When a gear reducer malfunctions, the first thought might be to call a professional repairman to disassemble and repair it. However, when a machine malfunctions, we can first perform a self-check. Listening to the sound can help determine the cause of abnormal vibrations and noise during the start-up of the gear reducer motor. Let's hear what an experienced person from a gear reducer motor manufacturer has to say.
Listening to the sound mainly involves checking for any extraneous noise from the bearings. You can buy a listening rod with a resonator at one end, or use a single metal rod to listen to the sound.
(1) Listen to the noise of the bearings of the gear reducer motor .
Normal sound – without a continuous metallic sound that fluctuates in pitch.
The sound of the retainer ring is a light "chirping" sound produced by the rotation of the rollers or balls with the retainer ring, containing irregular metallic sounds unrelated to the rotational speed. If this sound decreases or disappears after adding lubricating oil, it has no impact on operation.
Crack sound – the sound emitted when cracks appear on the raceway surface, or the surface of the balls and rollers of a bearing. Its period is proportional to the rotational speed. When a bearing develops cracks, it must be replaced quickly before it overheats or sinters.
A "creaking" sound usually originates from within roller bearings. This sound typically disappears after adding lubricating oil. If a "creaking" sound occurs without accompanying abnormal vibration or temperature, the machine can still be used normally.
The sound of rollers falling—this is a sound produced by a geared motor during horizontal rotation. It is inaudible during normal operation, audible at low speeds, and particularly clear when it is about to stop. This "shell-like" sound does not hinder operation.
Dust noise – this is the sound produced when dust gets trapped between the raceway surface and the rollers or balls. After dust noise occurs, the bearing components should be disassembled and thoroughly cleaned. At the same time, remove dirt from the lubricating oil inlet and the lubricating oil injection gun to eliminate any potential causes of further blockage.
(2) Listen to the noise of the rotor of the gear reducer motor.
Rotor noise is usually fan noise and brush friction noise, and occasionally a loud sound like drumming. This occurs during sudden starts and stops, especially during frequent reverse braking and regenerative braking, because the torque generated during acceleration and deceleration causes the fit between the iron core and shaft to loosen, resulting in severe rubbing against the key.
Loose fit between the bearing shell and shaft of the coupling or pulley; worn or deformed coupling bolts; insufficient lubrication and worn teeth in the gear coupling; loose or worn belt. These factors can all cause noise in gear reducers.
(3) Listen to the electromagnetic noise of the gear reducer motor.
Gear reducers generally produce some electromagnetic noise, which disappears when the power is cut off. Most electromagnetic noise is generated by electromagnetic vibration resonating with the stator and outer stator core. Factors that significantly increase electromagnetic noise include: uneven air gap, loose core, unbalanced current, and high-order harmonic currents.
When a geared motor experiences abnormal vibration and noise upon restarting, it may not cause serious damage to the motor in the short term, but over time it will definitely have serious consequences. Therefore, we should promptly identify the cause of the abnormal vibration and noise in the geared motor and resolve it in time; otherwise, the geared motor will inevitably be damaged in the long run.
