• Tribology and Lubricants
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• v.16 no.3
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• pp.182-187
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• 2000

In this paper the residual stresses on lubricated sliding surfaces were measured during break-in procedure and up to scuffing by the X-ray diffraction method. The cylinder-on-disk type tribometer was used with the line-contact geometry. Scuffing tests were done using a constant load. In the break-in procedure the loads were increased from very low values in several steps. It was found that the sliding surfaces with break-in represented relatively higher values of residual compressive stresser than those without break-in. The residual stresses below the surfaces showed the small amount of stress increases. The results of scuffing tests with and without break-in showed the same trends as break-in tests did. However, in case of tests with break-in procedure the stresses below the surfaces showed very large increases in the residual compressive stresses. From the tests of break-in and scuffing, it was found that the increases in scuffing lives were related with the increases of residual stresses on the lubricated sliding surfaces with break-in.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.34-39
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• 2002

The surfaces of machine components in sliding contact such as bearing, gears and pistons etc. frequently operate under the condition of mixed lubrication due to high load, high speed and slip. These machine components often undergo the inception of scuffing in practical application. The scuffing failure is a critical problem in modern machine components, especially for the requirement of high efficiency and small size. However, it is difficult to find a universal mechanism to explain all scuffing phenomena because there are so many factors affecting the onset of scuffing. In this study, scuffing experiments are conducted using Acoustic Emission(AE) measurement by an indirect sensing approach to detect scuffing failure. Acoustic Emission(AE) signal has been widely utilized to monitor the interaction at the friction interface. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers eon the contacting surfaces in real time. The FFT(Fast Fourier Transform)analyses of the AE signal are used to understand the interfacial interaction and the relationship between the AE signal and the state of contact is presented

• Tribology and Lubricants
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• v.18 no.5
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• pp.351-356
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• 2002

The surfaces of machine components in sliding contact such as bearing, gears and pistons etc. frequently operate under the condition of mixed lubrication due to high load, high speed and slip. These machine components often undergo the inception of scuffing in practical application. The scuffing failure is a critical problem in modern machine components, especially for the requirement of high efficiency and small size. However, it is difficult to find a universal mechanism to explain all scuffing phenomena because there are so many factors affecting the onset of scuffing. In this study, scuffing experiments are conducted using Acoustic Emission(AE) measurement by an indirect sensing approach to detect scuffing failure. Acoustic Emission(AE) signal has been widely utilized to monitor the interaction at the friction interface. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time. The FFT(Fast Fourier Transform) analyses of the AE signal are sued to understand the interfacial interaction and the relationship between the AE signal and the state of contact is presented.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.159-165
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• 2000

In this paper the residual stresses on lubricated sliding surfaces were measured during break-in procedure and up to scuffing by the X-ray diffraction method. The cylinder-on-disk type tribometer was used with the line-contact geometry. Scuffing tests were done using a constant load. In the break-in procedure the loads were increased from very low values in several steps. It was found that the sliding surfaces with break-in represented relatively higher values of residual compressive stresses than those without break-in. The residual stresses below the surfaces showed the small amount of stress increases. The results of scuffing tests with and without break-in showed the same trends as break-in tests did. However, in case of tests with break-in procedure the stresses below the surfaces showed very large increases in the residual compressive stresses. From the tests of break-in and scuffing, it was found that the increases in scuffing lives were related with the increases of residual stresses on the lubricated sliding surfaces with break-in.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.415-416
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• 2002

Experiments have been conducted to investigate scuffing mechanism in oil lubricated piston-ring /cylinder sliding contacts. Samples were extracted from actual components to simulate the real contact geometry and other influencing conditions. A standard test machine. with some modifications, has been used for the investigation of the effects of surface temperature load and sliding velocity. preliminary tests were carried out to find the critical temperature of scuffing using gradient temperature under a constant load, reciprocating frequency and stroke. The experimental and analytical results show that a transition from lubricated contact to adhesion, accompanied by the phenomena such as material transfer between the two sliding surfaces, local contact welding and temperature rise, and sharp increase in friction coefficient, appears to contribute to the final failure of scuffing.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.191-192
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• 2002

The scuffing failure is a critical problem in modern machine components, especially for the requirement of high efficiency and small size. In this study. scuffing experiments are conducted using Acoustic Emission(AE) measurement by an indirect sensing approach to detect scuffing failure. Using AE signals we con get and indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surface in real time. The FFT(Fast Fourier Transform)analyses of the AE signal are used to understand the interfacial interaction and the relationship between the AE signal and the state of contact is presented.

• Tribology and Lubricants
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• v.14 no.4
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• pp.7-14
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• 1998

A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain increment in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain increments. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain increment shows 0.0062, and in the mineral oils and commercial engine oils in air, plastic strain increments show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing-failure life.

• Tribology and Lubricants
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• v.18 no.3
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• pp.211-218
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• 2002

The effect of characteristic of surface roughness and roughness patterns on friction was studied experimentally in boundary lubrication with reciprocating tribometer. Roughness was changed from Ra=0.2($\mu\textrm{m}$)to Ra=1.2($\mu\textrm{m}$). Three roughness pattern-transverse, oblique, longitudinal- were tested for various load and velocity. The experimental results show that the scuffing resistance of surfaces with transversal roughness pattern is higher than that of surface with longitudinal and obliq pattern. under the conditions of the roughness values of Ra=0.2, 0.5,1.0 and 1.2. surfacer roughness (Ra) was decreased with the normal load increased before scuffing occurred. oblique pattern and longitudinal pattern with Ra=0.2 and Ra=1.0 was higher scuffing load under low sliding velocity, but with Ra=0.5 was higher scuffing load under high sliding velocity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.91-99
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• 1998

A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain shows 0.0062, and In the mineral oils and commercial engine oils in air, plastic strain show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing life.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.64-71
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• 2001

In this paper the ball-on-disk type sliding tests with boundary lubricated steels were carried out to verify the relation between surface profiles and wear as well as scuffing. Three kinds of surface roughness and asperity radius were produced on AISI 1045 steels using the different processes of grinding and polishing. Frictional forces and time to scuffing were measured. Also, the shape and amount of wear particles were analyzed to compare with original profiles. From the tests, it was confirmed that the size of wear particles are very related to original surface profile. The time to failures and wear amounts were sensitive to the surface spacing. The large surface spacing shows much longer sliding life and smaller wear amount than the others. Time to scuffing was increased with increasing surface profile spacing. The size of wear particles was increased and the amount was decreased with increasing surface profile spacing. Wear volume and wear rate K were decreased with increasing surface profile spacing. And after sliding tests, surface cracks of inner parts of the wear track occurred scuffing were observed and compared the differences about each specimen having the different surface profile spacing.