind when considering machinery safety.*IIMSHE*

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSMachine GuardingMachine Guarding is a term given to erecting a barrier or a system in between the operator and the machine with a view to protect him from specific dangers.

If the functions of the machine and the guard are understood by the designer, if the right guard is selected, and if it is installed correctly, protection of the operator can be ensured within the reasonable costs.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSFunctional Requirements Of A GuardThe guard should offer positive protection to the operator under all normal working conditions.It should offer protection to others nearby. A guard protects the operator in front but presents a danger to the operator of the nearby machine at the back cannot be considered acceptable.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe guard should not cause any danger by itself. One which shakes or rattles, one which annoys the operator or one which brings a fresh safety problem (like a pedal guard which extends to the gang-way) are also unacceptable.The guard should not interfere with normal operator movements, or functions like oiling adjusting etc.The construction of the guard should be rigid and sturdy and should be recognized as an integral part of the machine.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSImportant AspectsIn making machine operations safe, there are two distinct aspects which need consideration of following two factors:

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The Safety offered by machine itself: In terms of type of operation, exposed dangerous parts, accessibility of dangerous parts, probability of accident during normal operations, extent of severity in case of accident and the demands made on the operator for safe performance.

The operator himself: His knowledge, skill, understanding of danger, emotional status and performance.

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Any attempt to make machine operations safe, one should consider these above mentioned both the aspects together one in relation to other. Ideally, this work should begin at the design stage of the machine itself but this is not the practice always followed and the bulk of safe-guards and safety features are very often incorporated after the machine is built and in some cases, after it has been in use for a long time (or number of accidents have occurred). The safe-guards thus incorporated later on, fail in majority of cases partly due to their incorrect design and not being compatible with the machine functions and partly due to there unacceptability by the operators.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSTo make the machine operations safe a realistic study of the risk involved and the possible ways in which accidents can take place is most important feature, and thus in turn, calls for looking into a number of interrelated issues like:

Risk Involved

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe type of machine, the type of job handled by the machine, the functions performed by the machine and the limitations of the operations.The ways in which the machine operation can lead to injuries to persons, location of dangerous parts, there speeds, energy involved etc.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe severity expected in case of an accident taking place.A situation which can cause serious or fatal injury gets priority over one which leads to a nick.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe operator position & his movements. Is it necessary for him to reach dangerous parts? How often? Can he reach them even if it is not required as a part of his job? How easy or difficult it is for him to do so? How the danger is known? How obvious is it to the operator, to the supervisor, and to the layman?What are the uncommon situations the machine is likely to encounter? Defective material? Careless operators? Operator on incentive? Rush work? Is the risk enhanced under such conditions? To what extent?

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSWhat are the extra demands put on the operator for safe performance of machine? More skill? More alertness? More care? Physical strength? To what extent, the operator meets the demands?Can the job be made absolutely safe? If not, to what extent it can be done? What are the limiting factors? Can they not be overcome?

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSWhat are the different choices of safe-guards available? What degree of protection each gives? At what cost?Identify all possible chances of accidents including human errors and neglects.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSReduce the reliance on human element in operational safety to the minimum by increasing the reliability of the machine.Safeguard against human errors including neglect and willful misuse (like removing machine guards). The observation by Dr. Richard Booth that the unpredictable human behaviour should represent a challenge to the design skill of engineer and should not be smoke screen to misrepresent a careless or untidy design is more than correct.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSIdentify weak elements in the design itself (if any) and compensate them by specifying procedural safeguards, warning devices or supervisory action.Consider the operator in all aspects.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSTo make the machine safe by its design itself, such that they do not offer any scope for accident should be the first choice in ensuring safety in the machine operations. This work begins at the designers table. Apart from the machine functions and operations, the operator and his performance and the work situations should be studied & the safeguards incorporated in the design/operation of the machine should be such that operators are never exposed to danger. Incorporating safeguards in the design stage itself has many advantages like:

Design Criteria

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSDesign of safeguards are done by the same professional who designed the machine.The question of functional incompatibility between machine operation and safeguards does not arise.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThey work out cheaper compared to the safeguards incorporated later on.Since the safeguards arrive as a part of the machine, they have a greater level of acceptability from operators.

