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Maintenance

 

Increased attention to maintenance of tools and equipment will reduce worksite noise levels. Maintaining your plant and equipment in good order not only increases its life, but makes it safer to use and quieter. In many cases, a noise hazard will be created or made worse by a lack of maintenance. Parts may become loose, creating more noise because of improper operation or scraping against other parts. Grinding noises may also occur as the result of inadequate lubrication. It is especially important to provide proper maintenance of noise control devices which are added or built into machinery. Loose and worn parts should be fixed as soon as possible.

Always check and see if there are any problems starting to appear with a machine or equipment. Check for signs of wear or if the machine’s performance is down. Some problems will appear as looseness or increased vibration. Listen for new noises, especially tonal ("whining") sounds, repeated impacts, or high frequency ("screech") sounds. Also, slipping belts will cause a screech at start-up, while a damaged bearing may appear as a "clunk" during run-down.

Ideally, the worksite should have a system in place for checking and servicing the various machines and power tools. Below are examples of ways maintenance and servicing can make equipment safer and quiet.

 

Why machines get noisier with use:

  1. Worn or chipped gear teeth – will not mesh properly. The shiny wear marks are often visible on the teeth.
  2. Worn bearings - bearing wear creates vibration and noise, as flat spots or cracks appear in the balls.
  3. Slackness between worn or loose parts – causes rattling noises, squealing from slack drive belts, "piston slap" in motors, air leaks, etc.
  4. Poor lubrication – causes squeaking noises due to friction or impact noise in dry and worn gears or bearings.
  5. Imbalance in rotating parts – imbalances with fan impellers or motor shaft will show up as excess vibration.
  6. Obstruction in airways - a build-up of dirt or a bent/damaged piece of metal in an airway or near a moving part, e.g., a bent fan guard, can cause whistling or other "air" type noises.
  7. Blunt blades or cutting faces - blunt or chipped saw teeth, drill bits, router bits etc, usually make the job noisier as well as slower.
  8. Damaged silencers - silencers for air-driven machines or mufflers for engines may become clogged with dirt, rusted out or damaged, so losing their ability to absorb noise.
  9. Removal of a noise-reducing attachment - mufflers, silencers, covers, guards, vibration isolators etc. which reduce noise should never be removed except during maintenance, and then must be replaced
Maintenance
Problem:
A common type of reciprocating air compressor produced 94 dB (A) at 1m
Solutions:
• Regrinding the valves to improve the seal resulted in a significant noise reduction of approximately 7 dB (A).
• Introducing an oil additive gave an extra 1 dB(A) reduction
Benefits and Costs:
The overall noise reduction due to the re-seating of the valves and the introduction of the oil additive is therefore estimated to be approximately 8 dB (A). This is significant, in that the reduction was achieved at minimal cost, using methods which could be adopted by any skilled maintenance trades person.
Acoustically Treated Noise Level:
86 dB(A) at 1m

Reference: WorkSafe Western Australia, “Successful noise management in manufacturing," 2014.

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