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ASTM D2596 - Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method)

Significance and Use

5.1 This test method, used for specification purposes, differentiates between lubricating greases having low, medium, and high level of extreme-pressure properties. The results do not necessarily correlate with results from service.

5.2 It is noted that lubricating greases that have as their fluid component a silicone, halogenated silicone, or a mixture comprising silicone fluid and petroleum oil, are not applicable to this method of test.


1.1 This test method covers the determination of the load-carrying properties of lubricating greases. Three determinations are made:

1.1.1 Load-Wear Index (formerly called Mean-Hertz Load), 1.1.2 Weld Point, by means of the Four-Ball Extreme-Pressure (EP) Tester, and

1.1.3 Last nonseizure load (LNSL).

Extracted, with permission, from ASTM D2596-20 - Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International,