| Rough Mill > Noise
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 Simple and practical methods
discussed below can reduce noise levels considerably. These methods focus on three basic approaches to controlling noise:
noise source controls, noise path controls, and hearing protection. Noise source controls, which typically consist
of engineering controls, provide the most effective means of protection, since they actually reduce the
amount of noise generated in the workplace. For this reason, it is best to exhaust source control
options first, before moving on to path controls and, finally, to hearing
protection devices.
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Source control begins with a thorough analysis of each piece of noise-generating equipment.
Attempt to identify all noise sources within a given piece of equipment, as well as the ways in
which the sound is transmitted (and often amplified via resonance or vibration)
to the surrounding room. Then every effort should be made to both quiet the sources and dampen the resonant
pathways
of transmission. Noise sources generally include motors, gears, belts and pulleys, points of
operation where blades touch wood, and any other moving parts. Resonant transmitters generally
include the frames, footings, and housings of the equipment.
Possible Solutions:
- Maintain motors and all moving parts in top operating condition.
Maintenance involves lubricating and cleaning; replacing worn parts;
maintaining proper belt tensions and bolt torques; and properly balancing
pulleys, blades, and other rotating parts.
- Reduce the speed of operation of the equipment to the slowest level
consistent with product quantity and quality goals.
- Move power equipment operations out of wooden or steel-frame buildings and into
stone, cement, or brick structures, if at all possible.
- Ensure that equipment frames are as rigid as possible, that equipment is firmly seated
on a solid floor (preferably cement slab), and that no piece of equipment is in contact with
any other piece or with walls.
- Isolate noisy equipment with rubber footings, springs, or other forms
of damping suspension so as to reduce the radiation and amplification of noise via vibrations.
- Apply vibration-damping materials to all resonating surfaces, and
construct (where possible) sound absorbent hoods around points of
operation.
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Effective path controls involve isolating, blocking, diverting, absorbing, or otherwise
reducing noise intensity before it reaches the employees' ears.
Possible Solutions:
- Segregate operations so as to limit, as far as possible, the number of employees
exposed to excessive equipment noise.
- Enclose equipment within barriers designed to absorb noise and/or
reflect it in harmless directions, such as toward ceilings covered with
sound absorbent material.
- Move or locate noise-producing equipment away from employees,
since noise intensity decreases significantly as you move away from the
source of the noise. Depending on the types of surfaces in your workplace, you can reduce the level of noise
that your workers are exposed to by up to 6 dBA by doubling the distance between the
source of the noise and your workers. The presence of reflective surfaces (such
as flat metal surfaces) in the workplace will reduce the level of noise
reduction achieved by this method.
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Hearing protection devices isolate the human ear from harmful noises.
They should be worn by employees as the final line of defense against noise hazards. Hearing
protection devices can be effective and, compared to source and path control efforts, relatively
inexpensive. Their use, however, demands a considerable level of ongoing effort and
commitment.
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Given the nature of woodworking operations, production floor employees will almost
certainly require hearing protection devices.
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Fig 1 - Earmuffs are a way
to protect hearing. |
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