FORMULA for grease relubrication interval 1

[electricpete]

Various manufacturer's publish charts which can be used to determine appropriate grease relubrication interval for rolling bearings. To enter the charts we would normally need speed and bearing dimensions. Also sometimes need a load ratio or a speed ratio (actual/rated).

Are there any formula's which accomplish the same function without need for a chart. I would like to be able to do it in excel (along with calculating grease quantity, whose formula is already known).

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[gunnarhole]

Pete,

Go to the following URL,

http://www.lubriquip.com/pdf/20115.pdf

to see the lubriquip/trabon approach to calculation lubricant consumption.

Regards,

Gunnar

 

[aviat]

If you already have the charts you can determine some values from them and enter them into excel, then chart the values. Then right click line and click on trend line, select the type that fits your data, then under options select Display Equation on Chart and excel will give you the equation.

 

[Hippo41]

The charts are 'general' in nature because they have to be.

I don't believe there is any 'magic formula' that will give you accurate answers because your operating conditions are so variable, as is the quality of both products (i.e the bearings and the grease).

SKF (and others) offer the following formula

Gk = (0.3...0.5) DB x 10^-4

Where Gk = grease qty to be supplied in grammes per hour
D = Outer diameter in mm
B = Width of the bearing in mm

The only way I have seen that a large operation (steelworks) sort out their lubricant question was a concerted and joint effort between the maintenance staff, the bearing suppliers and the lubricant suppliers who all assisted in the monitoring of a specified lubricant over a period of time, under known conditions.

The end savings were huge - but it took a lot of effort, and time.

If you do produce 'the Holy Grail' you'll make a fortune!

Lester Milton
Telford, Shropshire, UK

 

[volpegrigia]

I have a Mathcad file that allows you to do this without much of a problem. Let me know if you would like it, or if you do not use mathcad, I could post the formulae so you can include them in a spreadsheet!

 

[electricpete]

volpegrigia - can you please post the formula?
thx

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