Running-In and the Enhancement of Scuffing Resistance

Kelly, D A; Barnes, Christopher; Freeman, Ralph; Critchlow, Gary W.

doi:10.1243/pime_proc_1992_206_150_02

Cited by 15 publications

(4 citation statements)

References 7 publications

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“…Twin-disc tests under conditions of microelastohydrodynamic lubrication confirmed that prior run-in at a lower sliding speed as opposed to a higher speed enhances the scuffing resistance at more severe loads and temperatures (5). Examination of surface oxidation and smoothing provided the insight that the latter is the dominant result.…”

Section: Introductionmentioning

confidence: 82%

Tribological effects of roughness and running-in on oil-lubricated line contacts

Chou

Lin

1997

Proceedings of the Institution of Mechanical Engineers, Part J:

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A gear=cam adapter was employed to study various aspects of line-contact lubrication, using oil with extreme-pressure additive at two different concentrations. The effect of run-in on the tribological performance of rollers with two different surface roughnesses was investigated in terms of friction coefficient, wear loss, oil temperature, specimen roughness and electrical resistance. The relation between roller wear loss and the time rate of electrical resistance change was established. Electrical resistance versus oil temperature underwent a dramatic change during testing, a period of rising oil temperature and relatively constant low electrical resistance abruptly becoming a period of relatively constant oil temperature and rising electrical resistance, low wear rates correlating strongly with the second period. The run-in effect on roller wear loss in smooth rollers (Ra 0:076 ìm) is opposite to that in rough rollers (Ra 0:463 ìm). The asperity height of the smooth rollers was increased by wear testing irrespective of run-in; however, run-in enhanced the increase in surface roughness. The extreme-pressure additive concentration instead of run-in was the decisive factor in electrical resistance. Friction coefficients during testing showed a strong positive relation with composite surface roughness.

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Section: Introductionmentioning

confidence: 82%

Tribological effects of roughness and running-in on oil-lubricated line contacts

Chou

Lin

1997

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…The running-in period may contribute substantially to the increase of the equipment lifetime. Some authors refer to the increase in wear after the running-in period [6][7][8][9].…”

Section: Failure Rate Base λ(0)mentioning

confidence: 99%

Importance of the Running-In Phase on the Life of Repairable Systems

Beleulmi¹,

Boutarfaïa²,

Lachi³

2014

ENG

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The running-in phase is the first stage of the bearing lifespan. However, this phase is very short and extremely important for the future lifespan of the rolling bearing because it is what sets the stabilized state in terms of roughness of the parts in contact, residual geometry and surface residual stresses, which are key factors in the fatigue resistance of mechanical parts. Several numerical and experimental studies have highlighted the importance of the running-in phase in two scales (macroscopic, meso and microscopic). Due to its high flexibility, the approach presented in this work is a numerical modeling of the running-in phase which has been based on the Weibull distribution. The obtained results confirm the importance of the running-in phase on the lifespan of bearings or other mechanism whose functioning requires an adaptation phase of parts in contact. It also concludes that if the running-in phase has been performed correctly, there is a marked improvement in reliability. The curves describe the useful saved time of lifespan according to the scale of the running-in phase.

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“…These are the criteria of friction power, friction power intensity and critical local temperature. The limits of thin film lubrication have been examined (Czichos, 1974) and a lot of work has been carried out to assess the effect of surface topography on scuffing behavior of engineering surfaces (Begelinger and DeGee, 1981; Staph et al , 1973; Barwell et al , 1977; Cogdell et al , 1987; Park and Ludema, 1994; Kelly et al , 1992). It was concluded through these works that increasing surface roughness decreases the scuffing load but the plasticity index may not be the right parameter to characterize the effect.…”

Section: Study Of Scuffingmentioning

confidence: 99%

“…Further, the effect of roughness pattern has not been studied and no conclusive method of modeling the effect of surface roughness on level of scuffing has been proposed. Running‐in of surfaces increases scuffing resistance because it decreases surface roughness (Kelly et al , 1992).…”

Section: Study Of Scuffingmentioning

confidence: 99%

Some studies on scuffing in boundary lubricated sliding contact with subsurface plastic deformation

Prakash

Rao

Sethuramaiah

2007

Industrial Lubrication and Tribology

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PurposeTo study the nature of scuffing in boundary lubricated sliding contacts with subsurface plastic deformation, as it occurs in plastic deformation processing.Design/methodology/approachLow speed oblique plastic impact testing (LOSOPIT) has been conducted on copper specimen with a hard En31 ball in a test rig that has facility to measure the coefficient of friction. Based on the findings of friction coefficient in these experiments, friction power has been estimated and was found to be in the typical range. Scuffing studies were undertaken both by observation of the slid surface of En31 sphere in a ferrographic microscope with camera facility as well as by calculation of the friction power.FindingsThe boundary lubricant was found to have profound role in safeguarding the surface from severe deformation and micro‐cracks. Scanning electron microscope (SEM) examination of the craters produced by LOSOPIT has given evidence that using the boundary lubricant resulted in smooth transfer of shear stress from the sphere to the specimen surface through the boundary lubricant layer. Owing to this, the asperities have been found flattened in a smooth manner instead of metal at the surface being scuffed. A limited amount of reduction was found in the coefficient of friction due to the use of boundary lubricant from that in the dry testing.Research limitations/implicationsThe model used to estimate the friction power is predominantly governed by the friction coefficient itself rather than either the normal load or the sliding speed. Friction coefficient itself may be contributed by various mechanisms all of which may not equally contribute to scuffing. Study is underway to carefully glean out those components of friction that exactly result in scuffing, and to use more effective criteria for scuffing.Practical implicationsThe knowledge and data developed in the paper give a clear explanation of conditions under which scuffing can take place in sliding contacts operating under boundary regime. The most important applications are metalforming and metal cutting. It is relevant to mechanical engineering machinery in which intense contact pressures are expected.Originality/valueThis paper fills the gap of lack of scuffing studies in plastic deformation processing. All earlier studies focused on elastic conditions prevailing at the contact. Since, industry has been witnessing a need to tackle the severe problems related to formed product quality and certain defects hitherto unexplained, this paper gives a new direction to explain the defects in products from scuffing point of view. In this paper, it has been shown that friction power can be a good criterion to represent scuffing intensity in boundary lubrication.

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Running-In and the Enhancement of Scuffing Resistance

Cited by 15 publications

References 7 publications

Tribological effects of roughness and running-in on oil-lubricated line contacts

Tribological effects of roughness and running-in on oil-lubricated line contacts

Importance of the Running-In Phase on the Life of Repairable Systems

Some studies on scuffing in boundary lubricated sliding contact with subsurface plastic deformation

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