Mohammad Hassan Kargozarfard
Ahmad Hossein Asefinejad

Imbalance is one of the leading causes of vibration in rotating equipment. In general,the imbalance will arise from the mismatch of the axis of the center of gravity (notonly the center of gravity) of a rotor on its rotation axis. This defect is usuallymisdiagnosed with other common defects such as loose bearings or problems suchas rotor buckling or misalignment. Therefore, in the major repairs, the last step is thebalance operation, which is usually done in the workshop and on the balancemachine; Because its issues such as non-uniform wearing, changing the shape of therotor during repairs, scaling and their local separation cause buckling, and theychange the balance of the rotor during the repair period and therefore increase thevibration of the equipment. Hence, to prevent these cases, balancing the equipmentis considered the last stage of repairs. Based on the form and amount of thismismatch, many different imbalances are created, which factors such as theflexibility of the rotor, the length and radius of the rotor, mass distribution along thelength of the rotor, and the imbalance intensity (which is proportional to the secondpower of the rotor rotation speed) is effective in determining the imbalance type.