These brgs are basically maintenance free

Only issue will be excessive dust ingress or operation without oil flow

What is you specific issue?

We have never changed one brg yet

Thanks

James ■

I assume that you have been in touch with FLS the OEM re the issue.

Are you sure where the TIN comes from - do you have a side drive mill with girth gear ie oil circuit is for mill slide brgs and side drive gearbox.

I am not sure of our TIN content in our oil - have not checked - but I think that you have issues to follow up.

Is the mill support foundation OK - did you have a as built survey levels. Our mill support is from one large one piece foundation for feed and discharge end. If you have two different - non connected ie separate - foundations supports for feed and discharge ends > you could have a differential settlement issue.

I am assuming that the bearings for this mill has a semi spherical knuckle support - this means that that bearing should rotate and provide full face/surface contact with the mill running face. Note that the mill will deflect under self weight etc - hence, the bearings should float and move to suit?

There should be 4 brgs per end - the 2 outer ones should be fixed and the 2 inner ones should be adjustable. The mill shell will expand in diamater when running at normla temperatures.....smalller dia. when cold and slighter larger dia. when warm. At the non drive end - if you have a side drive...the bearing high pressure oil readings should be alsmost all equal (< 20bar ) difference when running warm. If not - then you need to adjust and this may be done when running.

If you have a side drive gearbox and this is at the discharge end - then the lift effect onto the girth gear will change the warm running lift pressures...but the same sort of rule applies..

You can also look at the brgs temp when running - this ia a bit crude/dull to tell but will give a guide esp. if brg set up is really out.

The oil systems should have a conditioning pump with duplex filter to clean the oil when running - important to make sure that the filters get cleaned/changed wehn dirty and that you have a time based plant shutdown alarm if they are not cleaned/changed over. Make sure that non one has bridged this out ie removed filters and keep running.

Look at your seals area - the seals should have a very small gap when cold and should be touching when running warm - you can use an infrared gun to get running face temps when running - anything over 80-100deg C is cuase for concern. If too hot....seal rubbers will get effected.

Do not know what seal profile you have - should be a twin lip system each seal face.

Also...there should be oil wipers on the running face inside the trunnion casing to wipe oil off after the brgs/gear area to keep oil away from the seals and reduce chance for oil mirtation/dust migration past seals..

I assume that you are using mineral oil - good - but make sure that you have the right grade for your temperatures....make sure that your cooling water heat exchangers are setup right as well..oil need to stay within the right temp.......too hot means too thin and this means lower brg clearnaces

I am assuming that your pumps are all OK and set up right.

As I said - the brgs should last forever....there should not be any contact at all other than a power failure case where the mill may free swign to stattionary and there is no oil supply.

Thanks

James ■

One last point - are you sure where the tin is coming from - the oil pumps will wear as well..esp. with dust.

If the tin content is rising over time - then something is wearing.

The oil sstems have an awful lot of oil - I would think that a small amount of tin would not show up.

We monitor our systems by oil flow and brg temperatures ■

Hi

Can you pls elaborate on this comment - even a photo.

The face of the running ring is dull in appearance with a noticeable band around the centre.

Are you in contact with the OEM - we do not have them as our mill suppliers.??

The inlet side can be higher than the outlet side due to clinker temperature etc.

Do you have individial brg temperature measurement?

Do you have individual pressure reading for each bearing - you should have LP and HP feeds to each brg and in normal operation - the pressure guage on the HP side should give you the brgs pressures.

Are you sure that you have no broken LP hoses to the brgs - they typ. use flex hoses inside the casing to get to the bearings - the indication is lower LP pressures. Also...the HP line should have check valves to stop reverse flow when the LP system is running alone.

460 grade oil is fine - are you running it between 40-45deg C??

I assume that the oil system capacity is 2000 litres plus....so if you are getting high Tin - then there has to be a lot of Tin coming out.

If the foundations have settled - this can be OK as long as your brgs can accomodate the movement - they should have a semi spherical mounting face to allow tilting of the actual pad to suit the mill shell deflection etc etc.

Changing a brg is not a big deal - you need the slide frame and the jacks to suit.

Has this issue started from day one 6 years ago or just recently??

Thanks

James ■

Me again

Now you say that the issues are at the feed end...this is the floating end and you must jack the mill every 2+ hrs during cooldown for 48+ hrs to allow the mill shell to contract as it cools. If you do not, then the mill will drag across the brgs fces and this is def, not good. Pls confirm that you have this set up and is fully functional ie happends regardless of normal or crash stop.

Also.....do you have dust leakage issues at feed end eg back spilling from feed chute/inlet cone or leaking 1st compartment liner bolts...you can address these by various means and should do so.

With the seals - pls see my first post re suggestions - this is one area that you need to look at later on.

Have you taken IR temp readings across the feed end running face during operation.

Cheers

James ■

Something is not right there.

Assuming that the shell bolt leakage is not going to be an issue > you could remove/open the side door isnpection ports and inspect each brg when running....there will be oil there but it should not splash out of the casing. You will need thermal protecive gloves etc. Look at the outside and see if the oil film is not 100% across the face...what is causing the patch in the middle.?

It seems to line up with the HP port area in the brgs - maybe there could be a dam/build up of gunk in the oil recess in the brg slipper and this is causing wear.

Have you placed a straight edge across the running face of the trunnion??

I can send you photos of our brgs during installation plus doing checks when running if you like

Over to you

Cheers

James ■

Hi

I am on leave now..I will send you some photos later.

These brgs are almost indesrtructable.

The HP pumps usually do not run when in normal running mode - the HP supply line should have NRV fitted to stop oil leakage/reverse flow from the brgs area with LP supply oil. In this line - should be HP pressure guages - have you checked this and are all pressures within 20bar of each other.

Even with dirty oil - the oil film should be deep enough to let dirt particles go past these brgs...unless very big particles of dirt......

I am assuming that the discharge end is all A OK.....no issues.

Anyway , dirt is not good as we all know. Suggestions are

improve seal - see earlier post - need to set up as desribed ie small clearance when cold and trunnion to be less than 80-100deg C when running.

install a plastic bladed/counterweighter trunnion ring wipers just inside the casing near tjhe seal on the uphill outward running side...this is to get the oil off the trunnion and esp. away from the seal area ie remove the dirt magnet/attraction effect.

increase air flow suction at the feed end - to help minimise dust leakae...this can be done with plywood blanks over the fresh air intake (if you have one).....you can even look at a semi spiral blade to scoop the material into the first compartment. make sure that the mill is not overfilled or the feed control loop is not over feeding. any grinding aid injection nozzles need to be set up right to avoid back spilling

use Nitrile rubber washers on your 1st compartment liner bolts - make sure that these bolts are properly tensioned up.

make sure that you oil filter system is set up right - duplex and no one is bypassing them

consider fitting a kidney oil filter unit to the oil units - use large throw away filters - just keep filtering the oil.

Somehow - just by looking at your photos - there is a distinct mark at the centre and this seem to line up with the small recess that should be machined into the brg for the HP jacking action...maybe this is filled with dirt. You could check this - the 2 outer brgs should be rigid/fixed...the two inner brgs are adjustable - there should be a locking tabs on the outside of the brgs casing - to look the adjustment - keep track of this...lower the brgs , move away and inspect...then reinstate and then re check the HP lift pressures when running. The reason why I asked about checking the oil film across each brgs is to see that the oil film is continious across each outward running face. This check will take you 1 maybe 2 days to do...

Have you checked all the other items???

There is really not much more to it...they are simple brgs...the complicated part is the oil system LP and HP side and programming and set up the middle adjustable brgs pads.

Cheers

James ■