Vibration and Acoustic Emission Measurements Evaluating the Separation of the Balls and Raceways With Lubricating Film in a Linear Bearing Under Grease Lubrication

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Hiroyuki Ohta ◽  
Yuko Nakajima ◽  
Soichiro Kato ◽  
Hideyuki Tajimi
Keyword(s):  
Acoustic Emission ◽  
Ball Bearing ◽  
Linear Velocity ◽  
Oil Viscosity ◽  
Grease Lubrication ◽  
Base Oil ◽  
Lubricating Film ◽  
Contact Voltage ◽  
Film Parameter ◽  
Vibratory Acceleration

This paper deals with vibration and acoustic emission (AE) measurements evaluating the separation of the balls and raceways with lubricating film in a linear-guideway–type recirculating ball bearing (linear bearing) under grease lubrication. In the experiments, three types of commercial grease, AS2, LG2, and PS2, were used. The vibratory acceleration, AE, temperature, and electric conductivity (contact voltage) in the test bearing were measured, while a carriage of the test bearing was driven at a certain linear velocity. Experimental results showed that the measured vibratory acceleration, AE, and contact voltage of the test bearing were affected by the linear velocity and the base oil viscosity of the grease. Next, the rail side film parameter ΛR and the carriage side film parameter ΛC were examined for the test bearing in operation, and it was shown that the ΛR value was lower than the ΛC value. In addition, a condition for the separation of all the balls and raceways with lubricating film was presented. Finally, it was shown that the measured root-mean-square (RMS) values of vibratory acceleration or AE can be used for evaluating the separation of all the balls and raceways with lubricating film in the test bearing.

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.

Effects of Grease Characteristics on Sound and Vibration of a Linear-Guideway Type Recirculating Ball Bearing

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Hiroyuki Ohta ◽  
Tatsuya Tsuruoka ◽  
Yukitoshi Fujinami ◽  
Soichiro Kato
Keyword(s):  
Atmospheric Pressure ◽  
Sound Pressure ◽  
Ball Bearing ◽  
Viscosity Coefficient ◽  
Linear Velocity ◽  
Base Oil ◽  
First Sound ◽  
Absolute Viscosity ◽  
Vibratory Acceleration ◽  
Sound Vibration

This paper deals with the effects of grease characteristics on sound and vibration of a linear-guideway type ball bearing. First, sound, vibration, and temperature of a linear-guideway type ball bearing were measured by changing 16 types of greases. Next, in order to explain the effects of grease characteristics (absolute viscosity η0 of the base oil in the grease at atmospheric pressure, pressure–viscosity coefficient ξ of the base oil, and penetration P of grease) and linear velocity V on the sound pressure p and vibratory acceleration a of the linear bearing, dimensional analyses were carried out. The dimensional analyses derived dimensionless products Pp/(η0V) and η0ξV/P for the sound, and dimensionless products Pa/V2 and η0ξV/P for the vibration. The plot of the measured data using dimensionless products showed that both sound pressure p and vibratory acceleration a (under a certain linear velocity) decreased as the absolute viscosity η0 of the base oil in the grease at atmospheric pressure or the pressure–viscosity coefficient ξ increased. Whereas the sound pressure p decreased as the penetration P decreased, the vibratory acceleration a decreased as P increased.

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.

Friction Forces in a Linear-Guideway Type Recirculating Ball Bearing Under Grease Lubrication

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Hiroyuki Ohta ◽  
Kazunori Oguma ◽  
Koji Takane ◽  
Soichiro Kato
Keyword(s):  
Friction Force ◽  
Ball Bearing ◽  
Internal Space ◽  
Filling Rate ◽  
Grease Lubrication ◽  
Friction Forces ◽  
Contact Voltage ◽  
Measured Time ◽  
Time Average ◽  
Differential Slip

Abstract This paper deals with friction forces in a linear-guideway type recirculating ball bearing (linear bearing) under grease lubrication. During the experiments, the friction force, temperature, and electric contact voltage of a grease lubricated linear bearing (test bearing) without seals were measured. Experimental results showed that the measured friction forces of the test bearing were fluctuated with the ball passage period. The measured time-average friction force FAVG (measured FAVG) was nearly constant when the grease filling rate x (=grease filling volume/internal space of the bearing) ≥0.13, while the measured FAVG decreased as x decreased when x < 0.13. In addition, the measured temperatures were almost constant, and the measured contact voltages indicated that the contacts of the balls and raceways were electrically insulated by the grease film. Next, the expressions of friction forces due to differential slip (FD), elastic hysteresis loss (FE), and rolling traction (FRT) were shown. The calculated FD + FE + FRT for the test bearing was almost equal to the measured FAVG around the grease filling rate of x = 0, while in cases where x > 0, the measured FAVG was greater than the calculated FD + FE + FRT. This means that when x > 0, an agitating resistance (FA) from the grease might cause the measured FAVG to be greater than the calculated FD + FE + FRT. Finally, an expression for the friction force of a linear bearing, FAVG = FD + FE + FRT + FA (which can estimate the measured ones) is proposed.

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.

scholarly journals Optical Analysis of Ball Bearing Starvation

1971 ◽  
Vol 93 (3) ◽  
pp. 349-361 ◽  
Author(s):  
L. D. Wedeven ◽  
D. Evans ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Ball Bearing ◽  
Point Contact ◽  
Experimental Measurements ◽  
Line Contact ◽  
Optical Analysis ◽  
Grease Lubrication ◽  
Theoretical Predictions ◽  
Pressure Stress ◽  
Starvation Conditions

Elastohydrodynamic oil film measurements for rolling point contact under starvation conditions are obtained using optical interferometry. The experimental measurements present a reasonably clear picture of the starvation phenomenon and are shown to agree with theoretical predictions. Starvation inhibits the generation of pressure and, therefore, reduces film thickness. It also causes the overall pressure, stress, and elastic deformation to become more Hertzian. Additional experiments using interferometry illustrate: the cavitation pattern, lubricant entrapment, grease lubrication, ball spin, and edge effects in line contact.

Synergistic Antiwear Effects of Zinc Dialkyl Dithiophosphate and Different Detergents

2008 ◽  
Author(s):  
G. Pennecot ◽  
K. Komvopoulos ◽  
E. S. Yamaguchi
Keyword(s):  
Wear Rate ◽  
Boundary Lubrication ◽  
Base Oil ◽  
Temperature Range ◽  
Zinc Dialkyl Dithiophosphate ◽  
Contact Voltage ◽  
Lubrication Regime ◽  
Steel Surfaces ◽  
Dialkyl Dithiophosphate ◽  
Insight Into

The effectiveness of blends consisting of base oil, some secondary zinc dialkyl dithiophosphate (ZDDP), and different detergents to form antiwear tribofilms on steel surfaces sliding in the boundary lubrication regime was investigated in the temperature range of 105–125°C. The efficacy of the tribofilms formed from these blends was evaluated in terms of contact voltage and wear rate measurements. The best antiwear performance was demonstrated by the tribofilm formed from the blend containing sulphonate detergent. The results of this study provide insight into competing effects between ZDDP and different detergents that affect significantly the antiwear performance of the formed tribofilms.

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