Case 1: Cement Roller Press – Motor Bearing Failure

1. Sensor Layout Diagram for Measurement Points

2. Platform Failure Analysis

The loaded-end measurement point of the calender roll motor shows an anomaly; the spectrum reveals a prominent abnormal signal between 3,500 and 5,300 Hz, with peak intervals of approximately 160 Hz. Additionally, the energy at the base of the signal shows a noticeable upward trend. These findings suggest a possible motor bearing failure or inadequate lubrication.

3. Diagnosis Conclusion and Recommendations

Through system fault prediction analysis: Vibration trends are stable with no significant fluctuations. The unit can continue operating under monitoring, and it is recommended to listen to the bearing sounds—this provides an opportunity to inspect the bearing condition.

4. User Maintenance Confirmation

The customer subsequently conducted an on-site inspection of the equipment, during which unusual noises were detected from the motor bearings. Upon disassembling and inspecting the motor, it was discovered that the outer raceway of the motor bearing was damaged.

Case Two: Ball Mill-Gearbox Mechanical Looseness Causes Improper Meshing Fault

1. Sensor arrangement at measurement points

2. Platform Failure Analysis

Analysis of the output-side data from the pinion gear reveals that the RMS speed is showing an upward trend. A detailed spectral analysis indicates that the spectrum is dominated by the gear meshing frequency of 57.8 Hz and its integer multiples. This suggests that there may be poor meshing between the pinion and gear, or insufficient structural stiffness, leading to significant gear mesh frequencies and their harmonics.

Small gear output-side vibration Trends and Waveform Spectrogram

3. Diagnosis Conclusion and Recommendations

After systematic analysis and diagnosis, it was determined that there is either improper meshing between the large and small gears, or insufficient foundation stiffness. It is recommended to take the opportunity to inspect the backlash in the gear mesh as well as the wear condition of the gear surfaces, and also to check the tightness of the foundation bolt connections.

4. User Maintenance Confirmation

On March 17, an on-site inspection revealed that all anchor bolts of the bearing housing and the upper and lower bolts of the bearing cover were loose. After maintenance and repairs, the vibration level dropped from the original 27.78 mm/s to 5.69 mm/s. Additionally, the gear meshing frequency at 59.5 Hz and its corresponding harmonic vibration values significantly decreased, with the overall vibration trend now stable.

Trend Changes After Processing on the Output Side of the Pinion Gear

5. Post-event feedback recognition

Case Three: Conveyor Belt - Gear Failure

1. Sensor arrangement at measurement points

2. Platform Failure Analysis

An analysis of the measurement points at the input end of the gearbox reveals numerous peaks below 1400 Hz in the frequency spectrum, with most of these frequencies spaced approximately 24.67 Hz apart. This suggests that the observed frequency may correspond to the equipment's rotational speed. However, without specific equipment parameter information, a more detailed analysis cannot be conducted at this time.

From the time-domain waveform, it can be observed that there are clearly periodic impact signals, with the maximum amplitude reaching 40 m/s². Combined with the spectral analysis, it is suspected that the gearbox may have gear-related faults, such as pitting on the tooth surfaces, wear, or even tooth breakage.

3. Diagnosis Conclusion and Recommendations

After systematic analysis and diagnosis: Gear faults such as pitting, wear, and tooth breakage have been identified. It is recommended to inspect the gear meshing clearance and tooth surface condition in the near future.

4. User Maintenance Confirmation

In April, users conducted a shutdown inspection of the equipment and discovered noticeable wear on the tooth surfaces of the first-stage input gear, as well as spalling at the gear tips. (No on-site photos were provided.)