Services

Field balancing

Rotors balancing procedure

Balancing is performed only for technically sound mechanisms, properly fixed in their proper places. Otherwise, before balancing the mechanism must be repaired, installed on serviceable bearings and fixed. The rotor should be cleaned of impurities interfering the balancing.

The Customer provides safe working conditions for balancing, switching the mechanism on and off, provides personnel to carry out the necessary plumbing and welding works to access the balancing rotor and to install testing and corrective weights. The work requires access to the 220 V 50 Hz electrical network to power the device.

The rotors are balanced in one or two correction planes. The number of balancing planes is determined taking into account the balancing machine rotor design features. One plane balancing (“static”) is usually performed for narrow disc rotors. Typical examples of such like rotors are: narrow grinding wheels, belt pulleys, disk flywheels, etc.

Two planes balancing (“dynamic”) is performed for long (shaft) two-bearing rotors. Typical examples of such like rotors are electric motors and generators rotors, compressors and pumps rotors, fans rotor wheels, wide grinding wheels, spindles, milling machines shafts with bars, etc.

The rotor speed should not fall within the machine resonance range. A difference (by more than 10-20%) of the measurement results in amplitude and/or phase from start to start testifies of this. If resonance is detected, it is necessary to change the rotor speed, and if it is not possible, to change the installation conditions on the foundation (for example, its temporal installation on elastic supports).

The vibration sensor can be installed at the measuring point with the help of: - threaded rod (rigid mounting); - magnetic suction cup. The phase angle sensor can be mounted on the machine body with a special tool and should be normally oriented to the rotor cylindrical or end surface. Rotor surface is to have a mark applied with chalk, adhesive tape, etc., to indicate the phase angle.

Balance criteria according to the ISO 10816-1-97 (ISO 2372). Vibration levels limit values established for four classes of machines are given in Table P.1.

 

                              *)

Machine class 

Admissible vibration levels, mm/s RMS
Good Admissible Still admissible Inadmissible
1 < 0.7 0.7-1.8           1.8-4.5     > 4.5
2 <1.1 1.1-2.8           2.8-7.1 >7.1
3 <1.8 1.8-4.5    4.5-11 >11
4 <2.8 2.8-7.1 7.1-18 >18

*) Note:

- Class 1 corresponds to small machines installed on rigid foundations (analogue - electric motors with a capacity of up to 15 kW);

- class 2 corresponds to medium-sized machines installed without separate foundations (analogue - electric motors with a capacity of 15–75 kW), as well as driving mechanisms on separate foundations with a capacity of up to 300 kW;

- Class 3 corresponds to large machines installed on rigid foundations (analogue - electrical equipment with a capacity of over 300 kW);

- Class 4 corresponds to large machines installed on lightweight foundations (analogue - electrical equipment with a capacity of over 300 kW).

 

PS

- Equipment repair is not available.

- This type of work is not covered by the warranty.