• Tribology and Lubricants
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• v.19 no.5
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• pp.280-284
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• 2003

High performance characteristics are required for rolling bearings and the various functions of bearing are greatly influenced by grease. Recently, higher performance is being demanded of rolling bearing greases for bearing lubrication. Four special greases with different composition such as lithium soap/ester oil, urea/ester oil, urea/ether oil and PTFE/fluorine oil were synthesized to compare the performance of these greases with that of the conventional lithium soap/mineral oil grease. The grease properties were investigated using a series of typical grease testing methods and grease life test. After the life test, the greases were charaterized by FTIR analysis and a microscope. And the iron amount in the greases was analyzed by AAS after ashing. The composition and manufacturing process determined the grease performance. The grease with a base oil of synthetic oil showed higher performance and the urea/ester oil and PTFE/fluorine oil showed about three times longer life as compared with conventional lithium grease.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.179-185
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• 2001

High performance characteristics are required for rolling bearings and the various functions of bearing are greatly influenced by grease. Recently, higher performance is being demanded of rolling bearing greases for bearing lubrication. Four special greases with different composition such as lithium soap/ester oil, urea/ester oil, urea/ether oil and PTFE/fluorine oil were synthesized to compare the performance of these greases with that of the conventional lithium soap/mineral oil grease. The grease properties were investigated using a series of typical grease testing methods and grease life test. After the life test, the greases were charaterized by FTIR analysis and a microscope. And the iron amount in the greases was analyzed by AAS after ashing. The composition and manufacturing process determined the grease performance. The grease with a base oil of synthetic oil showed higher performance and the urea/ester oil and PTFE/fluorine oil showed about three times longer life as compared with conventional lithium grease.

• Tribology and Lubricants
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• v.22 no.5
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• pp.269-275
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• 2006

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve bearing lubrication. Three urea/ether oil greases with different composition were synthesized to compare the performance of these greases. The typical grease physical properties were investigated, and life test of these greases was conducted by FE-9 grease life tester. The grease with higher content of the thickener showed higher performance. After these preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT value. And optimized conditions for grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT value respectively. The optimized grease using OIT value showed longer grease life than that using dropping point. Two greases were synthesized following the optimum synthesis conditions by means of OIT value. Then grease life and other properties of these greases were investigated. These two greasaes showed longer grease life than typical urea/ether oil grease.

• Tribology and Lubricants
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• v.37 no.1
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• pp.7-13
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• 2021

Ball bearing is a device that supports and transmits a load acting on a rotating shaft, and it is a type of rolling bearings that uses the rolling friction of the balls by inserting balls between the inner ring and the outer ring. Grease, which is prepared by mixing a thickener with a base oil, is a lubricant commonly used in bearings and has the advantage of a simple structure and easy handling. Bearings are increasingly being used in high value-added products such as semiconductors, aviation, and robots in the era of the 4th industrial revolution. Accordingly, there is an increasing demand for bearing grease. The selection of grease is an important factor in the bearing design. Therefore, a study must be conducted on the grease life evaluation to select an appropriate grease according to operating conditions such as a high temperature, high rotational speed, and high load. In this study, we evaluate the life of ball-bearing grease according to various operating conditions, namely, temperature, speed, and load changes. For this, we develop and theoretically verify a grease life test machine for ball bearings. We conduct a life test of grease according to various operating conditions of bearings and predict the grease life with a 10% and 50% failure probability using the Weibull analysis. In addition, we analyze the oxide characteristics of the grease over time using the Fourier transform infrared spectroscopy and the deterioration characteristics of the grease using the carbonyl index.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.129-138
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• 2003

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required in improve bearing lubrication. Three urea/ether oil greases with identical composition were synthesized to compare the performance of these greases according to the thickener content of grease. The typical grease physical properties were investigated. And life test of these greases was conducted by FE-9 grease life tester. The characteristics of the greases before and after life test were investigated using FT-IR, microscope, OIT and TAN meter. Large differences in the grease performance depending on the content of the thickener were observed. The grease with higher content of the hickener showed higher performance such as long life time and low TAN value. After preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT, then optimized two greases were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT data. Characteristics of the optimized two greases were on the same level with estimated value. The optimized grease by means of OIT value showed longer grease life in comparison with optimized grease by dropping point. However two greases showed higher performance than typical urea/ether oil.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.123-129
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• 2004