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Since safety standards can not be drawn which will cover every conceivable hazardous mechanical exposure, it is often necessary to use imagination and ingenuity to protect usual situations. If the basic hazardous actions and motions are understood, it is easier to evaluate the hazard and to develop effective control measures, what ever is the machine, involved with the type of action or motion there in.

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While doing the assessment of risk presented by a machine during every phase of its operation, the likely and forcible human behaviour must also be considered because the greater the risk from the machine and the more likely the possibility of abrupt human behaviour demanding the greater degree and as well as need to take every possible step in ensuring the safety by taking the following two factors into account while assessing the risk:The severity of forcible injuries; andThe probability of there occurrence.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe greater the possibility of injury or occurrence the greater the need to protect against it, and thus the greater should be the reliability of protection with the greater degree of safety.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSIn any machine system where its safety may be adversely affected by the failure of any single part, or the whole, than each component in the system must be considered in ordered to determine the probable potential of its failure modes and the consequences due to its failure.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSSafeguards built into a machinery should be designed and constructed in such a way that bypassing or defeating them either accidentally or deliberately is made impossible or difficult as possible.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSWhile doing the maintenance or modification of any machinery or system, it should be intended to preserve the design level of safety performance and where ever practicable these activities should intend to improve the overall safety performance.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSPlant layout & house keeping also play an important & crucial role in providing the good machine guarding for safe operations and safe working conditions, as making the machines safe alone is of little use unless the entire work area around the machine is also made safe like few conditions to mention below: e.g.

Role of Plant Layout & House Keeping

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS.A properly guarded power press installed in a confined space with tools, dies, sheets and scrap scattered around can not be considered safe.A correct lay out which permits adequate area for the free movement of the operator, sufficient space for material before and after processing and provision for collection and disposal of scrap are also essential for ensuring the safe operations.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe relative position of the machine with respect to aisles and traffic, movement of material, welding and other jobs near by (which can obstruct the operator) are important considerations and need to be looked into.General cleanliness, orderliness and house keeping around machine are no less important aspects.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSNever the less the another unsaid area is of machine maintenance, which has an indirect but definite relation with safety performance of machines and machine guarding. There are three ways in which safety and maintenance are linked.

Silent Feature of Maintenance & Machine Guarding

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSAccidents due to failure to maintain:

Failure to maintain machines in good working order can and does lead to sever accidents. Most of the accidents resulting from machine failure electrical, mechanical, hydraulic etc.- can be traced to poor machine maintenance. A jammed bearing making a shaft break, a worn out key causing a double stroke in a power press or a faulty switch short circuiting the interlock system are common causes of accidents, if system of preventive maintenance is poor and one should take following care in this regard.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSProvide routine care to all components.Regular inspection and checking of all machines and its components.Timely identification and replacement of defective components.Periodic lubrication as per standards.Arrangements to bring any deviations, failure, or abnormal behaviour to the notice of persons who can initiate corrective action.

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Accidents due to incorrect maintenance: Examples.The machine is overhauled, but the guard is not replaced.An electric motor is replaced, but the earth connection is forgotten.Incorrect assembly, adjustments or settings.Poor or defective workmanship.

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The possible remedies for these lie in :-Training of the maintenance crew.Installing procedure for strict quality control in maintenance work. (Stages of inspection are introduced to make sure the work is going on as per specifications & standards.)Batter quality of supervision.

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Accidents during maintenance:

Maintenance and repair work have character different from routine production work. Firstly, the work is not repetitive in nature and the problems encountered are not the same always. Workman have to take inconvenient and dangerous postures due to the exigencies of the job. There is an element of RUSH in majority of jobs, which encourages short-cuts and indifference to safety requisites. Further, the equipment under maintenance itself is far less reliable than one in good working order and normally, the safety features are absent during maintenance. These conditions offer increased chances of accidents during maintenance/repair work and the typical examples are:

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Accidental descant of a ram in a power press during repairs.Accidental starting of machines or sudden movement of components.Sudden release of energy as in the case of rebounding of springs.Accidents while removing/replacing heavy components in difficult positions.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe solution to the problems lies in recognising the increased hazards in maintenance and taking additional safety measures and the following elements should be the part of any maintenance programme:-

