scholarly journals Loss evaluation of gear pair by grease lubrication for small-sized geared motor (Influence on cone penetration, kinematic viscosity and kind of base oil of grease)

2014 ◽  
Vol 80 (817) ◽  
pp. DSM0277-DSM0277
Author(s):  
Yoichi MATSUMOTO ◽  
Haruo HOUJOH
Keyword(s):  
Kinematic Viscosity ◽  
Gear Pair ◽  
Cone Penetration ◽  
Grease Lubrication ◽  
Base Oil

Influence of Grease Characteristics on Gear Friction Loss

2015 ◽  
Author(s):  
Yoichi Matsumoto ◽  
Haruo Houjoh
Keyword(s):  
Friction Coefficient ◽  
Kinematic Viscosity ◽  
Friction Loss ◽  
Cone Penetration ◽  
Base Oil ◽  
Aluminum Complex ◽  
Gear Teeth ◽  
Gear Mesh ◽  
Lithium Soap ◽  
Mineral Base

In a previous study, we analyzed the mechanical loss factors of a small-sized geared motor comprising an induction motor and a parallel gear reducer. The load dependent loss is mainly caused by gear mesh friction, which is related to grease characteristics. This study investigates how the grease characteristics influence the friction loss of the gear mesh. The important grease characteristics are the cone penetration, kinematic viscosity, type of base oil, and type of thickener. The loss of gear mesh friction was evaluated in terms of the average friction coefficient between the gear teeth and was found to be unrelated to the cone penetration and kinematic viscosity of the base oil. The average friction coefficient of grease combined with lithium soap/poly urea and mineral base oil was 0.09–0.11; when combined with aluminum complex soap and synthetic base oil, the friction coefficient reduced to 0.07–0.08.

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.

scholarly journals Scoring in Spur Gear Pair : 1st Report, Scoring Temperature in Case of Gear Base Oil

1986 ◽  
Vol 29 (255) ◽  
pp. 3174-3181
Author(s):  
Fumio OBATA ◽  
Komei FUJITA ◽  
Masahiro FUJII ◽  
Kosei MATSUO
Keyword(s):  
Spur Gear ◽  
Gear Pair ◽  
Base Oil

scholarly journals Optimization of the Rheological Properties and Tribological Performance of SAE 5w-30 Base Oil with Added MWCNTs

Lubricants ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 94
Author(s):  
Bahaa M. Kamel ◽  
Vineet Tirth ◽  
Ali Algahtani ◽  
Mohamed S. Shiba ◽  
Ahmed Mobasher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Rheological Properties ◽  
Kinematic Viscosity ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Wear Scar Diameter ◽  
Multiwalled Carbon ◽  
Base Oil ◽  
Weight Percentage ◽  
Lubricant Oil

The augmentation of lubricant oil properties is key to protecting engines, bearings, and machine parts from damage due to friction and wear and minimizing energy lost in countering friction. The tribological and rheological properties of the lubricants are of utmost importance to prevent wear under unembellished conditions. The marginal addition of particulate and filamentous nanofillers enhances these properties, making the lubricant oil stable under severe operating conditions. This research explores the improvement in SAE 5w-30 base oil performance after the addition of multiwalled carbon nanotubes (MWCNTs) in six marginal compositions, namely, Base, 0.02, 0.04, 0.06, 0.08, and 0.10 weight percentage. The effect of the addition of MWCNTs on flash and pour points, thermal conductivity, kinematic viscosity, friction coefficients, and wear are investigated and reported. X-ray diffraction and transmission electron microscopy are used to characterize the MWCNTs. The purity, crystallinity, size, shape, and orientation of the MWCNTs are confirmed by XRD and TEM characterization. Pour points and flash points increase by adding MWCNTs but inconsistency is observed after the 0.06 wt.% composition. The thermal conductivity and kinematic viscosity increase significantly and consistently. The friction coefficient and wear scar diameter reduce to 0.06 wt.% MWCNTs and then the trend is reversed due to agglomeration and inhomogeneity. A composition of 0.06 wt.% is identified as the optimum considering all the investigated properties. This composition ensures the stability of the tribo-film and hydrodynamic lubrication.

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.

Thermal oxidation behavior of trimethylolpropane trioleate base oil when exposed to iron surfaces

2019 ◽  
Vol 72 (3) ◽  
pp. 473-478
Author(s):  
Yongliang Jin ◽  
Jian Li ◽  
Bingxue Cheng ◽  
Dan Jia ◽  
Jiesong Tu ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Thermal Oxidation ◽  
Kinematic Viscosity ◽  
Oxidation Behavior ◽  
Interaction Mechanism ◽  
Acid Value ◽  
Time Intervals ◽  
Bulk Oil ◽  
Content Type ◽  
Base Oil

Purpose This paper aims to investigate the thermal oxidation behavior of trimethylolpropane trioleate (TMPTO) base oil when exposed to Fe surfaces. Design/methodology/approach Samples of TMPTO bulk oil were placed in Fe vessels and heated in an oven to accelerate the oxidation at different time intervals, while others were placed in glass vessels and used as experimental controls. Subsequently, the physicochemical properties of the oxidized TMPTOs, including the kinematic viscosity and acid value, were measured and a structural analysis was conducted using the Raman and Fourier transform infrared (FTIR) techniques. Findings The results demonstrate that the TMPTO bulk oil exhibited an exponential increase in the kinematic viscosity along with the increasing acid value over the oxidation time. The Fe surface significantly increased the kinematic viscosity of TMPTO, while only mildly impacting its acid value compared with the experimental controls. The structural analysis results of the TMPTO suggest that the C = C and = C-H bonds were the vulnerable sites. Furthermore, the results suggest that the Fe surface evidently accelerates the chemical reactions of the C = C and the = C-H bonds, and less alcohols and more carbonyl products were identified in the oil samples that were heated in the Fe vessels. Originality/value The results demonstrate that the Fe surfaces affected the oxidation behavior of the TMPTO base oil, and an interaction mechanism between the Fe and the TMPTO is developed.

