Compatability test of greases

Franky,

I do not recall seeing ASTM test method for compatibility of Greases. I wonder if it exists.

Hussam Adeni

I agree with Adeni and I think it is done with a 50 -50 mixup of grease and subjecting to worked penetration test to see the hardening and sofeting of the mixture and then see the sample is within the prescribed limit or changing consistency, and they are according to ASTM methods.
regards

The generally accepted testing (basic) for grease compatability is to mix the 2 samples 25 - 75
50 - 50
75 - 25
and to conduct the ASTM D1831-94el Standard Test for Roll Stability of Lubricating Grease
and then to conduct the ASTM D217-97 Standard Test for Cone Penetration of Lubricating Grease.

Now comes the fun part. At what level or percentage of change are you as the end user going to accept/reject. And based on what performance criteria? The thinking is that if the 2 lubes are compatable then there will be a small change in the grease consistency. If there is a big change after the 2 hour test then you would assume that the 2 lubes are incompatable.

regards.....

Allan

Should we also consider drop point ' C of the mixture ?

What percentage Change in penetration number is acceptable? Should it stay in range of NLGI specification or 5% change of the individual grease is tolerable?

Your views please

Franky

You are right.The grease compatibility tests are done as per ASTM D 6185 in which Penetration, drop point and high temperature tests are done on 90:10,10:90,25:75,75:25 and 50:50 mixtures of greases.Depending upon the criticality of application Tribology tests are also recommended.
Normally,if the bases are same they should be compatable.
There is also a chart showing which grease is compatable with other grease.
Thanks

Vijay

That's what I was looking for , as customers need confirmation.

Thanks
Franky