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  • Field Balancing

    Balancing rotors is an important condition for a safe and longterm operation of machines. In machines that were not balanced, high mechanical vibrations can occur and lead to wear and fatigue. The resulting damage caused e.g. on bearing, shaft run or foundation ultimately lead to the shutdown of the machine and cause production losses.

    The machine that is to be balanced consists of components which are generally pre-balanced during production. However, new imbalances can be generated by the assembly of several components (rotor, gear, coupling). Changes in operation such as pollution and wear or changes due to repair measures like exchanging the bearing also lead to imbalances. In order to reduce these unwanted vibrations the machine is re-balanced in operational state. Therefore we speak of field balancing.

    Field balancing has the advantage that the machine is balanced as a whole. The superposition of imbalances of all individual components is determined and can be reduced. Furthermore, field balancing saves time and money, since the machine must not be disassembled with effort and balanced externally.

    During field balancing the rotor has to be accessible, in order to mount test and balance masses, adequate transducer locations for the accelerometer have to exist and there must be a possibility to determine the speed of the rotor.

    There is a wide range of applications of field balancing. Form large slow rotating roller mills to dynamic balancing of propellers of small aircrafts to tool spindles with speeds of several 10,000 U/min.

    • Fig. 1: Field balancing of roller mill
    • Fig. 2: Field balancing of small aircrafts

    In practice field balancing is performed with vibration analyzers. The connected accelerometers determine the amount of imbalance. The angular position is calculated using the speed measurement. Before starting the balancing process a tracking analysis (run-up and coast-down) is often performed to determine resonance-distant speed ranges for field balancing. Subsequently, the initial and the test run are carried out to determine the unbalance. Control runs evaluate the success of the performed compensatory measures.

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    Watch this video to see how a balancing process is performed: