Greases for Plain and Roller Bearings
Application and requirements
A bearing is a component that connects machine elements which move relatively to each other. In this case, forces must be absorbed or derived, but movements must also be permitted or limited.
There is a general distinction between roller and plain bearings. In contrast to the roller bearings plain bearings allow rotational and sliding movements of a shaft in a matching bearing shell, which are separated only by a lubricant or by a coating. The shaft has a flat contact with the bearing shell.
In roller bearings usually cage-guided rolling elements, such as balls or rollers, provide for a point or linear contact. Roller bearings have, compared to plain bearings, significantly lower friction losses due to the smaller contact surface and the prevailing rolling motion on there. Roller bearings are mainly grease-lubricated and can therefore be operated without major sealing effort also open or capped. For life applications, sealed or plastic-coated bearings are used with an initial grease.
The lubricating grease selected according to the application, operating temperature, employed materials and sealants and further properties plays always a decisive role.
What is an EP grease?
EP (extreme pressure) lubricating greases are greases that contain special, so-called EP active substances (EP additives or solid lubricants). Thus, a higher load-carrying capacity can be achieved, as is necessary, for example, in guide roller bearings in a continuous casting application. A very good example for this special property is RENOLIT CX-EP 2.