The American National Standard classifies rotors into groups in accordance with their balancing requiements,establishes methods of assessment of final unbalance,and gives initial guidance on the establishment of balance quality grades so that,ultimately,balance quality grades can be established for all types of flexible rotors.
All rotors are therefore classified to indicate which can be balanced by normal or modified rigid rotor balancing techniques and which rquire some form of high-speed balancing.Classification of rotors into different categories permits the use of simplified balancing methods for some rotors.For all other rotors,suitable balancing methods are recommended.
As in the case of ANSI S2.19-1975,this American National Standard is not intended to serve as an acceptance specification for any rotor group,but rather to give indications of how to avoid gross defiencies as well as exaggerated or unattainable requirements.Nevertheless,it may serve as a basis for more involved investigations,for example when a more exact determination of the required balance quality is necessary.If due regard is paid to the specified limits or methods of manufacture and balance,satisfactory running conditions can most probably be expected.However,there may be cases where deviations from this standard may be necessary.