As a high-tech petroleum product, grease plays an important role in the rapid development of the national economy, cutting-edge science and technology and the development of the national defense industry. The research and development of new grease products and production processes is the most interesting.

Grease, lubricating oil and solid lubricant are the three most important lubricating materials at present. The properties and application conditions of the three lubricating materials are different, and they are basically not interchangeable. In general, grease lubrication should be selected under the following conditions:

（1）It is required that the lubricant must be kept on the lubricating part, and the lubricating part has no oil tank or oil box for storing the lubricant;

（2）It is required that the lubricant not only has a lubricating function, but also has a sealing function to prevent mechanical impurities and moisture from entering the lubricated parts;

（3）The limit value of the sliding linear speed of the grease lubricated bearing (that is, the bearing diameter dn) is less than 350000;

Compared with lubricating oil, the main advantages of using grease lubrication are as follows:

（1）When lubricating with grease, complex sealing devices and oil supply systems are not required, which can greatly simplify the peripheral size of the bearing, which is beneficial to the miniaturization and light weight of the equipment;

（2）The grease has good adhesion and can work on open and poorly sealed friction parts;

（3）Long service life of grease;

（4）Greases have a wider range of film thicknesses than oils.