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Advanced planning, job safety analysis and establishing safe work methods.Training of maintenance crew.Good quality of supervision.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSOnce these issues are studied, the broad requirements of safeguards surface, and considering the operation, cost of safeguarding and convenience, a decision can be taken regarding the protection to be chosen.Basically the approach should be to make the machine itself intrinsically safe without relying on the operator.When this is not practically possible, the machine should be made safe to the extent possible and any deficiency existing should be compensated by improving the reliability of the operator and his performance.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSPrinciples Of GuardingAll the mechanical action or motion of any type of machine are hazardous, but in varying degrees. These movements of machinery having parts like rotating members, reciprocating arms, moving belts, meshing gears, cutting teeth etc. requires the necessary protection which one or the other way turns into the some form of impact, shearing/cutting or bending action with the following type of motions or the situation:

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Rotary;Sliding or Reciprocating; orA combination of both the above;Transverse motions;In running Nip Points.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSHazardous actions & motions in machines

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSTypes Of GuardingDepending upon the principles of operation guards can be classified into the following four main types of guarding:Fixed GuardsInterlock GuardsAutomatic GuardsTrip Guards or Other safe-guards.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSFIXED GUARDS:

This has no moving parts and is a barrier between the dangerous part and the man which is fixed to the machine and remains permanently fixed by preventing access to the dangerous parts of the machine to man. A cycle chain cover or a grill in front of a fan are the examples of fixed guards. Other examples are fixed covers for gears, enclosures for fly wheels and common guards for belt derives. These Fixed Guards can be further sub classified as:

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEnclosing guards: Prevents access to danger points by enclosure.Distance guards: Does not completely enclose a hazard but reduces access by virtue of its physical dimensions and distance from the hazard.Adjustable guards: Fixed guards incorporating an adjustable element to allow for different operations or materials to be used in the same machine.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSSelf adjusting guards: A fixed or movable guard which adjusts itself to allow the passage of material and is actuated by the passage of the workplace or material at the start of the operation and returning to the safe position on completion.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSFalse Table: Can be used to overcome the problems presented by power operated feed tables, and which has the effect of filling the space between the workplaces on rotary or traversing feed tables, and thereby blanking off openings in guards while the machine is in operation.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe main advantage the fixed guard has over the other types of guards is that it is comparatively simpler in design and use, robust in construction and if it can be opened or removed it would be possible only with the aid of special tool and it is not possible for operator or any one to simply remove such guards.

Advantages of Fixed Guards

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSFixed guard is ideal choice when the parts to be guarded are not required to be approached often in the course of work but are not suitable where the moving parts are to be approached every now and then, for example, in case of a V-Belt derive where the belts have to be changed frequently for speed-changing, the chances are that the operator will keep the guard removed (Partly adjustable, folding or sliding arrangements can be incorporated in fixed guards for such arrangements provided it can be ensured (by means of interlocking or increased operator reliability) that the guard is in its position after every adjustment and the machine is stopped when the adjustment is carried out.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThey seldom need routine adjustments, and as a result causes less maintenance problem and costs less.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS.A fixed guard provides the highest degree of protection against danger/hazards and should always be the first choice of guard where ever possible.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSINTERLOCK GUARDS:

When a fixed enclosure guard is not practicable, an interlocking enclosure or barrier should be considered as a first alternative. When the fixed guard can not be used in situation where the moving parts have to be approached frequently, as in case of lift door in which people have to go in and out, or power press in which the operator has to put in his hand to feed the job and take out an interlock guard may be the ultimate choice with a device or system which links the function of the operator and the machine in such a way that (a) the parts are not accessible when the danger is present (b) when the parts are accessible, the danger is not present and that can be achieved by mechanical, electrical, hydraulic or electronic systems.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSAn interlocking enclosure guard is not fixed and may be opened or removed as the operator requires. However due to an electrical or mechanical interlocking connection with the operating mechanism, the operation of the machine is prevented until the guard is returned to an operating position and the operator can no longer reach the point of danger. An interlocking guard should do three things:

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSShut off or disengage the power to prevent the starting of the machine when the guard is open.Guard the danger point before the machine can be operated.Keep the guard closed until the dangerous part is at rest, or stop the machine when the guard is open.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSInterlock systems are effective, only if they are correctly designed, installed and adjusted. They also need to be periodically inspected, checked, adjusted and maintained in good shape & condition. A loose nut in the interlock for the stroke mechanism, a defective contact in a switch or the wrong adjustment of a cam can easily defeat the purpose of the interlock guard.

