Noise and vibration
Noise and vibration often occur together in a foundry environment.
Noise
In the foundry industry people are subjected to a variety of noise sources. High noise levels from sources, such as vibrator systems to compact moulding sands in moulds, arc/air gouging and fettling activities and particularly those of short duration, such as impulse or impact noise, are present in many foundries and are capable of causing damage to hearing.
Foundries form part of the metal fabrication industry. This industry is responsible for a large proportion of worker's compensation payouts for noise induced hearing loss of its workers.
In foundries noise levels can be expected to range generally between about 80 and 110dB(A). Most common noise sources are from mould vibrators, shake outs, rumblers and shot blasting, arc gouging and fettling and dressing of castings, using angle grinders and hammering and banging on castings.
Operator noise exposure levels from the above sources, of between 96 - 102dB(A), as average over the shift duration, are not uncommon in this industry. Noise sources may also be found from induction furnaces. The frequent use of compressed air systems to clean moulds or work benches, cause high noise levels consisting of predominantly high pitched components.
A variety of woodworking machines in the making of mould patterns also add to the noise exposure. All of these noise sources combine to create high ambient noise levels in foundries and the use of personal hearing protectors is required in most situations.
Generally where high levels of noise are present throughout the work shifts, workers do tend to wear personal hearing protectors most of the time. However, with short duration noises, for example, a few belts with a hammer on a metal casting or using compressed air to clean a mould or work bench, the use of hearing protectors is often ignored or simply not even thought of. These relatively short duration exposures however, happen many times per shift and add to the overall exposure.
Typical noise sources
Some typical noise sources in the foundry industry at operator ear level include:
| Mould vibrators | 85 - 114dB(A) |
| Inverter | 83 - 116dB(A) |
| Arc/air gouging | 82 - 107dB(A) |
| 9 inch angle grinder | 97 - 110dB(A) |
| Shot blasting | 86 -101dB(A) |
| Shake out | 84 -95dB(A) |
Noise control measures
Risk management must be applied through a hierarchy of control measures, ie. elimination, substitution, engineering and/or administrative controls, and as a last resort, (or as an interim measure or in conjunction with other control options), reliance on protective equipment.
It is important that foundry operators have a noise control policy and hearing conservation program in the workplace to manage noise levels in the foundry environment.
Examples of engineering noise control measures include:
- installing modifications such as rotary vibrators
- installing vibration isolating mountings
- locating noisy equipment such as automatic moulding machines and vibrators in separate enclosures
- providing a sound proof enclosure for operators
- installing improved mould design that can eliminate or drastically reduce the amount of excess metal to be removed after casting. This in turn removes or reduces the need for fettling
- using low noise, or noise reduced, grinding discs. This can reduce the noise levels by up to 5dB(A)
- 'buffer' mould boxes where automatic lines are used in order to reduce striking noise from boxes on conveyers
- fitting suitable silencers to compressed airlines
- lining mobile enclosures internally with 75 mm sound absorbent material such as mineral wool where noisy work has to be carried out. This could reduce operators exposures by about 5 to 20dB(A) depending on construction etc. The additional effect is also to reduce the exposures of nearby workers.
Examples of administrative noise control measures include:
- introducing a 'buy quiet' policy
- training workers, for example fettlers, about noise issues
- sign-posting noisy areas
- maintaining equipment
- reducing the amount of time operators spend in noisy areas through job rotation to reduce and control individual exposures from noisy work, for example, arc/air gouging and fettling activities
Where noise control cannot be achieved through these measures an employer must provide suitable personal hearing protectors as well as proper instruction in their use so that exposed workers can perform their work in a manner which is safe and without risks to their health and safety.
For more information on how to deal with noise issues, refer to:
- Noise section of the Foundry Industry Code of Practice 2004
- Noise Advisory Standard 2004 (now known as a Code of Practice)
More about noise.
Vibration
Foundry workers may be exposed to whole-body vibration and hand-arm vibration.
The health effects of vibration can include blood pressure and heart problems, nervous disorders, and blanching and numbness in the fingers.
Control measures for vibration include:
- purchasing vibration reduced equipment
- using tools with vibration dampers
- avoiding prolonged use of vibrating equipment
- providing protective gloves
For more information on how to deal with vibration issues, refer to vibration section of the Foundry Industry Code of Practice 2004.
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