hi all

We are using a 990kw motor running at 1000rpm, it drives a crusher rotor by belt drive.Motor NDE brg is FAG NU224 and DE FAG NU226 and brearing generating noise , we are greasing every once in a 3 month. My question is that greasing period is correct or i have to change my greasing period.....? I hope i ll get good response from you thanks in advance.

We grease ours about once every 6 months.They range from 10 hp to 1500 HP. We have only had 2-3 true bearing failures over 18 years.They started out every 3 months but the motors were filling with grease.So switched to 6 months.Seems to work OK for us.
Mike

I would recommend you adopt a condition based greasing method. By that I mean you would take either HFD data and trend the overall or use ultra sound and monitor the decibel level. Grease only until the data is back to normal.

Veer,
Check out SKF site:
http://www.skf.com/skf/productcatalogue/calculationsFil...rodid=&action=Calc15

This is a good article here, Most say to pull the drain plug and clean the hole and grease untill fresh grease comes out. Some say use High frequency readings to grease by. Realistically I can't do either of these. To pull the drain plug requires the motor to be locked out and guard removed. No time for this on mill shutdowns. Using hi frequency takes a good bit of time as well, even though it still requires pulling the plug and regreasing that way. We have over 500 motors and had to reach a happy medium so we grease every 6 months so many shots for certain size motors I forgot what they are. If the bearings are open such in large DC motors this works well for us. Some motors may have shielded or sealed bearings. You may not really know for sure, but you still need to grease them.Sometimes you have to do the best you can with the time and resources you have.

http://www.reliabilityweb.com/art06/motor_greasing.htm

Having worked in a couple of motor repair shops for many years it was an accepted practice to put shielded bearings in all motors unless otherwise specified by the customer. To put an open bearing or to remove a shield was done only upon request and not many companies specified how they wanted their bearings installed. So unless you have specified what you want, it is possible that you are only pumping grease into the windings. And I have disassembled many motors that the windings were saturated with grease.
I would suggest that anyone who wants their motors to be greased on a scheduled basis to generate a spec sheet that spells out to the vendor exactly what you want. Otherwise you will get what is common to the particular shop.
Now that I am involved with vibtration analysis, I feel even stronger about what should be speced out to your motor, or driven equipment vendor. I was always impressed by the customers who wanted their sheilds removed, or wanted to know the number or rotor bars and stator slots, the name and number on the bearings installed and any other pertainent information that a vibration analysis would find usefull.
If you do not have a spec sheet that you require a vendor to fill out, I would seriously look at incorporating that into my PDM program.
Greasing is a good thing but be aware, you can do more harm than good if you are not careful. Over greasing was describe to me by a vendor who sold grease as over greasing was like trying to run in water.
Mike makes a good point about removing the drain plug and how that is not something that can be done without shuting down and locking out. If there is one thing that I have found that is common to all industries, they do not like to shut down. One thing we had started doing on all motors was to put grease relief fittings in the drain holes. Just a little pressure will allow the grease to push out of the relief fitting.
Good Luck,
Ronnie

Mike,
Your situation sounds appropriate for pressure relieving drain plugs. There are links at this thread.

http://maintenanceforums.com/eve/forums/a/tpc/f/3191034...841028563#4841028563

In some motors, I have seen draw-out type grease drain plugs, which extend beyond the motor frame. It is basically a removable tube with its top half cut off inside another tube fixed to the bearing housing/stator frame. Such draw-out type does not require the motor to be stopped for removing the excess grease.

Excess greasing harms the bearing as well as the windings. I would use bearing temperature/noise as a guide for regreasing.

Thank you all guyes for your valuable tips

I prefer to use an Ultasonic listening device while greasing a bearing. (currently using the UE 10000) You can hear the the grease enter the bearing and quiet down, this prevents over greasing. After greasing several motors I will go back and listen to the bearings again. If a bearing becomes noisy again right away it is usually an indication of a stage 1 failure. I have found vibration analysis will pick up this noise as well, using Spike Energy or PeakVue.