sag mill vibration

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Hello Archie,

I assume that you've checked and ruled-out the pinion and girth gear meshings, as well, correct? In addition to the excessive vibration, has the mill recently experienced any bolt breakage ('structural', not 'liner')? Owing to the severe dynamic operating nature of mill bolts, their proper preload is critical. Improper bolt preload has lead to fatigue failure and slippage - and excessive vibration. On the other hand, improper bolt preload can also lead to simple slippage if the bolts are too 'loose'.

Either extreme is quite common on mills assembled by "torque" methods without preload control. You may wish to look into this if you haven't already.

Here's an interesting Case History which describes how potential failure was averted during a Girth Gear replacement job on a SAG Mill by ensuring control of bolt preload - SAG Mill Girth Gear Repalcement

Good luck making lots of concentrate!

Can you please let us know the bearing number & sleeve details. Few months back we too had similar kind of problem in our lime stone crusher and it got sorted out after we changed the bearings and its sleeve. ( clearance were very high )

you can get the vibrations analysed and then pin point the areas where vibrations are more

probable reasons for vibrations :

1) Bearing clearances 2) type of sleeve used 3) mounting bolts getting loosened 4) motor / drive arrangements 5) structures 6) gear box condition, if any

Since you just finished with a reline, I would look closely to see if anything changed that could cause the vibration.

If this mill Trunnion is a large plain bearing I would make sure the lubrication of the bearing is taking place as before. When a heavy mill sits for an period of time the lubricant will all be squeezed out of the plain bearing. Or possibly the solid lubricant (if that is the type) will need primed with liquid or heated to start working correctly again.

Also it may be a possibility that the vibration is not originating at the Trunnion. Sometimes the source of vibration is not apparent.