How to choose the balance mode of rotor is a key problem. The choice of the aircraft vibration balance instrument has such a principle: as long as meet the needs of the rotor balance after the use of the premise, can do static balance, do not do dynamic balance, can do dynamic balance, do not do static and dynamic balance. The reason is very simple, static balance is easier to do than dynamic balance, save effort, save cost.

Modern, all kinds of machines used by the balance method, such as single side balance (also known as static balance) often use the balance frame, double side balance (also known as dynamic balance) use all kinds of dynamic balance testing machine. The static balance accuracy is too low and the balance time is long. Air vibration balancing instrument testing machine can be well to balance the rotor itself, but for the rotor size is large, often need different size of dynamic balancing machine, and when the test still needs will be removed from the machine rotor, such obvious is neither economic, is also very work (such as steam turbine rotor after overhaul). In particular, dynamic balancing machine can not eliminate the system vibration caused by assembly or other follow-up components. Balancing the rotor under normal mounting and operating conditions is often referred to as "field balancing".

Field balance can not only reduce the amount of labor in dismantling rotor, no longer need dynamic balancing machine; At the same time, due to the difference between the test state and the actual working state, it is beneficial to improve the precision of measuring unbalance and reduce the vibration of the system. According to international standard isol940-1973 (E) of aerial vibration balance instrument, precision rotor with balance accuracy of G0.4 must be balanced on site, otherwise balance is meaningless. Modern dynamic balancing technology was developed with the appearance of steam turbine at the beginning of this century. With the rapid development of industrial production, rotating machinery is gradually developing in the direction of precision, large scale and high speed, making the problem of mechanical vibration more and more prominent. The violent vibration of the machine will bring a series of harms to the machine itself and its surroundings. Although the causes of vibration are various, it is generally believed that "unbalanced force" is the main cause. According to statistics, about 50% of the mechanical vibration is caused by unbalanced force. Therefore, it is necessary to change the mass of the moving part of the rotating machine to reduce the unbalanced force, that is, to balance the rotor.