The Effect of Cleanliness on the Attainable Bearing Life in Aerospace Applications

Ebert, Franz-Josef; Poulin, P.

doi:10.1080/10402009508983479

Cited by 15 publications

(4 citation statements)

References 2 publications

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“…Their results indicate that, when the particle size to film thickness ratio is varied, not only do the wear rates of the solid surfaces change, but also the mechanism of material loss. Ebert and Poulin (1995) have outlined a method to define cleanliness with the help of a cleanliness factor and a contamination factor. These factors can then be entered into a bearing life calculation method to quantity the effect of system cleanliness/contamination on the attainable life.…”

Section: Influence Of Iron Particle Contaminationmentioning

confidence: 99%

Grease‐lubrication of roller bearings in railway waggons. Part 2: laboratory tests and selection of proper test methods

Lundberg

Berg

2000

Industrial Lubrication and Tribology

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New, undestroyed greases of the same brands as those used in a field test, described in Part 1, were examined using conventional methods, such as the SKF V2F test, the roll stability test (ASTM D‐1831), the Grease Worker (ASTM D‐217), the torque test (ASTM 1478‐91), bleeding measurements ( IP 121), yield stress measurements, the 4‐ball test (ASTM D 2266‐86), base oil viscosity measurements, thickener content and the cone penetration test (ASTM D217‐88). The greases have also been tested with several new test methods developed at the University. A specification for relevant testing methods was drawn up and the connections between the tested parameters were investigated. It was found that the mechanical stability could be predicted with a combination of ASTM D‐1831 and the limiting shear stress coefficient γ. This coefficient is capable of predicting wear. It was found that the bearing temperature could be predicted by using the base oil viscosity.

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Section: Influence Of Iron Particle Contaminationmentioning

confidence: 99%

Grease‐lubrication of roller bearings in railway waggons. Part 2: laboratory tests and selection of proper test methods

Lundberg

Berg

2000

Industrial Lubrication and Tribology

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“…As a result, the majority of failures tend to be surface initiated, so the focus of damage has been on tribological aspects rather than structural change. 26…”

Section: Materials Selectionmentioning

confidence: 99%

Bearing steel microstructures after aircraft gas turbine engine service

Nygaard

Rawson

Danson

et al. 2014

Materials Science and Technology

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The microstructure of aircraft gas turbine engine bearing steel has been characterised after service in Rolls-Royce Trent™ engines, with the focus on surface condition and the consequences of sliding contact. Carbide populations at the surfaces of rolling elements are found depleted by 30% after 30 000 h engine service. A single ball failure occurred after this period, leading to fatigue spalling that initiated below the contact surface. Comparisons between unused bearing raceways and those that have experienced service revealed that the microstructures resulting from secondary hardening remain remarkably stable. Plastic flow along the direction of rolling is confined to a shallow zone <2 μm beneath the contact surfaces. Transmission electron microscopy has revealed a new deformation mechanism in these bearing steels, in the form of mechanical twinning at interfaces and prior austenite grain boundaries. It is demonstrated that workhardening occurs to a depth of 1 mm in the raceway that has experienced 30000 h service.

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“…Their results indicate that, when the particle size to film thickness ratio is varied, not only do the wear rates of the solid surfaces change, but also the mechanism of material loss. Ebert and Poulin (1995) outlined a method to define cleanliness with the help of a cleanliness factor and a contamination factor. These factors can then be entered into a bearing life calculation method to quantity the effect of system cleanliness/contamination on the attainable life.…”

Section: Electronic Accessmentioning

confidence: 99%

A study of sample withdrawal for lubricated systems. Part 1: influence of flow characteristics, sampling techniques and locations

Berg

2001

Industrial Lubrication and Tribology

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The wear of a machine element, whether it is due to fatigue or abrasive wear, will add contaminants in the form of particulates to the system. If a machine element is starting to wear out it will produce a large amount of particles and it will finally break down. Since this can be very costly, one can establish the need to monitor the system so that one can foresee failure. There are many different ways to monitor a system, e.g. measurements of the temperature, pressure, vibrations and the degree of contamination. The purpose of contamination control is to extend the life of a component and thereby save money. When monitoring a system it is very important that the monitoring control instrument should give the right output. One important factor in achieving this is the withdrawal of a representative oil sample. In this paper an investigation of where and how to take a representative sample is performed using Stokes’ law and the migration of spheres in a channel. A generalised sedimentation chart for different oils and particles is introduced. Sampling routines for proper sample withdrawal are also presented.

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The Effect of Cleanliness on the Attainable Bearing Life in Aerospace Applications

Cited by 15 publications

References 2 publications

Grease‐lubrication of roller bearings in railway waggons. Part 2: laboratory tests and selection of proper test methods

Grease‐lubrication of roller bearings in railway waggons. Part 2: laboratory tests and selection of proper test methods

Bearing steel microstructures after aircraft gas turbine engine service

A study of sample withdrawal for lubricated systems. Part 1: influence of flow characteristics, sampling techniques and locations

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