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Limitation of Interlocking

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSSome examples of interlock systems are:Operation of the passenger lift is electrically so controlled that the lift does not move when the doors are open and that the doors cannot be opened when the lift is moving.In power press a guard provided in front of the dangerous zone is so linked with the stroke mechanism that with the guard off, the stroke can not be released by the pedal (or hand).

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSCam activated switches which puts off the supply in case doors leading to dangerous parts are opened.Two hand control devices in which both the hands of the operator are required to be busy during operation-For example he has to press two buttons simultaneously with both hands to activate stroke in hydraulic presses.Trapped key systems in which dangerous parts have to be securely locked in to release the key required to switch on the machine. Without proper locking in, the key for machine operation remains trapped in its key hole.

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Some other forms of interlock systems are:Control guards:

The action of closing the guard initiates the operation of the machinery.The machine can not start until the guard is closed, andThe guard remains locked closed during any dangerous motion.

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Enclosure guards:

Prevent access to danger points by enclosure.Distance guards:

Does not completely enclose a hazard but by virtue of its dimensions and its distance from the hazard reduces access.

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In addition, rotation or motion sensing devices which are interlocked with machine derive mechanisms or power supplies may be used.It should be appreciated that the overall aim of any interlocking guard system should be to minimize the possibility of the whole system Falling into danger

Specific application of Interlocking

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSAUTOMATIC GUARDS:

When neither an enclosure guard nor an interlocking guard is practicable, an automatic guard may be used. Where in the interlock guard an action by the operator is necessary to activate the protection mechanism, the automatic guard is one which functions independently of the operator by repeating its cycle as long as the machine is in motion. As these guards are moved into position automatically being operated by the machine itself through a system of linkages connected to the operating system and remove any part like hands, arms or body of a person from the danger zone as the ram, plunger or other tool closes on the piece upon which work is being done. The essential requirement of such guards is that they do not create a hazard in themselves in their operation. These guards are comparatively costlier & demands very good maintenance standards, periodic adjustments and frequent checking. .

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS Common type of automatic guards are sweep and push-away devices which are moving barriers crossing the danger zone when the machine is activated, and pull-away devices consisting of and arm attachments which pulls the operator away from the danger zone. These devices should be designed to prevent the operator from reaching behind or across the protective device into the danger zone before the machine has completed its closing cycle.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe guard must be securely fixed to the machine so that it cannot be adjusted or detached without the aid of tools; and should be actuated by the dangerous part of the machine itself.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe main advantage of such guards is that they must work in time with the machine movement, thus they are generally unsuitable for the fast acting machines.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe principle of working of such guards can be understood by following three examples:In the hand pull-out device in a power press the operators hand has a strap which is connected through a series of pulleys to the ram itself. The strap itself is light and with the ram up the hands are quite free. The operator can without any trouble or inconvenience carry out normal work of removing the finished job, feeding the next one and taking out the hand before activating the stroke. But, in process, if he forgets or fails to take out the hand (as it happens many times) the motion of the ram coming down simultaneously pulls his hand out.

Principles of Automatic Guards

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSInstallation of a sweep guards in front the die in power press in such a way that when the ram comes down the sweep traverse, from left to right, (or right to left or backwards or forward depending on the need) and removes the hand of the operator, if it happens to remain in the danger zone.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSLight from electrical bulbs installed in front of a sheering machine on one side falls on photo-electric cells installed on the other side. This light beam acts as a guard and if it is interrupted by any thing, including the hands of the operator the machine (or the process) is brought to a stop.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSTRIP GUARDS:

