The Relative Thickness of Grease and Oil Films in Rolling Bearings

1979 ◽  
Vol 193 (1) ◽  
pp. 185-192 ◽  
Author(s):  
A. R. Wilson
Keyword(s):  
Viscous Friction ◽  
Relative Thickness ◽  
Grease Lubrication ◽  
Rolling Bearings ◽  
Base Oil ◽  
Oil Films

A method for measuring the thickness of grease films between the rollers and rings of rolling bearings is described. Measurements in two designs of bearing show that a grease can initially form thicker films than can its base oil but that, without frequent relubrication, the grease films become slightly the thinner with time. The thinning of grease films, which is attributed to partial starvation, is accompanied by a reduction in viscous friction. Except in critical applications, where the thickest films are required, the consequences of partial starvation associated with grease lubrication can be advantageous.

scholarly journals Cavitation Growth Phenomena in Pure-Sliding Grease EHD Contacts

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 75
Author(s):  
Takefumi Otsu ◽  
Romeo Glovnea ◽  
Joichi Sugimura
Keyword(s):  
High Speed ◽  
Cavity Growth ◽  
Growth Time ◽  
In Situ Observation ◽  
Oil Viscosity ◽  
Grease Lubrication ◽  
Base Oil ◽  
Lubrication Film ◽  
Initial Stage ◽  
Cavity Growth Rate

This article describes experimental and theoretical studies on the cavitation phenomena in the grease lubrication film under pure sliding elastohydrodynamic contact. In situ observation tests using the optical interferometry technique were conducted, and the growth of cavitation was captured using a high-speed camera. The results showed that the cavity grew in two stages, which was similar to the behavior in the base oil, and that the cavity growth rate in the initial stage was higher than that in the second stage. In the initial stage, the cavity growth time in the grease was longer than that in the base oil, and the cavity length after the growth depended on the base oil viscosity. It was also found in the test using diurea grease that small cavities were formed by the lumps of thickener. The cavity growth in the initial stage was discussed by numerical simulation of pressure distribution based on a simple rheological model.

Effects of Grease Types on Vibration and Acoustic Emission of Defective Linear-Guideway Type Recirculating Ball Bearings

2010 ◽  
Author(s):  
Hiroyuki Ohta ◽  
Shinya Hayashi ◽  
Soichiro Kato ◽  
Yutaka Igarashi
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Experimental Results ◽  
Ball Bearings ◽  
Oil Viscosity ◽  
Grease Lubrication ◽  
Base Oil ◽  
Defect Angle

In this paper, vibrations and acoustic emissions (AEs) of defective linear-guideway type recirculating ball bearings under grease lubrication were measured. The experimental results show that the vibration and AE amplitudes (the pulse amplitudes, the RMS values) of both the normal and defective bearings have a tendency to be reduced when a grease with higher base oil viscosity is used. Under the same type of grease, the RMS values of the vibrations and AE of the defective bearings increase as the defect angle increases. However, the increases of the RMS values due to increased defect angle are reduced when a grease with higher base oil viscosity is used.

On the Chaotic Behavior of Grease Lubrication in Rolling Bearings

2009 ◽  
Vol 52 (5) ◽  
pp. 581-590 ◽  
Author(s):  
PIET M. LUGT ◽  
SLAVCO VELICKOV ◽  
JOHN H. TRIPP
Keyword(s):  
Chaotic Behavior ◽  
Grease Lubrication ◽  
Rolling Bearings

scholarly journals Investigation of Tribological Behavior of Lubricating Greases Composed of Different Bio-Based Polymer Thickeners

Lubricants ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 80
Author(s):  
Seyedmohammad Vafaei ◽  
Dennis Fischer ◽  
Max Jopen ◽  
Georg Jacobs ◽  
Florian König ◽  
...  
Keyword(s):  
Film Thickness ◽  
Renewable Resources ◽  
Tribological Behavior ◽  
Renewable Materials ◽  
Friction Behavior ◽  
Rolling Bearings ◽  
Base Oil ◽  
Tribological Tests ◽  
Lubrication Properties ◽  
Ball On Disc

One commonly used lubricant in rolling bearings is grease, which consists of base oil, thickener and small amounts of additives. Commercial greases are mostly produced from petrochemical base oil and thickener. Recently, the development of base oils from renewable resources have been significantly focused on in the lubricant industry. However, to produce an entirely bio-based grease, the thickener must also be produced from renewable materials. Therefore, this work presents the design and evaluation of three different bio-based polymer thickener systems. Tribological tests are performed to characterize lubrication properties of developed bio-based greases. The effect of thickener type on film thickness and friction behavior of the produced bio-based greases is evaluated on a ball-on-disc tribometer. Moreover, the results are compared to a commercial petrochemical grease chosen as benchmark.

Correlation of base oil viscosity in grease with vibration severity of damaged rolling bearings

2018 ◽  
Vol 70 (2) ◽  
pp. 264-272 ◽  
Author(s):  
Imran Moulaalli Jamadar ◽  
Dipakkumar Vakharia
Keyword(s):  
Theoretical Model ◽  
Design Methodology ◽  
Oil Viscosity ◽  
Rolling Bearings ◽  
Content Type ◽  
Base Oil ◽  
Lubricant Oil ◽  
Bearing Failures ◽  
Different Types ◽  
Lubrication Condition

Purpose The main objective of the paper is to explore the theoretical correlation of base oil viscosity in grease and to study the effect of grease grade on mechanical vibrations associated with the damaged rolling bearings. Design/methodology/approach For theoretical purposes, formulation theory of dimensional analysis was implemented. Experiments were then performed on the test bearings lubricated with three different types of greases, namely, SKF LGHP2, SKF LGMT3 and SKF LGWA2. Findings The numerical results obtained from the theoretical model along with the results of experiments show that the vibration amplitudes of the defective bearings come down to a lower level when it is lubricated with the grease of a higher base oil viscosity. Research limitations/implications The promising results from the theoretical model make it usable for the practical rotating machineries applying a variety of the rolling bearings. Consequently, if the bearing is not severely damaged, its performance can be increased by lubricating it with thicker grease. Originality/value Despite many significant contributions in the field to detect the presence of defects, not many studies have been performed that relate the lubrication condition of the rolling bearings with the vibration response, because around 50-75% of the bearing failures are attributed to be lubrication related. Hence, there is need to develop a mathematical model that can correlate the vibration severity of the bearings with viscosity of the lubricant oil in the greases along with other design and operating parameters.

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