Localized fretting 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, separate, and form wear particles, which may then be oxidized; 2) the wear particles cause abrasive wear. The resulting wear is in the form of depressions that appear similar to Brinell depressions obtained with static overloading. (See also Fretting).
Fatigue refers to the initiation and growth of cracks due to cyclic loading.
The ability of lubricating grease to flow under suction in a dispensing pump at a rate at least equal to pump delivery capacity. When the feed of grease is not satisfactory, cavitation can occur at the inlet to the dispensing pump. In such cases, feedability can often be improved by the use of follower plates.
Soap thickeners form microscopic fibers in lubricating grease. Some soaps crystallize in the form of threads, which are 20 or more times as long as they are thick. (Most soap fibers are microscopic in size, so that the grease appears smooth to the eye). Some greases have a fibrous appearance when fiber bundles are large enough to be seen by the unaided eye. The most common fibrous lubricating greases contain sodium based thickeners, although not all sodium base greases are fibrous. (See also Appearance and Texture).
An extremely small fiber, barely visible even at maximum magnification of an electron microscope. Fibrils may collect in bundles to form larger fibers.
A material added to a grease to increase bulk or density. Examples of fillers are talc, pigments, and carbon black.
The ability of a film of lubricant to resist rupture due to load, speed, and temperature.
A plate fitted to the top surface of lubricating grease in a container and designed to assist delivery of grease to the inlet of the dispensing system.
A term used casually to refer to lubricants certified by NSF International for use primarily in food and beverage, personal care product, and pharmaceutical processing applications.
Any lubricant that has received H1designation from NSF for use “above the line” in manufacturing and packaging food, beverage, personal care, and pharmaceutical products
In ASTM D2596, the applied load at which the lubricant can no longer prevent metal-to-metal contact, and the standard steel balls used in the test weld together.
Under conditions of fretting wear, fretting corrosion occurs between a bearing inner ring and shaft or the outer ring and housing. The corrosion occurs at points where the fit is too loose. When the fit is too loose, the metal oxide film can be worn away, allowing oxygen to attack the underlying metal. The build-up of corrosion products can cause severe bearing damage, including cracking of bearing rings.
A form of wear caused by vibratory or oscillatory motion of limited amplitude and characterized by the removal of fine particles from the rubbing surfaces. Fretting wear is often followed by localized oxidation, hence the term Friction Oxidation. (See also False Brinelling and Fretting Corrosion).
The force resisting relative motion between two surfaces that are in contact.
See Fretting Wear.