How to Determine the Consistency of Grease using NLGI

Here at HTS Spares we are proud to be a leading supplier of grease products to the construction industry in the UK. We stock a large selection of high performance greases, suitable for a wide range of agricultural and industrial applications, including: wheel bearings, CV joints, pins, bushes, hydraulics and mechanical components.

Greases are measured by NLGI consistency. The NLGI consistency number (also referred to as 'NLGI grade') expresses a measure of the relative hardness of a grease used for lubrication, as specified by the standard classification of lubricating grease established by the National Lubricating Grease Institute (NLGI).

The consistency is measured using the test defined by standard ASTM D217 - 'Cone Penetration of Lubricating Grease'. The penetration test measures how deep a standard cone falls into a grease sample in the tenths of millimeters. Each NLGI grade corresponds to a specific worked penetration value range.

NLGI's classification defines nine grades, each associated to a range of ASTM worked penetration values, although some grease suppliers use descriptions such as NLGI Number 1.5, which indicates that the grease is between NLGI Numbers 1 and 2.

Below is the NLGI Consistency chart which helps us and our customers quickly determine the consistency of a particular grease, using a common food substance as a comparable.

It is important to note that the NLGI Consistency Number is just one factor in determining the suitability of a grease to a specific application. Other properties such as structural and mechanical stability, apparent viscosity, resistance to oxidation must also be considered. If you are unsure which grease will best suit your application, please do contact our team, we have a number of product specialists who will be happy to help and advise.

Shop our range of plant and machinery grease products here.