Fretting Wear Observation of Flat Contacts

Buse, Henrik; Hodúlová, Erika

doi:10.24053/tus-2021-0003

Cited by 2 publications

(2 citation statements)

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“…Only for two short test series, one with non-lubricated materials test and one lubrication paste, a comparison was performed [33] and showed nearly no differences in the results. A general statement on the effects of the intermittent contact-opening for observation must be conducted with further experiments.…”

Section: Discussionmentioning

confidence: 99%

Planar Contact Fretting Test Method Applied to Solid Lubricants

Buse

Schueler²,

Hodúlová

2021

Lubricants

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A new method of material and lubricant testing is demonstrated with a planar contact fretting wear tribometer under typical fretting wear conditions. The usual abstraction of contact geometries with an easy-to-align point or line contacts is deliberately dispensed to do justice to the frequently flat contacts of machine elements (shaft-hub connection, bearing seats, etc.). For the study, a new method of targeted observation of the contact surfaces during the test is used, which allows a time-lapse animation of the fretting wear progress of solid lubricant mixtures. Thus, the formation of possible transfer film build-up and the type of wear mechanism occurring can be visualized. This technique represents, in conjunction with additional analytical methods such as microscopy and SEM/EDX, a powerful tool to provide a better insight into the mechanisms of solid lubricant action under fretting conditions. To demonstrate the potential of this approach, a time to damage study is performed on commercial and self-prepared pastes from solid lubricants and white oil, where calcium hydroxide is a commonly employed solid lubricant for the avoidance of fretting wear is compared to other materials.

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Section: Discussionmentioning

confidence: 99%

Planar Contact Fretting Test Method Applied to Solid Lubricants

Buse

Schueler²,

Hodúlová

2021

Lubricants

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“…The test should, therefore, only be used if high local pressures and pure sliding friction are to be expected in practice. Greases may be suitable for fretting conditions in surface contact (e.g., for shaft-hub connections [35,36]) or rolling bearings, even if they do not pass the SRV test according to ASTM D7591.…”

Section: Overview and Comparisonsmentioning

confidence: 99%

Comparison of Different Standard Test Methods for Evaluating Greases for Rolling Bearings under Vibration Load or at Small Oscillation Angles

Grebe

Widmann

2023

Lubricants

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Rolling bearings operated at small oscillation angles or exposed to vibrations during standstill show typical damage after only a short period of operation. This can be false brinelling damage, so-called standstill marks or classic fretting damage (fretting corrosion, tribo-oxidation). It is important to differentiate here according to the amplitude-ratio x/2b, which indicates the ratio between the rolling element Motion (x) and the Hertzian contact half-axis (b). Depending on this ratio, suitable laboratory test methods must be used to test the lubricating grease practically for the particular application. For this purpose, the Fafnir wear test, according to the standard of the American Society for Testing and Materials ASTM D4170, is also listed in the current high-performance multi-use specification of the National Lubricating Grease Institute (NLGI) as a release test for lubricating greases. In Europe, the SNR-FEB2 test is frequently used, which is also required to release greases in the blade bearings of wind turbines, among other things. In the case of standstill marks due to very small oscillation angles or vibrations, the Mannheim Tribology Competence Center (KTM) has developed a special test now established in the industry. The oscillating angles vary in these three different standard tests in the range from ±6° in the Fafnir test to ±3° in the SNR-FEB2 test to ±0.5° in the KTM standstill marking test; the x-to-2b ratios range from 5.5 (Fafnir) to 3.4 (SNR) to 0.5 (KTM). This paper will explain the scientific basis for these special operating and test conditions and compare test results of specially prepared model greases in these three standard rolling bearing tests, two test variations and a classical fretting test under oscillating sliding friction (ASTM D7594). The paper’s main objective is to show that the suitability of grease for such an application depends strongly on the prevailing operating conditions. Different tests in this field are, therefore, not interchangeable. Good results in one test do not automatically mean good results in a similar test at first glance. Therefore, selecting the right test for the application is important.

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Fretting Wear Observation of Flat Contacts

Cited by 2 publications

References 0 publications

Planar Contact Fretting Test Method Applied to Solid Lubricants

Planar Contact Fretting Test Method Applied to Solid Lubricants

Comparison of Different Standard Test Methods for Evaluating Greases for Rolling Bearings under Vibration Load or at Small Oscillation Angles

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