ASTM D1831-21

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Designation: D1831 − 20 D1831 − 21
Standard Test Method for
Roll Stability of Lubricating Grease
This standard is issued under the fixed designation D1831; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers determination of the changes in the consistency, as measured by cone penetration, of lubricating
greases when worked in the roll stability test apparatus.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D217 Test Methods for Cone Penetration of Lubricating Grease
D1403 Test Methods for Cone Penetration of Lubricating Grease Using One-Quarter and One-Half Scale Cone Equipment
3. Terminology
3.1 Definitions:
3.1.1 consistency, n—of lubricating grease, the degree of resistance to movement under stress.
3.1.1.1 Discussion—
The term consistency is used somewhat synonymously with penetration. Generally, consistency refers to the worked penetration
of a grease. D217
3.1.2 lubricant, n—any material interposed between two surfaces that reduces the friction or wear between them. D217
3.1.3 lubricating grease, n—a semi-fluid to solid product of a dispersion of a thickener in a liquid lubricant.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.G0.02 on Consistency and Related Rheological Tests.
Current edition approved June 1, 2020Dec. 1, 2021. Published September 2020January 2022. Originally approved in 1961. Last previous edition approved in 20192020
as D1831 – 19a.D1831 – 20. DOI: 10.1520/D1831-20.10.1520/D1831-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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D1831 − 21
3.1.3.1 Discussion—
The dispersion of the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and other
physical forces. Other ingredients imparting special properties are often included. D217
3.1.4 penetration, n—of lubricating grease, the depth that the standard cone enters the sample when released to fall under its own
weight for 5 s. D217
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3.1.5 reduced-scale penetration, n—of lubricating grease, the depth in units of 0.1 mm that a ⁄4-scale cone or ⁄2-scale cone
penetrates the sample when released to fall under its own weight for 5 s.
3.1.5.1 Discussion—
The term reduced-scale penetration is similar to the term penetration found in Test Methods D217. However, due to the differences
in scale, the terms are not synonymous and should not be confused.
3.1.6 reduced-scale penetrometer, n—an instrument similar to that shown in Fig. 1 of Test Methods D217, designed to measure
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the consistency or hardness of semi-liquid to semi-solid materials by measuring the depth to which the ⁄4-scale or the ⁄2-scale cone
falls into grease.
3.1.6.1 Discussion—
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Either a ⁄4-scale cone or a ⁄2-scale cone can be used to determine the consistency of lubricating greases when the quantity of
sample available for testing is limited. The penetration forces are determined by the respective masses of the cones and shafts.
3.1.7 reduced-scale worked penetration, n—of lubricating grease, the penetration at 25 °C (77 °F), without delay, of a sample after
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60 double strokes in a ⁄4-scale or ⁄2-scale grease worker.
3.1.8 thickener, n—in lubricating grease, a substance composed of finely divided particles dispersed in a liquid lubricant to form
the product’s structure.
3.1.8.1 Discussion—
The thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non-soap thickeners) which are
insoluble or, at the most, only very slightly soluble in the liquid lubricant. The general requirements are that the solid particles be
extremely small, uniformly dispersed, and capable of forming a relatively stable, gel-like structure with the liquid lubricant. D217
3.1.9 worked penetration, n—of lubricating grease, the penetration at 25 °C (77 °F), without delay, of a sample after 60 double
strokes in a standard grease worker. D217
3.1.10 working, n—of lubricating grease, the subjection of a sample to the shearing action of the standard grease worker. D217
3.2 Definitions of Terms Specific to This Standard:
3.2.1 roll stability, n—of lubricating grease, the change in consistency of a sample after a specified amount of working in a test
apparatus utilizing a weighted roller inside a rotating cylinder.
4. Summary of Test Method
4.1 The Test Methods D1403 reduced-scale cone penetration of an approximately 50 g aliquot of lubricating grease is determined.
The grease is then subjected to low shear at 20 °C to 35 °C for 2 h 6 5 min in a standard roll stability apparatus, after which the
reduced-scale cone penetration is measured. The difference between the reduced-scale cone penetration before working and the
reduced-scale cone penetration after is used as a measure of the effect of low shear working on grease consistency. The same scale
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cone, either ⁄4-scale or ⁄2-scale, should be used before and after shearing the grease sample in the roll stability test apparatus.
5. Significance and Use
5.1 The roll stability test is widely used in specifications. Test results are significant insofar as they can show a directional change
in consistency that could occur in service. No accurate correlation is established between the test results and shear stability
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