I. Overview of automotive grease
Automobile grease accounts for a large proportion. From the performance requirements of automobile grease, we can see the level of grease industry in a country. Automotive wheel bearing grease is a semi-solid lubricant that has good adhesion to automotive wheel bearings and provides lubrication to friction points. At the same time, it also has the functions of waterproof, dustproof, anti-corrosion and sealing.
In recent years, automobiles are moving towards low fuel consumption, small size and light weight. The operating temperature of wheel bearing greases will reach 160 ° C, and occasionally as high as 200 ° C. Therefore, wheel bearing grease must use long-life, high-temperature-resistant grease. There are two broad types of greases used in automotive wheel bearings: calcium-based greases and lithium-based greases. Although calcium-based grease has good water resistance, pumpability and shear stability, the use of the environment temperature is low due to its existence (should be ﹤ 70 ℃); it will harden at low temperatures, affect viscosity, increase friction resistance and use Short life and other shortcomings have been eliminated in foreign countries, but some parts of automobile wheel bearings in China are still used. With the rapid development of the automotive industry, most of the current automotive wheel bearing lubrication in China has gradually started to use general-purpose lithium-based greases. The operating temperature range has been extended to -25 to 120 ° C. Compared with the use of calcium-based greases, the lubrication period can be extended. Reduce abrasion and reduce consumption, but there are still problems such as high temperature loss. Bearing oil
2. Grease for modern wheel bearing
Combining the development status of the grease industry and the automotive industry, selecting a grease with excellent performance to meet the needs of wheel bearing development is an economic measure to extend the grease change cycle and solve the high temperature loss to maintain good bearing lubrication. Jin Guan has researched and developed with great concentration, and has made products with excellent quality that fit the wheel grease:
1. Compound extreme pressure lithium-based grease is made of compound lithium soap thickened mineral oil and added extreme pressure additives. It has a very high dropping point and excellent high temperature performance, and it is not easy to lose at high temperature. It has good mechanical stability, small bearing leakage, and long service life. It has good water resistance and is suitable for lubrication in humid environments. Extreme pressure, rust prevention, pumpability and low noise. The operating temperature range is -20 to 160 ° C. The composite extreme-pressure lithium-based grease has been used in car driving tests. Some data show that after running at 2.0 × 104Km, various performance indicators are good, the color is similar to that of new grease, and no loss occurs in summer.
2. Urea-based greases Greases made from a polyurea compound thickened with -NHCON-functional base oils can be called polyurea greases. The general polyurea grease has a temperature range of -30 to 160 ° C, and the special polyurea grease has a temperature of -40 to 250 ° C, which can meet the lubrication under high temperature conditions. Polyurea does not soften and drain under high temperature, and does not block the oil road in winter. Because the polyurea thickener does not contain metal ions, unlike other soap-based thickeners, it has a catalytic oxidation effect on the base oil and can inhibit the oxidation of the base oil, so it has good oxidation resistance and long life. Polyurea has excellent extreme pressure performance, which can effectively prevent vibration and reduce friction coefficient. Urea thickener is organic, has strong hydrophobicity, and can resist the erosion of acid and alkali media. Polyurea can be used in many parts such as automobile wheel hub bearings, electrical appliances, brakes, clutches, etc. Its multi-effect and universal characteristics simplify the lubrication work. There are many raw materials for the production of polyurea grease, and the process conditions are difficult to control, which often cause quality differences. Only with suitable and reasonable formulas and processes can polyurea greases with good performance be obtained. The life of automobile wheel bearings cannot usually be determined simply by the analysis of the physical and chemical properties of grease. It is necessary to verify the applicability of wheel bearing grease through bench test and actual use test.