Influence of temperature on wear performance of greases in rolling bearings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Laura Rosenkranz ◽  
Silvia Richter ◽  
Georg Jacobs ◽  
Adrian Mikitisin ◽  
Joachim Mayer ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Roller Bearing ◽  
Operating Parameter ◽  
Rolling Bearing ◽  
Grease Lubrication ◽  
Content Type ◽  
Base Oil ◽  
Impact Pathways ◽  
Wear Protection ◽  
Lubrication Conditions

Purpose Rolling bearing operation under mixed and boundary lubrication conditions may lead to heavy adhesive or abrasive wear, which may lead to wear-induced rolling bearing failure. The purpose of this paper is to investigate the wear protection capabilities of different grease compositions at varying temperatures. It is considered that the temperature influences the lubrication conditions, the behaviour of grease components, namely, bleed oil and thickener, as well as the tribofilm formation due to tribo-chemical interactions between additives and surfaces. Design/methodology/approach In this study, four different greases were produced on the basis of a mineral base oil by varying the thickener and the addition of ZDDP. Various grease-lubricated rolling bearing experiments were conducted in a wide temperature range from 0°C to 120°C. Subsequently, the wear pattern, tribofilm formation and grease structures were analysed. Thereby, the influence of the different grease thickeners and the performance of ZDDP as a common antiwear and extreme pressure additive was evaluated. Findings The results show a strong temperature-dependency and allow a classification of temperature ranges concerning wear protection. At low temperatures, all greases provide a very good wear protection without the evidence of additive-based tribofilm formation. In the experiments at elevated temperatures, ZDDP tribofilms were formed. The formation depends on the thickener type: in comparison to lithium thickener, polyurea thickener favours more protective tribofilms at the same temperature. The experimental results show that medium temperatures in the range of 40°C–60°C are critical concerning wear due to the insufficient tribolayer formation and limited load carrying capacity of the grease. Originality/value Temperature is a key operating parameter for grease lubrication in roller bearings. The experimental work enables consideration of different impact pathways of temperature by combining roller bearing tests and microanalysis.

Grease Performance in Tapered Roller Bearings

2005 ◽  
Author(s):  
Michael R. Hoeprich
Keyword(s):  
Sem Analysis ◽  
Rolling Element Bearing ◽  
Oil Viscosity ◽  
Grease Lubrication ◽  
Base Oil ◽  
Rolling Element ◽  
Post Test ◽  
Tapered Roller ◽  
Element Bearing ◽  
Tapered Roller Bearings

To gain insight into the physical aspects of grease lubrication, nine greases with different oil viscosity and thickener combinations were tested in a tapered rolling element bearing under a light thrust load at speeds of 1800 and 3600 RPM. Bearings were run for thirty days or until a 150°C rib temperature was reached. Using SEM analysis, thickener samples were taken after testing from the rib/roller and raceway contacts for comparison with the thickener in new grease. A post test infrared technique was also used to evaluate grease thickness at the rib/roller contact and was compared with calculated film thickness. Bearing operating temperatures were then compared with grease base oil viscosity and thickener type.

scholarly journals Effect of Over Rolling Frequency on the Film Formation in Grease Lubricated EHD Contacts under Starved Conditions

Lubricants ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 19 ◽  
Author(s):  
Dennis Fischer ◽  
Helko Mues ◽  
Georg Jacobs ◽  
Andreas Stratmann
Keyword(s):  
Film Thickness ◽  
Film Formation ◽  
Angular Distance ◽  
Grease Lubrication ◽  
Base Oil ◽  
Lubricated Contacts ◽  
Lubricating Film ◽  
Rolling Element ◽  
Operating Lifetime ◽  
Future Work

The service life of rolling bearings is significantly affected by the lubricating film formation in elastohydrodynamic (EHD) contacts. Grease lubricated EHD contacts show a film thickness decay from a characteristic rotational speed, which is referred to as starvation. Thus, the film thickness of grease lubricated contacts differs from that of oil lubricated contacts. However, the base oil properties under fully flooded conditions are commonly assumed to estimate the operating lifetime of grease lubricated bearings, which are usually not fully flooded. Hence, this assumption results in an overestimation of the film thickness for rotational speeds in the range of starvation, which can lead to uncertainties in the bearing design. At high rotational speeds, i.e., high over rolling frequencies, starvation is likely to occur, due to insufficient lubricant supply by replenishment behind the rolling element. Therefore, the focus of this contribution is to investigate the effect of over rolling frequency, and thus replenishment time, on the lubricating film formation in starved, grease lubricated EHD contacts. The film thickness measurements were performed on a ball-on-disc tribometer, which was extended by adding a second ball specimen in front of the measuring ball. By varying the angular distance between the two contacts, the lubricant displacement can be controlled, such that the effect of replenishment time on the film formation can be determined. These investigations should help to establish an advanced understanding of the mechanisms of grease lubrication, and encourage future work with a focus on developing a method to predict the film formation in grease lubricated EHD contacts.

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