Testing Grease Consistency

Abstract

Because of the influential role of consistency in selecting a grease for a given application, accurate and meaningful methodologies for its measurements are vitally important. A new method, recently introduced, uses a rheometer to compress a grease sample to evaluate a relative consistency between a fresh and degraded grease; however, the results of this approach compared to a standard penetrometer and other methods of assessing consistency have not been studied. This paper takes a closer look at the relevant parameters involved in the rheometer penetration test and establishes a recommended procedure for its use. The consistency of various greases is then tested using this method and compared to results obtained from yield stress, crossover stress, and cone penetration tests. The results indicate that rheometer penetration may be used to assess the change in consistency for a given grease but should not be used to compare different greases. For this purpose, the crossover stress method is recommended, which is shown to correlate very well with cone penetration while using a simple procedure and allowing the use of a substantially smaller sample. A strong power law correlation between crossover stress and cone penetration was found for all greases tested and is presented in Figure 12.

Study of the changes in the microstructures and properties of grease using ball milling to simulate a bearing shear zone on grease

“…The storage modulus and loss modulus curves enter a nonlinear viscoelastic region after going through a linear viscoelastic region, and they intersect at a point. The lithium grease becomes fluid after the intersection point 22 , 23 . Before 12 h, the storage modulus and loss modulus of the lithium grease samples gradually decrease with increasing ball milling shear time.…”

Rheological characteristics and behaviour prediction of lubricating grease for RV reducer across a wide temperature range

“…Table 1 shows the main components of the grease and the related technical parameters. The consistency parameter is critical to the performance of the grease, and the main test to measure grease consistency is the cone penetration test given by ASTM D217 [19]. The consistency level is divided by penetration depth of the cone penetration test.…”

Role of the Measurement Uncertainty in Cone Penetration Test Results of Lubricating Grease

“…The main contributor in a CPT measurement is always determined by the skill of the operator [1]. The contributors to the uncertainty budget considered here were the results of GR&R and the results from the calibration certificate of the penetrometer.…”

“…The most frequent measurement of lubricating grease consistency is the cone penetration test (CPT) [1] [2]. CPT could be understood as a hardness measurement of the grease.…”