For bearings, lubrication is very important. The use of grease can reduce friction. Excellent high-temperature oxidation stability can ensure the long-term normal operation of the lubricated parts at high temperatures, provide comprehensive protection to the bearing, and greatly extend the service life of the bearing. However, during mechanical operation, due to the working conditions (load, speed, temperature), working conditions (continuous operation, intermittent operation, vibration and shock, etc.) and working environment (humidity, temperature, pollution degree, etc.) during bearing rotation and friction The choice of grease will also be different. So, what requirements should the selection of bearing grease meet?
1. The use temperature of the grease should be at least 20-30 degrees lower than its dropping point
When the use temperature is high, the grease with good oxidation resistance, low evaporation loss and high dropping point should be selected. When the operating temperature is low, low starting torque and relatively low viscosity grease should be selected. For example, grease based on synthetic oil.
2. The selected grease should be compatible with the use speed of the lubricated friction pair
At high speeds, use low-viscosity base oils with greater penetration. For low-speed grease, you should choose a grease with a high penetration grade made of a high-viscosity base oil.
3. The selected grease should be suitable for the load
For heavy loads, a grease with high base oil viscosity and high thickener content should be selected. When the load is particularly heavy, care should be taken to select grease with extreme pressure additives or fillers (molybdenum disulfide, graphite). For medium and low loads, grease with a short, medium viscosity base oil of No. 2 consistency soap fiber structure is generally used
4. The selected grease should be compatible with the environmental conditions used
In an environment where the air is humid or in contact with water, greases with good water resistance such as calcium-based, lithium-based, and lithium complex-based should be used. When there is a lot of dust, you should choose a thicker and harder (that is, a higher grade) grease, which has better sealing performance and can prevent impurities from mixing into the friction pair. In a strong chemical environment, synthetic oil greases that resist chemical media such as fluorocarbon grease should be used.
5. The selected grease should be compatible with the grease supply mode of the friction pair
When it is a centralized grease supply, you should choose 00～1 grease. For parts where grease is regularly filled with grease guns, grease cups, etc., grease No. 1 to No. 3 should be selected. For long-term use without changing the grease, you should choose No. 2 or No. 3 grease.
6. The selected grease should be compatible with the working state of the friction pair
For example, when the vibration is large, use high-viscosity, adhesive and vibration-damping grease, such as high-viscosity cycloalkyl or compound soap-based grease thickened with mixed base lubricating oil.
7. The selected grease should be suitable for its purpose of use
The grease used for lubrication must be specifically selected according to the type of friction pair, working conditions, working conditions, environmental conditions and grease supply methods. For protective grease, it should be able to effectively protect metals from corrosion. For example, to protect parts in contact with seawater, aluminum-based grease with strong adhesion and water resistance should be selected. General protection grease can be made of solid hydrocarbon thickened high-viscosity base oil. For the sealing grease, attention should be paid to its resistance to the solvent of the sealed medium.
8. The selected grease should be as good as possible to reduce the variety of grease
In the case of meeting the requirements, try to use lithium-based grease, complex soap-based grease, polyurea grease and other multi-purpose general-purpose greases. In this way, the variety of grease is reduced, the management of grease is simplified, and the long service life of pleiotropic grease can reduce the cost of grease, reduce maintenance costs, and improve economic benefits.
The above is the answer to what requirements should be met for the selection of bearing grease. In daily bearing maintenance and repair, various types of grease are used, including sodium-based, calcium-based, lithium-based, barium-based, aluminum-based grease, etc. Etc. to ensure the normal operation of bearings and other components