Bearing grease pollutants and water analysis

In order to select grease, high temperature applications must consider the thermal stability, oxidation resistance and temperature limit. In not lubrication applications, the operating temperature above 121 ° C, choose refined mineral oil or stable performance of synthetic oil as base oil is very important. Table 28. When the rolling bearing grease temperature range of pollutants grits model runs in a clean environment, bearing damage on the surface of the rolling contact fatigue is the main original. However, when the particle pollution into the bearing system, can cause the same damage such as scratches, this phenomenon will shorten the service life of bearing. When environmental pollutants or applications in some parts of metal burr polluted lubricant, wear and tear will be the main cause of bearing damage. If, as a result of the lubricant particle pollution reasons, bearing wear becomes significant, key bearing size can change, it will affect the running of the machine. Bearing in the contaminated lubricant is running, the initial wear rate higher than the wear rate of non pollution running lubricant. But when the lubricant no longer further intrusion, the wear rate will decrease quickly, because in the normal operation of pollutants by bearing contact surface, the size of the pollutants will narrow. Moisture and moisture is one of the important factors result in bearing damage. Grease can provide a kind of protective measures against such damage. Some grease, composite calcium and composite aluminum base grease, for example, has a high resistance to water. Sodium base grease can dissolve in water, therefore cannot be used in water applications. Lubricating oil dissolve in water or suspended water can be fatal influence on fatigue life of bearing. It makes the bearing corrosion, and corrosion will reduce the bearing fatigue life. About the exact mechanism of water can reduce the fatigue life has not yet been fully understand. But someone has put forward Suggestions, water will enter the bearing rolling on micro cracks, the generation of micro cracks are caused by repeated cyclic stress. Micro cracks that can lead to corrosion and hydrogen embrittlement, make the crack extension to unacceptable greatly reduce the time needed for crack size. Transformation of water-base fluid, such as water glycol and milk has also shown that the bearing fatigue life. Although from the water and pollution of water is not the same, but the results support the previous argument about water pollution lubricant.