The motor is experiencing vibration issues – how to resolve them?

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How can we address the issue of motor vibration? When a phone experiences vibration problems, we need to take action to resolve them. So how should we deal with this issue? Below, the staff from Kunshan Litaite will explain it to you: 1. Disconnect the motor from the load, run the motor without a load, and measure the vibration levels. 2. Check the vibration level at the motor’s footings. According to the national standard GB10068-2006, the vibration level at the footing area shall not be greater than 25% of the corresponding vibration level at the bearing location; if this value is exceeded, it indicates that the motor foundation is not a rigid one. 3. If only one of the four feet, or two diagonally opposite feet, exhibit excessive vibration, loosen the foot bolts; the vibration levels will then become normal. This indicates that the pad under that foot is not properly secured. When the foot bolts are tightened, it causes deformation of the base, resulting in vibration. Secure the pad properly, realign it, and then tighten the foot bolts again. 4. Tighten all four foot bolts on the base completely; yet the vibration level of the motor remains above the acceptable range. In this case, check whether the coupling installed on the shaft extension is flush with the shaft shoulder. If it is not flush, the excitation force generated by the excess keys on the shaft extension can cause the motor to vibrate horizontally beyond acceptable levels. In such cases, the vibration level does not increase significantly; often, the vibration level decreases after connection to the main unit. The user should be persuaded to use it. During factory testing, bipolar motors are equipped with half-keys in the shaft extension keyways in accordance with GB10068--2006. Extra keys will not add additional excitation force. To handle it, simply trim off the excess length of the extra keys. 5. If the vibration of the motor during no-load operation is within acceptable limits, but it exceeds the limit when under load, there are two possible reasons: one is a large alignment deviation; the other is that the phase of the residual imbalance of the rotating component (rotor) of the main unit overlaps with that of the residual imbalance of the motor rotor, resulting in a high residual imbalance at the same position for the entire shafting, and the resulting excitation force causes vibration. At this point, the couplings can be separated, either coupling can be rotated 180°, and then the machine can be tested again – the vibration levels will decrease. 6. If the vibration velocity (intensity) is within limits but the vibration acceleration is excessive, the bearing must be replaced. 7. Due to their poor rigidity, the rotors of two-pole high-power motors can deform if not used for an extended period of time; this may lead to vibration when the motor is started again. This is a result of improper storage of the motors. Under normal circumstances, during storage, two-pole motors… The motor should be turned manually every 15 days, with at least 8 full rotations per turn. 8. The vibration of the motor with sliding bearings is related to the assembly quality of the bearing shells; it is necessary to check whether there are any high points on the bearing shells, whether there is sufficient oil supply to them, the tension of the bearing shells, the clearance between them, and whether the magnetic centerline is appropriate. 9. Under normal circumstances, the causes of motor vibration can be simply determined by examining the levels of vibration in three directions: high horizontal vibration indicates rotor imbalance; high vertical vibration suggests that the mounting foundation is not level or of poor quality; high axial vibration points to poor quality in the bearing assembly. This is merely a simple assessment; the true cause of the vibration must be determined by considering the actual conditions on site and taking all the factors mentioned above into account. 10. For Y-series box-type motors, special attention should be paid to axial vibration. If axial vibration is greater than radial vibration, it can cause severe damage to the motor bearings and lead to shaft seizure. Pay attention to monitoring the bearing temperature; if the positioning bearings heat up faster than the non-positioning bearings, the machine should be stopped immediately. This is axial vibration caused by insufficient axial stiffness of the base, and the base should be reinforced. 11. After dynamic balancing of the rotor, the residual imbalance in the rotor is fixed there and does not change; moreover, the vibration of the motor itself does not vary depending on location or operating conditions, so the vibration problem can be resolved at the user’s site. Under normal circumstances, there is no need to perform dynamic balancing on the motor again after maintenance, unless in very special cases such as flexible foundations or rotor deformation, in which case on-site dynamic balancing or returning the motor to the factory for treatment is required.