Field balancing

Rotor balancing under operating conditions

Unbalance is the most common cause of damage in rotating machines. It can be found in fans, ventilators, belt pulleys and couplings. The enormous centrifugal forces resulting from the uneven mass distribution generates high vibrations during rotation, which affects the entire machine construction. This can cause bearings, seals and couplings to wear prematurely or even fail.
An unbalance is easy to detect in the vibration spectrum because it vibrates in sync with the shaft rotational speed. Its energy is concentrated at the first harmonic spectral line. This can be remedied by balancing the installed rotor with a portable balancer, a process known as field balancing.

Balancers from PRUFTECHNIK are optimized for detecting and eliminating unbalance in just a few steps. Besides standard applications, such as industrial fans of all sizes and shapes, the balancing devices are also ideal for special requirements, such as field balancing of rotor blades on wind turbines.

Field balancing

Causes of unbalance in fans, ventilators, blowers

Manufacturing defects

  • Difference in fit between the balancing and ventilator shafts
  • Centrifugal force deformation
  • Blade sag
  • Blade cracks
  • Improper paintwork or coating
  • Strain from rotor disk weld.


Installation errors

  • Faulty axial blade mounting
  • Loose or tilted hub-to-shaft fit
  • Bent shaft seat
  • Imbalance on belt pulleys.

Unbalance from repairs

  • Missing balancing masses
  • Unbalance on coupling
  • Improper paintwork or coating
  • Detached coating.


Unbalance from operation

  • Fouling on rotor disk
  • Local corrosion
  • Droplet erosion
  • Heat deformation
  • Wear from solids
  • Stray imbalances
  • Solid and fluid inclusions in hub shell.



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Field balancing

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