Grease Soap Strength

As far the Knowledge goes the quality of additives as well as the process parameters during the grease making, makes the difference in the performance parameters of the grease and its also always true that Performance tests may not be exact replica of the field trial its just indicative of what is likely to come.
Secondly the variation in the operating paramter is another factor.
If you can provide more data on the stands like is it a CRM or HSM it may be of some use to get into the finer details.
regards

Arupanjan Mukherji

Jimmy,

The values of

1.4-ball EP weld point Load wear index vide ASTM D 2596
2.4-ball wear AWSD vide ASTM D 2266

should give an idea of the probable failure point. Rather than go into the fibre chemistry performance values should give a better comparision. Needless to say, actual working conditions are unlikely to be replicated but using performance data will the user to extrapolate and arrive at changeover periods.


Hussam Adeni

In CRM the coolant, as well as in HSM application the roll cooling water,plays a vital role and there is a test designed by Voest Alpine where they mix water with the grease and performs the roll stability test to get an Indication of performance IN A LAB.
Its basically the hygroscopic nature of the grease or the greases behavior in presence of water which can be SIMULATED as another bench test for the application.
The details can be discussed later.

Arupanjan Mukherji

We tested both greases by water by Karl Fisher and the results were less than 0.1 % which is not at the origin of the liquefaction of the grease.

The problem is that the soft grease will run out through the seals. We can easily find cheap lubricating oil with high 4 ball wear or 4 ball weld point, but it will leak out.

Dear Jimmy
agrred on the point of oil and running out or leaking past seals.
The point I am trying to make is roll stability modified test, according to voest alpine which may be the solution if you are particular about the test.
But if you look at the solution- Li complex, Li ca mixed soaps or Ca sulphonate greases are good mill strand greases and base oil viscosity of 320 or460 cst@40c is ok - ofcorse look at the DN Factor at last strand

Arupanjan Mukherji

Hi Jimmy,
My 2 cents worth....

How about the NLGI standard cone penetration test to determine the consistency, it uses a 60 stroke procedure to "work" the grease to overcome the tendency of a grease to thicken up when it settles. There is an option to extend the number of strokes, to 100,000 or 200,000 if you choose. Although this in and of itself will not prove the stability of the thickner system it should give you a feel for what is suitable for a test.
A few years ago SKF did some testing on 6-8 of the same 12 hydrox....greases with the same ISO viscosity but different manufactrers base oils. They took this grease and soaked some new bearings at ~160F for a day and then inspected the bearings some were so corroded that they could not be recommended for usage, kind of makes you wonder about QA doesn't it. They did another test in the railway bearing test machine ??VF-1?? or something like that and again used several different 12 hydrox.... with the same base oil ISo grade and family "group2" and the bearing wear results urer like night and day.....

good luck....

I wonder wheather cone test can differentite shear stability of the greases and so also SKF Tests like FE8 and FE9 TESTS can be repeated in own labs or not
But FE8 AND FE9 test gives fairly large idea of shear stability but are expensive tests.
Highebase oil viscosities of 320 and 460 will perform better with lesser thinning 460 is ok and 680 is bit on the higher side.

Arupanjan Mukherji

Dear Jimmy,
The structural stability of the greases is generally indicated by Mechanical stability/ roll stability tests. For high temperature application there is ASTM D 3336 test at 149 degree, 177 degree Calso.
In the shear stability test differnce in penetration values between 6o strokes and 100,000 strokes is calculated .Higher the value poor is the stability.Same is for roll stability.Before and after the tests penetration is determined.
Now 2 greases can have same penetration 60 strokes.But different after 100,000 strokes.
The stability of the grease mainly depends upon type of soap and manufacturing process.Thats why grease making is an art and its important.
There are also company specific grease tests like SKF R2F/ SKF V2F and FAG tests to study the stability of greases.