Dynamic Balancing

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 When man invented the wheel, he very quickly learned that if it wasn't completely round and if it didn't rotate evenly about it's central axis, then he had a problem.

The wheel would vibrate, causing damage to itself and its support mechanism and in severe cases be unusable. Research showed that a wheel had to be in a state of balance so that vibration was eliminated.

Modern man still suffers from the same problem -- only now the problem is amplified. As machines get bigger and go faster, the effect of the unbalance is much more severe.

A level of unbalance that is acceptable at a low speed is completely unacceptable at a higher speed. The unbalance condition increases by the square of the speed. Prolonged exposure to the vibration results in damage and increased downtime of the machine.

Identifying and correcting the mass distribution and thus minimizing the force and resultant vibration is the technique known as dynamic balancing.
 

 
Everything that rotates needs to be in a state of balance to ensure smooth running when in operation.

Modern technology allows for accurate balancing to be performed both in the field and in the workshop.

Priest Electric offers both services.

 

 

Manufacturing Causes: Many causes are listed contributing to an unbalance condition including material problems such as density, porosity, voids and blowholes. Fabrication problems such as rotational stresses, aerodynamics and temperature changes. Many of these occur during manufacture, others during the operational life of the machine.

Assembly Causes:  Principle among these is a stack up of tolerances. When a well-balanced shaft and a well balanced rotor are united, the necessary tolerances can permit radial displacement, which will produce an out of balance condition. The addition of key and keyways adds to the problem.

Installed machine causes: When a rotor has been in service for some time, various factors can contribute to the balance condition. These include corrosion, wear, distortion, and deposit build up. Deposits can also break off unevenly, which can lead to severe unbalance. Routine inspections and cleaning can minimize the effect, but eventually the machines will have to be removed from service for balancing.

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Benefits of Balancing machinery

  • Minimize vibration - Unbalance is still the major source of machine vibration.

  • Minimize noise - Airborne noise is often directly attributable to mechanical vibration.

  • Minimize structural stress - The forces produced by unbalance have to be absorbed by the surrounding structure

  • Minimize operator fatigue and annoyance - Exposure to high levels of vibration and noise affects operator efficiency.

  • Increase machine life - The time between outages can be extended if the machine is running smoothly.

  • Increase bearing life - Bearings bear the brunt of the unbalance forces.

  • Increase product quality - Minimum vibration, especially on machine tools, produces better parts.

  • Increase personnel safety - Dangers associated with machine failure are minimized.

  • Increase productivity - Machines running smoothly have more "uptime" availability.

  • Lower operating costs - Extra machines are not required "just in case" of breakdowns. Spare capacity is kept to a minimum. Energy consumption is reduced.

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