Originally Posted by eng.farid.ahmed

Hi,

I'd be grateful to you if you could please kindly share our experiance

to solve a problem in a bearing lubrication.

The problem is:

The grease converts into oil and the oil escapes from the bearing housing.

Notes:

The application is a fan.

The bearing type is SKF 22218 EK/C3.

The grease type is Mobilux EP2.

The bearing speed is about 1680 rpm.

The re-lubrication grease quantity is about 40 grams.

The re-lubrication interval is about 25 days.

The temperature for the bearing housing is about 60-70 degrees Celsius.

Kindly please let us know Why does the grease convert into oil? and what are the factors which lead to convert the grease into oil?

How can we avoid this problem?

Thank you.

Marhaban,

About your SKF 22218 EK/C bearing;

you are using the wrong grease and the seals may be shot.

you need to use polyurea based high temperature grease

not the EP-2 grease. ■

Originally Posted by eng.farid.ahmed

Dear Lzaharis,

Grateful thanks for replying and advice.

For grease (Mobilux EP2), the recommended operating temperature range is from -20ºC to 130ºC from EXXONMOBIL.

http://www.mobil.com/USA-English/Lub...obiluxEP.aspx

Furthermore, the bearing housing's temperature doesn't increase above 70 degrees Celsius.

Moreover, MOBILUX EP2 is recommended grease for the fan bearings from FLSmidth at low temperature range, but if the bearing temp raises to 100 degree Celsius the recommended grease is Mobilith SHC 100 (high temp grease), so why is the grease wrong?, and why does the grease convert into oil?

Thank you.

Marhaban,

The rotor speed is the issue and the bearing is warmer because of the 1,680 R.P.M., rotor speed,

switch to the mobilith SHC 100 or the Polyurea based grease recommended by Falk

and you should have no further problems. ■

Originally Posted by eng.farid.ahmed

Dear Lzaharis,

We changed the grease from Mobilux EP2 to Mobilith SHC 100, and we found that no problems in the bearing.

But I'd like to tell you that, the bearings worked at 1,680 R.P.M. for a year with (Mobilux EP2) without any problem, why suddenly the grease converts into oil?!

Thank you.

Greetings and salutations,

The only plausible reason(s)

Would be that the ambiant temperature in the storage area for the cases of grease

is very hot or it could be that the bearing rollers have become smaller in diameter from wear.

The rollers have probably traveled around the globe 100 times or more in actual distance traveled in the

scheme of things. ■

You might want to consider an inexpensive vibration analyst tool and start recording vibrations on a monthly basis (or weekly if fan is critical equipment). A simple graph of the data will give you a good baseline now that the bearings are new. Over time you will see the graph start to increase in vibration as the bearing wears. Take axial and radial measurements on each bearing - paint a dot on the spot where you take the measurements so it is consistent. Over time you will learn when the best time is to change the bearing(s). Adding temperature readings taken at the same time (on the same spots) can also be recorded and used as an indicator of potential problems.

This is a simple PM that can save you many hours of downtime due to unexpected failure. Your bearing changes can then be easily planned and not done during an emergency shutdown.

Best of luck. ■

Dear Farid Ahmad;

Lubrication problem can be overcome by using the greese carefully. Always apply cold greese to lubricate.

If it is hot it melt down and become the oil. ■

Originally Posted by eng.farid.ahmed

Dear Lzaharis,

We changed the grease from Mobilux EP2 to Mobilith SHC 100, and we found that no problems in the bearing.

But I'd like to tell you that, the bearings worked at 1,680 R.P.M. for a year with (Mobilux EP2) without any problem, why suddenly the grease converts into oil?!

Thank you.

Hi guys,if anybody have buy skf bearings from Hongkong ■

Originally Posted by eng.farid.ahmed

Dear Lzaharis,

We changed the grease from Mobilux EP2 to Mobilith SHC 100,

and we found that no problems in the bearing.

But I'd like to tell you that, the bearings worked at 1,680 R.P.M. for a year

with (Mobilux EP2) without any problem, why suddenly the grease converts into oil?!

The Mobilux EP2 grease lubricants componenet mixture finally reached the point

where they broke down and lost their ability to stick together and binding in the

bearing cage/they no longer were able to maintain a congealed state like warmed

Jello Gelatin left on a pavillion table in the sun.

I am very glad the change in lubricants worked out for you. ■

It will work for a while, but you might as well get ready to buy a new fan. If the bearings are making noise, putting lube on them will make them run quiet for a while, but the noise indicates the bearings are already worn, and they will only get worse.

The oil initially will loosen up and help clean up any dust in the bearings, but moving forward, now dust is going to stick to and accumulate about 10 times faster than normal to the oily surfaces. There is dry lube which can work pretty well, but like I said, if the thing is making noise, it is only going to get worse, and fans don't cost much, I would just go get a new one. ■