What is the role of bearing lubrication?
First, the role of bearing lubrication
Lubrication has an important influence on the fatigue life of rolling bearings and friction, wear, temperature, vibration, etc. Without normal lubrication, the bearings cannot work. Analysis of the cause of bearing damage indicates that about 40% of bearing damage is associated with poor lubrication. Therefore, good lubrication of the bearings is an effective measure to reduce bearing friction and wear. In addition, the lubrication of the bearing also has various functions such as heat dissipation, rust prevention, sealing, and shock mitigation. The role of bearing lubrication can be briefly explained as follows:
a. Forming an oil film between the two rolling surfaces or sliding surfaces that contact each other to separate the two surfaces, reducing friction and wear on the contact surfaces.
b. When using oil lubrication, especially when using circulating oil lubrication, oil mist lubrication and fuel injection lubrication, the lubricating oil can take away most of the friction heat inside the bearing and effectively dissipate heat.
c. When grease lubrication is used, foreign matter such as dust can be prevented from entering the bearing and sealing.
d. Lubricants have the effect of preventing metal corrosion. e. Extend the fatigue life of the bearing.
Second, the comparison of grease lubrication and oil lubrication
The lubrication method of the bearing is roughly divided into two types: grease lubrication and oil lubrication. In order to fully utilize the function of the bearing, it is important to use a lubrication method depending on the purpose of use reduction and use. Table 4-2 shows the advantages and disadvantages of grease lubrication and oil lubrication. Third, grease lubrication Grease is a lubricant composed of base oil, thickener and additives. When selecting, you should choose a grease that is very suitable for the conditions of use of the bearing. Due to the different trademarks, there will be great differences in performance, so you must pay attention when choosing.
Commonly used greases for bearings include calcium-based greases, sodium-based greases, calcium-sodium-based greases, lithium-based greases, aluminum-based greases, and molybdenum disulfide greases.
The amount of grease filled in the bearing is preferably 1/2-1/3 of the internal space of the bearing. It should be reduced to 1/3 at high speed. Excessive grease will increase the temperature rise. 4. Selection of grease When selecting grease according to working temperature, the main indicators should be dropping point, oxidation stability and low temperature performance. The dropping point can generally be used to evaluate high temperature performance. The actual working temperature of the bearing should be lower than the dropping point of 10-20 °C. . Synthetic grease should be used at a temperature below the drop point of 20-30 °C.
When selecting the grease according to the bearing load, the grease with a small penetration should be selected for the heavy load. When working under high pressure, in addition to the small penetration, it also has higher oil film strength and extreme pressure performance.
