STP1564

    Die-Extrusion Method for Comparing Changes in Grease Consistency and Flow Characteristics

    Published: Nov 2013


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    Abstract

    The long-standing and sole method for determination of grease consistency has been the worked (and unworked) cone-penetration values. The 60 double-stroke worked penetration value, by an ASTM method, has served as the National Lubricating Grease Institute (NLGI) grade, for the purpose of specifying commercial classes of consistency. These consistency values have been effective for machine and lubrication system designers, as well as for grease manufacturers, for the purpose of matching up the right consistency of grease for a given equipment application. However, once the grease is in service, the cone-penetrometer test is no longer a viable method to evaluate changes in consistency caused by aging, mixing of greases, contamination by solids or liquids, oxidation of the grease, or other changes in the physical characteristics related to rheology and flow. In this regard, it has been difficult to establish and adopt in-service grease-analysis methods that adequately address adverse changes in consistency.

    Keywords:

    grease, consistency, in-service testing, cone penetration


    Author Information:

    Wurzbach, Richard
    MRG Laboratories, York, PA

    Williams, Lisa
    MRG Laboratories, York, PA

    Wurzbach, Richard
    MRG Laboratories, York, PA

    Williams, Lisa
    MRG Laboratories, York, PA


    Paper ID: STP156420130001

    Committee/Subcommittee: D02.96

    DOI: 10.1520/STP156420130001


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