Let’s talk about wear scar diameter.

[Austinowa]

Hey guys I have been looking at the product data sheets of different greases and their specs, and something I discovered caught my eye with the 4 ball weld test and wear scar or astm d2596.

When looking at valvoline cobalt data sheet they list their wear scar at 1.15mm which appears much higher than other greases similar. However looking over Schaeffers 219 grease their product sheet calls out .41 mm wear scar but specs astm d-2266 and lists wear scar at 40kg. Also Texas refinery corp’s crown and chassis 880 grease shows theirs astm d-2266 at .33mm.

After looking at cobalt again it shows their test being done at 200kg. When multiplying by 5 to bring the weight up to 200 the scar you get 2.05mm. Now I’m sure that is not a perfect comparison but I have not been able to find any other grease listed their wear scar rating at 200kg.

I was curious if anyone found another grease list there wear scar using d-2266 and 200kg. Just something I discovered looking through pds’s.

Anyways thanks guys really enjoy the forum!

 

[FowVay]

You're comparing two different test methods. Wear scar for the Schaeffer's and Texas Refinery Corp. are measured using ASTM D-2266. The Valvoline Cobalt is publishing their test date from the ASTM D-2596.

There is likely some discussion of the two methods on this forum that you could research.

 

[RDMgr]

The test specimen configuration is the same for both the wear and EP tests.

The ASTM D2266 Four Ball Wear Test is run at 1200 rpm @ 40 kgf applied load @ 75°C for 60 minutes. The reportable result is the average scar diameter in millimeters.

The ASTM D2596 Four EP Test pertinent test data are Weld Point in kgf, Load Wear Index in kgf and the Last Non-seizure Load in kgf. Load Wear Index is based on the average wear scars at several sequential applied loads, up to 800 kgf, each running for 10 seconds at 1770 rpm until failure (weld point).

The tests look at completely different lubricant properties.

 

[Austinowa]

Thanks for the responses, interesting after ready your comments I looked at the product data sheet for cobalt and they list it as “load wear index scar”.

Looking around I don’t see any other grease specs listing the load wear index scar. Even googling load wear index scar brings up very little information besides the actual test machines and instructions.

Thanks for clearing that up it makes a lot more sense!

 

[kschachn]

Also some tests are part of a qualification of the lubricant and aren't necessarily intended to be used as an isolated property, nor are they particularly informative or predictive of the final performance.