Experimental Observation of Thickener Effects on Grease Film Evolution

doi:10.3901/JME.2025.21.318

Abstract

Abstract: Grease thickeners exert a significant influence on the chemo-physical and mechanical dynamic properties of grease. The rheological properties of grease are measured using a rheometer, while the evolution process of the lubricating film is assessed using an optical ball-on-disc lubricating film measuring apparatus. The results indicate that the thickeners affect the grease film formation under sufficient supply conditions due to variations in apparent viscosity. Under a fixed amount of grease supply conditions, the lithium grease shows a better lubrication state than those of greases with other thickener types. By analyzing the grease rheological properties and rolling track distributions, it is observed that lubricant replenishment in grease is associated with storage modulus, elastic modulus, and shear stress at intersection points. The decrease in rheological parameters with increasing shear stress will contribute to the increase in base oil bleeding and subsequent replenishment. The tackiness of grease affects the grease adhesion on the surface and transformation between contact surfaces, subsequently determining the grease distributions. Through analysis of rolling track images, it is found that the grease distributions with finger patterns facilitate bleeding oil transportation and replenishment. Grease experiences varying degrees of shear at different distances from the rolling track, playing distinct roles in grease film formation.

Key words: thickener, lubricant reservoirs, lubrication state, starvation, optical interferometry

CLC Number:

TH117

JIN Xuyang, LI Xinming, BAI Linqing, GUO Feng, GERHARD Poll, ZHANG Li. Experimental Observation of Thickener Effects on Grease Film Evolution[J]. Journal of Mechanical Engineering, 2025, 61(21): 318-328.

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