ASTM D4170 test method for fretting wear protection by lubricating greases
1. Scope
1.1 This test method evaluates the fretting wear protection provided by lubricating greases.
1.2 The values stated in SI units are to be regarded as the standard. Other units are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, See 7.2, 7.3, 7.3.1, and 9.2.
2. Referenced Documents
2.1 ASTM Standards:
Test Methods for Rating Motor, Diesel, and Aviation Fuels; Motor Fuels (Section I), Reference Materials and Blending Accessories (Annex 2), Reference Fuels (A2.7.3.3), and Table 32 (Specification for n-Heptane Motor Fuel)
2.2 Military Standard:
MIL-S-22473D Sealing, Locking and Retaining Compounds, Single-Component
3. Terminology
3.1 Definitions:
3.1.1 fretting wear, n - a form of attritive wear caused by vibratory or oscillatory motion of limited amplitude characterized by the removal of finely-divided particles from the rubbing surfaces.
3.1.1.1 Discussion - Air can cause immediate local oxidation of the wear particles produced by fretting wear. In addition, environmental moisture or humidity can hydrate the oxidation product. In the case of ferrous metals, the oxidized wear debris is abrasive iron oxide (Fe2O3) having the appearance of rust, which gives rise to the nearly synonymous terms, fretting corrosion and friction oxidation. A related, but somewhat different phenomenon often accompanies fretting wear. False brinelling is localized fretting wear that occurs when the rolling elements of a bearing vibrate or oscillate with small amplitude while pressed against the bearing race. The mechanism proceeds in stages: (1) asperities weld, are torn apart, and form wear debris that is subsequently oxidized; (2) due to the small-amplitude motion, the oxidized detritus cannot readily escape, and being abrasive, the oxidized wear debris accelerates the wear. As a result, wear depressions are formed in the bearing race. These depressions appear similar to the Brinell depressions obtained with static overloading. Although false brinelling can occur in this test, it is not characterized as such, and instead, it is included in the determination of fretting wear.
