Equipment :

Variable Speed Ball Mill ( OEM – SALA Sweden) , Power – 700 KW, Throughput – 75 T/ hr (Chromite Ore as slurry feed), RPM- 12.8 - 17 Max
Feed end Bearing (Locating ) - 239/850 K.MB.C3, Taper Sleeve –H 564124, Housing – SZA39/850-159555 with locating ring
Discharge end bearing (Floating) – 239/850 K.MB.C3, Taper Sleeve –H 564124, Housing – SZA39/850-159555
Lubrication – Continous lubrication thro' automatic lubrication system ( NLGI 2)

1) What are the parameters to be monitored i.e Vibration velocity, displacement, accleration, Crest factor .... ?

2) What should be the Fmax for Velocity , Acceleratio, Demodulation ?

3) What can be the alarm limit for such an application?
*.jpeg is Mill Schematic>>

It is a low speed machine. For slow speed measurement there are some good articles on net for bearing monitoring. Begin with a handy vibration cum spike/gE/shock pulse measurement.When suspecting some problem proceed further.
1.Velocity for such low RPM may not be that useful. You can use REBAM displacement probes from Bently for displacement measurement and flexing of bearings races and detecting the stress waves . Acceleration is the best thing and you can catch any impacting occurring in incipient stages in bearings or gears.
2.If you catch velocity for overall meaurement, it may be around 25 x. For acceleration, catch at least 6 revolutions to capture any impacting occurring in the bearing or gear boxes .
For demodulation, you can use high pass filter to filter out at least 5 th harmonic of BPFI. Low pass filter may be around 10khZ for bearings. For gears, try to capture at least 3 rd GMF.
3.For alarm limits, pl. refer Machine Dynamics August 1989 issue for bearing cap measurements.Also you may refer TSA limits of vibration in different frequency renages..
Also use high sensitivity(500 mv/g or above) accelerometers for measurement of slow speed vibration to distinguish signals from noise.
For motor go for the low pass filter above 3XRBF. You have so many measuring points. Each may require a different set up in the analyzer.

Regards.
Irshad

This message has been edited. Last edited by: AKHTAR,

HI Prabhu,
I used to monitor 9 iron ore ball-mills that range from 3000 to 5000 Hp at 15 rpm. First variable speed machine is tricky see with operation the possibility to collect the data at a fixed speed which is closer to average operation. You will need special demodulation technique for the mill’s brg (Peakvue) I don’t advice the use of high sensibility acc. it never did anything more for me as the low speed point are best diagnose in peakvue, which is high frequency demodulation. You need long waveform on low speed point to accommodate many rotations of the mills for transient and gear detection. I usually collect 8 revolutions at 4096 points of resolution. Takes a long time but it is worth the trouble. All the other points is set the same as other machine: Fmax 80 to 100 x TS with enough resolution to detect lower shaft’s speed of the component. Watch the program wizard, it’s not always perfect when it comes to data acquisition you will need to go over. Ball-mills are slow speed noisy machine but it is possible to get very accurate result if you take the time set it up properly and you have to analyse the waveform especially on gear problem.
Good luck, Marcel