These devices are not guards as such; they are devices which causes working machinery to stop/trip or assume a safe position or condition when a person approaches a danger point or into the area beyond a safe limit, they are also required to maintain the machinery in such a safe condition while a person remains in the danger area, and such devices fall into two broad categories:Mechanical trip devices, andElectrical/ electronic devices.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS There are other methods also to make machine operation safe, like:Arrangements to reduce/eliminate human components of work. A typical example in substituting automatic feed in place of manual feed. Also arrangements to have automatic ejection in power presses eliminates the need of operator having to put his hand in the dangerous areas.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS.Use of special tools: Nose-pliers, screw drivers. Tongs specially designed pliers etc. can be used to hold the job, feed the job etc. such that their use eliminates the need of hands reaching dangerous area. How ever it has to be ensured that the tools used is convenient for operation, and also that the operator does make use of it.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSWarning devices, Indicator lights and signals can be used to warn the operator of eminent dangers. e.g. A red light burns when the guard is in open position.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe common way in which the guards are misused by the workmen are:Guards removed by the operator or defeated in many manner for apparent convenience or faster rate of production under incentive scheme.Guards removed by maintenance workers or setter or not put back.Guards not adjusted correctly.

Never to Forget

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe problem of misuse of guards is not confined to workmen alone. One can easily come across case of wrong selection, wrong design, wrong installation and wrong use of guards in industries.

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*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSNearby every such machine, a notice indicating safety aspects be provided, safe working speed should be mentioned on it. As the Sec.30 of Factories Act. covers safety precautions in the use of grinding wheels. It specifies a notice indicating maximum safe working, peripheral speed of grinding stones, the speed of shaft or spindle etc. The section also says that the safe peripheral speed of any revolving cages, vessel, basket, fly wheel, pulley, disc or similar appliances driven by power is not exceeded.

Rotating Machines

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSPrinciples of Safety Integration, like any applied science, is based upon fundamental principles and rules of practice. As such it involves the identification, evaluation, and control of hazards in man-machine systems (products, machines, equipment, or facilities) that contain a potential to cause injury to people or damage to property. Briefly stated, the basic rules of hazard control involve system design, the use of physical safeguards, and user training. Further, it must be thoroughly understood that no safety device equals the elimination of a hazard on the drawing board, and no safety procedure equals the use of an effective safety device.This approach has been advocated by the safety literature and successfully practiced by safety professionals for decades.

Principles of Safety Integration

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSEvery activity must be carried out in accordance with a developed Safe Working Practice.This shall be validated by means of a Risk Assessment.The control measures identified in the risk assessment shall form the basis for the written Safe Working Practice.The Safe Working Practice shall follow a logical sequence of progression.Consider what must be done before the task starts?How the task is done?What training is needed?What competence is required or certification?The action to be taken when the task is complete.The Safe Working Practice shall be developed by the persons conducting the task and led by the Responsible Manager or person concerned.

Safe Work Practice

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSThe Responsible Manager should delegate responsibility.Delegation must be confirmed in writing, and the manager must be assured that the delegate is competent to lead the development process, via internal training.The Responsible Manager shall review all Safe Working Practices, before adoption in the workplace.All Safe Working Practices shall be dated and assigned a version number.In orders to track changes and ensure employees are using the latest version.Any changes considered necessary shall be discussed with the persons whom have developed the Safe Working Practice.Agreement shall be warranted, from all parties, before the practice is adopted.If in doubt, ask!

How do we comply a Safe Work Practice ?

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS1. Guards are free of sharp edges, protrusion into walkways, etc., that cause the guard to be a hazard. 2. Where drums or barrels are revolving (tumble blending) to blend materials, an enclosure with the entrance interlocked with the drive is present and functions properly. 3. Fans which are less than 7 feet above the floor are guarded with openings 1/2' or less. 4. Machines designed for a fixed location are securely anchored to prevent them from walking or moving. 5. Table saws have guards which enclose the blade above the table and when cutting, the exposed blade above the material being cut. 6. Disk sanding machines have a guard enclosing the revolving disk.

