Planning to visit cement mill day after to handle high axial vibs on a motor-gearbox driving the kiln mill. I made a visit to this site one month back for condition monitoring data collection. but during that time the motor was running at 1275 rpm less than its rated speed.attached is a 2 page report.
y'day i got a call from client saying that the axial vibs are high on the Gearbox assembly.
The vibs are high on the gearbox input bearings in the axial direction reaching 25-30 mm/sec when the speed was increased. Radial vibs are OK. But I have not got the data so far from the site.
The client says alignment was redone, gearbox internals, bearings were inspected and no damage found. Cleint says there is no change in the process parameters during raise in vibs. Can you send me your inputs?
I have planned for the following. please correct me if i am wrong,
1.Take the vib data at different speeds in HVA directions on the total system
2.Decouple and run the motor in the solo condition.
3.If unbalance induced vibs observed in the spectrum, balance the motor at site conditions at rated speed.
4.Check for any soft foot conditions.
5.Bump test on the motor bearings, coupling, gear internals
6.Study the gearbox drawings
7.Take data in load and no load conditions.
In your opinion and experience what may be the reason for high axial vibs on the gearbox input bearings while the radial vibs are OK.
Do gear internals (bull gear, pinion) natural frequency matching with the rated speed of motor...?? waiting for your valuable inputs.