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ASTM D217 - Cone Penetration of Lubricating Grease

Significance and Use

5.1 These cone penetration tests not only evaluate the consistency of lubricating greases over the full range of NLGI numbers from 000 to 6, but also evaluate the consistency of stiff greases having penetration numbers less than 85. In contrast, Test Method D937 is aimed at petrolatums and Test Method D1403 uses less precise 1/4 and 1/2-scale equipment intended for use when the sample quantity is limited.

5.2 Cone penetration test results provide one measure of the consistency of a grease. Worked penetration results are required to determine to which NLGI consistency grade a grease belongs. Undisturbed penetration results provide a means of evaluating the effect of storage conditions on grease consistency.

5.3 Although no correlation has been developed between cone penetration results and field service, the cone penetrations obtained by the four procedures are widely used for specification purposes, such as in users' material specifications and suppliers' manufacturing specifications.

1. Scope

1.1 These test methods cover four procedures for measuring the consistency of lubricating greases by the penetration of a cone of specified dimensions, mass, and finish. The penetration is measured in tenths of a millimetre.

NOTE 1: The National Lubricating Grease Institute (NLGI)2 classified greases according to their consistency as measured by the worked penetration. The classification system is as follows:

NLGI                                     Worked Penetration Range,
Consistency Number              25 °C (77 °F)            

000                                               445 to 475

 00                                               400 to 430

  0                                               355 to 385

  1                                                310 to 340

  2                                               265 to 295

  3                                               220 to 250

  4                                               175 to 205

  5                                                130 to 160

  6                                               85 to 115

1.1.1 The procedures for unworked, worked, and prolonged worked penetration are applicable to greases having penetrations between 85 and 475, that is, to greases with consistency numbers between NLGI 6 and NLGI 000. An undisturbed penetration test, described in Appendix X1, is similar to the unworked penetration test.

1.1.2 The block penetration procedure is applicable to greases that are sufficiently hard to hold their shape. Such greases usually have penetrations below eighty-five tenths of a millimetre.

1.1.3 Unworked penetrations do not generally represent the consistency of greases in use as effectively as do worked penetrations. The latter are usually preferred for inspecting lubricating greases.

1.2 None of the four procedures is considered suitable for the measurement of the consistency of petrolatums by penetration. Test Method D937 should be used for such products.

1.3 The dimensions of the equipment described in these test methods are given in SI units as the primary unit of measure with equivalent imperial units as accetpable alternatives where applicable. In cases where equivalent SI conversions are not known, notes are added for clarification. Temperatures and other dimensions are given in the preferred SI units; the values shown in parentheses are provided for information.


Extracted, with permission, from ASTM D217-19b Standard Test Methods for Cone Penetration of Lubricating Grease, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International, astm.org