Check List for Machine Guards

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS7. Belt sanding machines have guards at each nip point where the sanding belt runs into a pulley. 8. Grinding wheels have: a. Work rests adjusted to within 1/8" of the wheel. b. A guard over the spindle end, nut and flange projections. c. For most grinders, the acceptable unguarded opening is 65 deg. above the horizontal and 90 deg. total maximum exposure.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS9. Friction brakes are capable of quickly stopping the operation of the press and holding the slide in constant position 10. Foot operated presses: a. Have pedals protected to prevent accidental activation of the machine by falling objects or accidentally stepping on the pedals. b. Have pads of the pedal with nonslip contact areas. 11. Hand lever operated power presses have a spring latch on the operating lever.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS12. The operating levers on the hand-tripped presses having more than one operation are interlocked to prevent the tripping of the press except by the concurrent use of all levers. 13. On machines using part revolution clutches in addition to the above: A red color stop control is used to open the clutch, apply the brake and stop the machine. 14. The main power disconnect switch on each machine is capable of being locked only in the main of position.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS15. The motor start button is protected by a guard, cover, etc., to prevent accidental operation. 16. Mechanical power presses controls have driven motor starters that automatically disconnect from the power source when there is a power failure. 17. Electrical clutch/brake control electrical circuits have features which will prevent an accidental ground in the control circuit causing false operation of the press.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS18. All point of operation guards. a. Prevent entry of hands or fingers into the point of operation by reaching through, over, under, or around the guard. b. Comply with the following table which shows the distances those guards is positioned with the indicated opening in the guard. Distance of Opening from Maximum Width of Opening (inches) Point of Operation Hazard (inches)

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS19. Where power presses are not equipped with point of operation guards, a point of a. A device to prevent and/or stop the press if the operator's hands are inadvertently placed in the point of operation (e.g., light beam which when broken stops the press or restraints). b. A device such as cables are connected to the employee's wrists that prevent the employee from placing his hands in the point of operation. c. Two hand controls exist. 20.a. The distance of each control from the point of operation is appropriate. b. The hand controls must be mounted so that an operator cannot easily move them.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS21. Dies to control or eliminate hazards are stamped with the tonnage and stroke requirements. 22. Die handling equipment with attach points is provided on all dies requiring mechanical handling. 23. Inspection or presses are done weekly and records are available covering the inspection of: a. The condition of the clutch/brake mechanism. b. Anti-repeat and single stroke mechanisms. c. All guards are in place. d. All other safety features of the press are in operating condition and properly adjusted. 24. Employees are trained in inspecting and maintaining power presses.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDS25. For mechanical power-transmission apparatus: a. Flywheels set 7 feet or less above the floor or platform are guarded either with an enclosure or guardrail. The guard must have sufficient strength to control the flywheel in the event the shaft fails. b. All crank and connecting rods when exposed to contact are guarded.26. A checklist covering the inspection of power transmission equipment is completed every 60 days and kept in good working condition at all times.

Contd.

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSSection 2(Ca); Model Rule 2A: defines competent person as such a person or an institution who has qualifications, experience and facilities to carry out examinations and inspections required by the Factories Act and is recognized by The Chief Inspector of Factories. The competent person should not be above 62 years of age. Types of qualification, experience and facilities at command may vary with types of competency required namely: pressure plants, lifting machines, suitability & stay ability certificate and ventilation system etc.

Competent Person

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSInspection, Testing & due Certification should be carried out and ensured by the user in physical presence of the competent person of all these equipment's (like: lifting tools & tackles, hoists, lifts, cranes), machines, pressure vessels / plants, boilers, buildings & structures etc. as per the schedule and directives of the state rules prescribed there in the Factories Act vide various sections (like: Section 28 to 40, 40A) and The Indian Boiler Act with due course of interval of time by maintaining its record along with the compliance of inspection notes / reports for the purpose.

Inspection, Test and Certification

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSBeside state rules for achieving better performance in the field of industrial safety any management should encourage its personnel to follow safety rules & procedures.The rules framed should be simple and understandable and should avoid conflicts of opinion.They should meet the objectives of the company and they may be changed as and when situations demand.The management should see that the rules are framed only when they are essential.The number of rules should not be too much to create confusions and frustrations among people.

Safety Rules


Power Press Regulations

*IIMSHE*MIS-003 PGDM 1st semesterMACHINES & MACHINE GUARDSENSURE SAFETY

IIMSHE

Mis003

Education

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