MACHINE SAFETY
Basics of Machine Safeguarding
When the operation of a machine, or accidental contact with it, can injure the operator or others in the
vicinity, the hazards must be either controlled or eliminated. Dangerous moving parts in three basic
areas require safeguarding:
1. The point of operation: that point where work is performed on the material, such as cutting,
shaping, boring, or forming of stock.
2. Power transmission apparatus: all components of the system which transmit energy to the
part of the machine performing the work, such as flywheels, pulleys, belts, and gears.
3. Other moving parts: all parts of the machine which move while the machine is working.
These can include reciprocating, rotating, and transverse moving parts, as well as feed
mechanisms and auxiliary parts of the machine.
Hazardous Motions
Rotating motion: even smooth, slowly rotating shafts can grip clothing, or force an arm or hand into a
dangerous position. Rotating mechanisms include cams, flywheels, shaft ends, and meshing gears.
The danger increases when projections such as set screws, bolts, abrasions, and projecting keys are
exposed on rotating parts.
In-running nip point hazards are caused by the rotating parts on machinery. There are three main
types of in-running nips:
1. Parts rotate in opposite directions. These parts may be in contact or in close proximity. In the
latter case, the stock fed between the rolls produces the nip points.
2. Nip points created between rotating and tangentially moving parts. An examples would be the
point of contact between a power transmission belt and its pulley.
3. Nip points created between rotating and fixed parts which create a shearing, crushing, or
abrading action. An examples would be the edge of an abrasive wheel and an incorrectly
adjusted work rest.
Reciprocating motions may be hazardous because a worker may be struck by or caught between a
moving and a stationary part.
Transverse motion (movement in a straight, continuous line) creates a hazard because a worker may
be struck or caught in a pinch or shear point by the moving part.
Requirements for Safeguards
Safeguards must meet these minimum general requirements:
1. Prevent contact: The safeguard must prevent hands, arms, and any other part of a worker's
body from making contact with dangerous moving parts. A good safeguarding system
eliminates the possibility of workers placing parts of their bodies near hazardous moving parts.
2. Secure: Workers should not be able to easily remove or tamper with the safeguard. Guards
and safety devices should be made of durable material that will withstand the conditions of
normal use. They must be firmly secured to the machine.
3. Protect from falling objects: The safeguard should ensure that no objects can fall into
moving parts. A small tool dropped into a cycling machine could easily become a projectile
that could strike and injure someone.
4. Create no new hazards: A safeguard should not create a shear point, jagged edge, or
unfinished surface which can cause a laceration. For example, the edges of guards should be
rolled or bolted to eliminate sharp edges.
5. Create no interference: Any safeguard which impedes a worker from performing the job
quickly and comfortably might soon be overridden or disregarded. Proper safeguarding can
actually enhance efficiency since it can relieve the worker's apprehensions about injury.
6. Allow safe lubrication: If possible, workers should be able to lubricate the machine without
removing the safeguards. Locating oil reservoirs outside the guard, with a line leading to the
lubrication point, will reduce the need for a worker to enter the hazardous area.
Training
Even the most elaborate safeguarding system cannot offer effective protection unless the worker
knows how to use it and why. Thorough operator training should involve instruction or hands-on
training in the following:
1. A description and identification of the hazards associated with particular machines;
2. The safeguards, how they provide protection, and the hazards they guard against;
3. How to use the safeguards and why;
4. How and under what circumstances safeguards can be removed, and by whom (in most cases,
repair or maintenance personnel only); and
5. What to do if a safeguard is damaged, missing, or unable to provide adequate protection.
This kind of safety training is necessary for new operators and maintenance or setup personnel, when
any new or altered safeguards are put in service, or when workers are assigned to a new machine or
operation.
When the operation of a machine, or accidental contact with it, can injure the operator or others in the
vicinity, the hazards must be either controlled or eliminated. Dangerous moving parts in three basic
areas require safeguarding:
1. The point of operation: that point where work is performed on the material, such as cutting,
shaping, boring, or forming of stock.
2. Power transmission apparatus: all components of the system which transmit energy to the
part of the machine performing the work, such as flywheels, pulleys, belts, and gears.
3. Other moving parts: all parts of the machine which move while the machine is working.
These can include reciprocating, rotating, and transverse moving parts, as well as feed
mechanisms and auxiliary parts of the machine.
Hazardous Motions
Rotating motion: even smooth, slowly rotating shafts can grip clothing, or force an arm or hand into a
dangerous position. Rotating mechanisms include cams, flywheels, shaft ends, and meshing gears.
The danger increases when projections such as set screws, bolts, abrasions, and projecting keys are
exposed on rotating parts.
In-running nip point hazards are caused by the rotating parts on machinery. There are three main
types of in-running nips:
1. Parts rotate in opposite directions. These parts may be in contact or in close proximity. In the
latter case, the stock fed between the rolls produces the nip points.
2. Nip points created between rotating and tangentially moving parts. An examples would be the
point of contact between a power transmission belt and its pulley.
3. Nip points created between rotating and fixed parts which create a shearing, crushing, or
abrading action. An examples would be the edge of an abrasive wheel and an incorrectly
adjusted work rest.
Reciprocating motions may be hazardous because a worker may be struck by or caught between a
moving and a stationary part.
Transverse motion (movement in a straight, continuous line) creates a hazard because a worker may
be struck or caught in a pinch or shear point by the moving part.
Requirements for Safeguards
Safeguards must meet these minimum general requirements:
1. Prevent contact: The safeguard must prevent hands, arms, and any other part of a worker's
body from making contact with dangerous moving parts. A good safeguarding system
eliminates the possibility of workers placing parts of their bodies near hazardous moving parts.
2. Secure: Workers should not be able to easily remove or tamper with the safeguard. Guards
and safety devices should be made of durable material that will withstand the conditions of
normal use. They must be firmly secured to the machine.
3. Protect from falling objects: The safeguard should ensure that no objects can fall into
moving parts. A small tool dropped into a cycling machine could easily become a projectile
that could strike and injure someone.
4. Create no new hazards: A safeguard should not create a shear point, jagged edge, or
unfinished surface which can cause a laceration. For example, the edges of guards should be
rolled or bolted to eliminate sharp edges.
5. Create no interference: Any safeguard which impedes a worker from performing the job
quickly and comfortably might soon be overridden or disregarded. Proper safeguarding can
actually enhance efficiency since it can relieve the worker's apprehensions about injury.
6. Allow safe lubrication: If possible, workers should be able to lubricate the machine without
removing the safeguards. Locating oil reservoirs outside the guard, with a line leading to the
lubrication point, will reduce the need for a worker to enter the hazardous area.
Training
Even the most elaborate safeguarding system cannot offer effective protection unless the worker
knows how to use it and why. Thorough operator training should involve instruction or hands-on
training in the following:
1. A description and identification of the hazards associated with particular machines;
2. The safeguards, how they provide protection, and the hazards they guard against;
3. How to use the safeguards and why;
4. How and under what circumstances safeguards can be removed, and by whom (in most cases,
repair or maintenance personnel only); and
5. What to do if a safeguard is damaged, missing, or unable to provide adequate protection.
This kind of safety training is necessary for new operators and maintenance or setup personnel, when
any new or altered safeguards are put in service, or when workers are assigned to a new machine or
operation.
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| This page was last updated: March 23, 2010 |
