Bearings: Installation, Grease Selection, and Lubrication Considerations

Are there any requirements on the installation surface and installation location?

Yes. If there are iron filings, burrs, dust and other foreign matter entering the bearing, the bearing will produce noise and vibration during operation, and may even damage the raceways and rolling elements. Therefore, before installing the bearing, you must ensure that the mounting surface and installation environment are clean.

Do bearings have to be cleaned before installation?

The surface of the bearing is coated with anti-rust oil. You must clean it carefully with clean gasoline or kerosene, and then apply clean, high-quality or high-speed and high-temperature lubricating grease before installation and use. Cleanliness has a great impact on bearing life and vibration and noise. But we would like to remind you that fully enclosed bearings do not need to be cleaned and refueled.

How to choose grease?

Lubrication has an extremely important impact on the operation and life of bearings. Here we briefly introduce to you the general principles for selecting grease. Grease is made of base oil, thickener and additives. The properties of different types of grease and different brands of the same type of grease vary greatly, and the allowable rotation limits are different. Be sure to pay attention when selecting. The performance of grease is mainly determined by the base oil. Generally, low viscosity base oil is suitable for low temperature and high speed, and high viscosity base oil is suitable for high temperature and high load. The thickener is also related to the lubrication performance, and the water resistance of the thickener determines the water resistance of the grease. In principle, greases of different brands cannot be mixed, and even greases with the same thickener will have bad effects on each other due to different additives.

When lubricating bearings, is the more grease you apply the better?

When lubricating bearings, it is a common misconception that the more grease you apply, the better. Excess grease in bearings and bearing chambers will cause excessive mixing of the grease, resulting in extremely high temperatures. The amount of lubricant filled in the bearing should be enough to fill 1/2 to 1/3 of the internal space of the bearing, and should be reduced to 1/3 at high speed.

How to install and disassemble?

During installation, do not directly hammer the end face and non-stressed surface of the bearing. Press blocks, sleeves or other installation tools (tooling) should be used to evenly stress the bearing. Do not install through rolling elements. If the mounting surface is lubricated, the installation will go more smoothly. If the fit interference is large, the bearing should be placed in mineral oil and heated to 80~90°C before installation as soon as possible. Strictly control the oil temperature not to exceed 100°C to prevent the tempering effect from reducing the hardness and affecting dimensional recovery. When you encounter difficulties in disassembly, it is recommended that you use a disassembly tool to pull outwards while carefully pouring hot oil on the inner ring. The heat will expand the inner ring of the bearing, making it easier to fall off.

Is the smaller the radial clearance of the bearing, the better?

Not all bearings require minimum working clearance, you must choose the appropriate clearance according to the conditions. In the national standard 4604-93, the radial clearance of rolling bearings is divided into five groups – group 2, group 0, group 3, group 4, and group 5. The clearance values are in order from small to large, among which group 0 is the standard clearance. The basic radial clearance group is suitable for general operating conditions, normal temperatures and commonly used interference fits; bearings working under special conditions such as high temperature, high speed, low noise and low friction should use large radial clearance; for bearings working under special conditions such as high temperature, high speed, low noise, low friction, etc. Bearings for precision spindles and machine tool spindles should use smaller radial clearances; roller bearings can maintain a small amount of working clearance. In addition, there is no clearance for separate bearings; finally, the working clearance of the bearing after installation is smaller than the original clearance before installation, because the bearing has to withstand a certain load rotation, and there are also friction caused by the bearing fit and load. The amount of elastic deformation.

Post time: Jan-10-2024