POST

EMDS was called to evaluate the E51FN05 Fan, at an aggregate plant, which had been running smoothly until a defect in the fan bearings necessitated their replacement. Continued abnormal motion was detected around the unit, prompting EMDS to acquire and analyze Motion Amplification Video, alongside traditional velocity and acceleration vibration data.
The motor and fan were mounted on a substantial concrete base, supported by below- grade caissons, and surrounded by a concrete apron serving as a walk and work platform. Moisture pressing out around the expansion joints while the fan was operating, and noticeable vibrations underfoot raised concerns. An earlier attempt to add mass to the apron with bagged cement had been unsuccessful in settling the vibration. Horizontal and vertical vibration data were collected on the motor and fan bearings, as well as in the axial direction. Additional data were gathered at multiple points on the concrete structures, from the sole plates to ground level. Amplified motion videos were then taken at several points on the machine. Analysis revealed that the motor velocity was higher in the horizontal direction, peaking at 0.127 in/sec on the motor outboard bearing, with most activity occurring at 1X running speed and some harmonics due to base transference from the fan bearings. Similarly, the fan was most responsive in the horizontal direction, with the highest velocity at 1X rotational speed on the fan inboard bearing, reaching 0.285 in/sec at 853 CPM. Running speed harmonics in the spectra indicated bearing looseness, with light once-per-revolution impacts in the time domain.
The Amplified Motion Camera showed that the motor, sole plate, and concrete supports moved as a monolithic structure. Videos, too large for email, were shared via an online service. Despite the exaggerated motion in the videos, movement down to the gravel was discernible. Vibration measurements on the concrete support structure, from the sole plate to ground level, indicated velocities of 0.10 in/sec peak at ground level.
The conclusion was clear: bearing looseness was present on both fan bearings, needing resolution before any Operational Deflection Shape (ODS) modeling. Close monitoring of the bearing looseness was advised to prevent unexpected failure. Additionally, a non-destructive test was recommended to examine the earth and caissons below the concrete support structures. Through meticulous analysis and advanced technology, EMDS provided a comprehensive solution to the vibration issues, ensuring the E51FN05 Fan could return to smooth operation.