Rolling bearings are assorted one of the most important machine elements. The various functions of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve rolling bearing lubrication. The two conditions for optimum grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) program by using dropping points and OIT values respectively. And the optimized two urea/ether oil greases were synthesized to compare the performance. The typical physical properties of grease were investigated. And life test of these greases was conducted by rolling bearing grease life tester The characteristics of the greases before and after life test were investigated using FTIR, microscope, SEM, TG/DSC, OIT and TAN meter The optimized two greases showed longer life time than typical urea/ether oil grease. The optimized grease by means of OIT value showed higher performance such as long life time. low TAN value and high oil bleeding amount in comparison with the optimized grease using dropping point.

• Tribology and Lubricants
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• v.21 no.1
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• pp.21-26
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• 2005

Rolling bearings are assorted one of the most important machine elements. The various functions of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve rolling bearing lubrication. The two conditions for optimum grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) program by using dropping points and OIT values respectively. And the optimized two urea/ether oil greases were synthesized to compare the performance. The typical physical properties of grease were investigated. And life test of these greases was conducted by rolling bearing grease life tester. The characteristics of the greases before and after life test were investigated using FTIR, microscope, SEM, TG/DSC, OIT and TAN meter. The optimized two greases showed longer life time than typical urea/ether oil grease. The optimized grease by means of OIT value showed higher performance such as long life time, low TAN value and high oil bleeding amount in comparison with the optimized grease using dropping point.

• Tribology and Lubricants
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• v.18 no.4
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• pp.273-278
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• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.111-116
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• 2004

Li-complex and urea type greases (each 10 species) which were furnished by Chang-Am LS, analyzed anti-wear performance into fretting wear tester & four-bail wear tester. from the results of fretting wear test, the wear volume of Li-complex greases are $4.6\~8.9mg\;and\;8.3\~14.4mg$ with the test of urea greases. The anti-wear performance for 4-ball wear test of greases produced results around 0.5mm at the value of WSD. The grease life performance were evaluated by SKF-ROF Grease Tester and wheel bearing life tester. From the results of SKF-ROF tester, the life performance evaluated by whole working time produced results $50\~300hr$ with the Li-complex greases and 100-1000hr with the urea greases. That is to say, in spite of severe condition at the higher of $10^{\circ}C$ reaction temp, the life performance with Urea type greases are much superior to Li-complex type greases. Prior to wheel bearing life tester, the grease selected performance evaluation(=anti-wear test) are tested by wheel bearing tester. In this results, we can confirm results those are similar with SKF-ROF tester. In this study, we can draw two major conclusions, one is that Li-complex greases are superior to urea greases with anti-wear properties and the other is that urea greases are much superior to Li-complex greases with life performance.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1239-1246
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• 2022

This paper introduces the effect of grease on the degradation characteristics of bearings used as key components of packaging equipment and automation systems. Bearings parts are installed to fix and support the rotating body of the system, and performance degradation of the bearings has a great effect on the life of the system too. When bearings are used in various devices and systems, the grease is applied to reduce friction and improve fatigue life. Determining the type of lubricant (grease) is important because it has a great influence on the operating environment and lifespan and ensures long lifespan of systems and facilities. However, studies that simultaneously compared and analyzed the change in mechanical degradation characteristics and the comparison of chemical degradation characteristics according to grease types under actual operating conditions are insufficient. In this paper, three types of small harmonic drive, high-load reducer, and low-load reducer grease used in power transmission joint modules are experimentally selected and finally injected into ball bearings with a load (19,500N) to improve bearing durability. Degradation characteristics were tested by attaching to test equipment. At this time, after the durability test under the same load conditions, the mechanical degradation characteristics, that is temperature, vibration according to the three greases types. In addition, the chemical degradation characteristics of the corresponding grease was compared to present the results of mutual correlation analysis.