Cone Penetration and Prolonged Working of Lubricating Grease


Determine the consistency and NLGI grade of a lubricating grease.

Brief Description

A cone of specified weight is allowed to fall into a lubricating grease sample at 25°C. The depth of the cone, in tenths of a millimeter, identifies the consistency of the grease. With the use of Table 1, the NLGI grade of the grease is identified from the 60 stroke worked penetration.

This test can be used to determine the mechanical stability of a grease though prolonged working, such as 10,000 or moredouble strokes using the motorized grease worker. While cone penetrations are typically conducted at 25°C,measurements can be carried out at other temperatures. About 300 grams of grease are required to conduct the ASTM D217 test. ASTM method D1403, DIN 51 804, and IP 310 describe cone penetration equipment commonly referred to as 1/2 and 1/4 scale devices for use when less than 300 grams of grease are available.

The photos depict the cone prior to release, greases of NLGI grade 2 and 3 consistencies, and a motorized grease worker.

Table 1: NLGI Classification Scale

The information presented in this article was originally derived from a publication from Mobil, and is presented here for information only. Please consult with your Certified Lubrication Specialist to ensure proper testing is done.