Grease Lubrication of Bearings in a Humid Environment
Bearing life is one of the key challenges facing machinery designers, and lubrication is a critical part of bearing life. Grease is simply oil thickened with a thickener to produce a stable mass. It is often blended with additives, such as extreme pressure (EP) agents and anti-corrosion agents, to give it more beneficial properties. Greases are normally used in applications where the lubricant is not readily accessible to the operator and where frequent lubrication is not easy or convenient.
Grease lubrication has certain advantages over other lubricants. It is easier to apply, it can provide a continuous supply of lubricant to the bearing, protect moving parts from corrosion, reduce wear and can extend the life of the bearing. However, due to its semi-fluid nature, it is more prone to leakage or being washed away by water. This can be a major issue when used in humid or wet environments. Water mixing with grease leads to the breakdown of grease and the formation of soap or gums, which can block bearing bores and cause malfunction or seizure of the bearing.
Therefore, for bearings used in wet or humid environments, using a grease specifically designed for such applications is imperative. Such greases contain special additives, such as corrosion inhibitors, EP agents, water displacement agents, and special thickening agents, that improve performance and extend bearing life in a moist environment.
The selection of a grease for such applications should take into account a variety of factors, such as the speed, temperature and load of the bearing, as well as the type of bearing and its size. The natural tendency of manufacturers is to select a thick grease, as it can remain in the bearing longer, but this is not always the case. Greases that are too thick can create high start-up torques and increased wear of bearings under high speed conditions. Therefore, grease should be selected that is optimal for a given application.
In addition, the right packing and application are also important. For applications in a humid environment, gland packing needs to be highly resilient to water and chemicals, and should also be correctly applied to ensure that the bearing has sufficient lubrication at all times. In addition, seals should be carefully chosen, as some can absorb grease, leading to insufficient lubrication, or trap moisture that can compromise the performance of the grease.
To ensure the optimum performance of bearings in a humid environment, it is important to select the right type of grease and apply it and maintain it properly. By following the above mentioned tips, you can get the best out of your bearing in any type of environment.
