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Precautions for Bearing Installation

Keep the bearing and its surrounding environment clean, even invisible small dust in the bearing will increase the wear, vibration and noise of the bearing.
When using and installing bearings, be careful. It is not allowed to punch hard, strike the bearing directly with a hammer, or transmit pressure through rolling elements.
Use proper and accurate installation tools, try to use special tools, and try to avoid using cloth and short fibers.
To prevent the bearing from rusting, when taking the bearing directly by hand, the sweat on the hand shall be fully cleaned, and the bearing shall be coated with high-quality mineral oil before operation, especially in rainy season and summer.

Bearing Installation Methods

Thermodilatometry: it is recommended to use induction heating, which is uniform, efficient and clean.
Oil tank heating:
1.Heat the bearing not exceed 120℃;
2.To avoid direct contact with the bottom of the oil sink, place the bearing on the metal mesh or hang it.
3.In order to avoid difficulties in installation due to cooling of inner ring during operation, the heated bearing can be 20 ℃~30 ℃ higher than the required temperature.
4.After cooling down after installation, there will be axial contraction. In order to avoid the gap between the inner ring and the shaft shoulder, the nut on the shaft or other appropriate methods can be used for compressing.

Questions During Roller Bearing Installation

Ask: Any requirements for installing surface and site?

Answer: Yes. Any foreign particles such as iron chips, burrs, dust; etc. entering the bearing may cause noise and vibration, or even damage the bearing raceways and rolling elements. Therefore, before the bearing installation, you must ensure the cleanness of the installation surface and the environment.

Ask: While lubricating the bearing, is it better to use more grease?

Answer: It is a common mistaken concept that while lubricating the bearing, the more grease used, the better the lubrication is. Too much grease in the bearing and the bearing housing will lead to excessive churning which results in extremely high temperature.

Ask: Does the bearing have to be cleaned before installation?

Answer: As the bearing surface is coated with antirust oil, you must clean the bearing carefully with clean gasoline or kerosene, and then coat it with clean lubricating grease of superior quality or high speed before installation and operation. Cleanness is a crucial factor for the bearing life, vibration and noise. However, one point should be paid special attention: Sealed bearings do not need to be cleaned before installation.

Ask: How to install and Remove a bearing?

Answer: Hammering on the bearing end face and the non-thrust face is not allowed during bearing installation. A block, a sleeve or other installation tools should be used instead to distribute the installation force evenly on the bearing. The installed surface could be coated with lubrication oil to smooth the bearing installation. If it is a tight interference fit, the bearing should be heated to 90 ~100℃ in the mineral oil. Start installing the bearing immediately after heating. If any difficulty occurs in removal, you are suggested to use removal tool to draw outward while spraying hot oil carefully to the bearing inner ring. The heat will expand the bearing inner ring, which makes it easier to disassemble.

Ask: How to choose grease?

Answer: Lubrication has an extremely important effect on the bearing operation and bearing life. Here we’d like to make a brief introduction to the general principles on how to choose a type of grease. Greases consist of base oil, a thickening agent and additives. Different kinds and brands of the same grease may differ greatly in performance; special attention should be paid to the limiting speed of the grease. The main property of the grease depends on the base oil. Generally, Low-viscosity oil is used for high-speed or low ambient-temperature applications. High viscosity oil is used for high load or high-ambient-temperature applications the thickener also affects the lubricating property, whose water tolerance determines the water tolerance of the grease. In principle, greases of different brands should not be mixed. Also, even greases with the same thickener exert adverse effects to each other due to different additives.

Ask: Is less bearing radial clearance better?

Answer: Not all bearings require the smallest working radial clearance. You must choose appropriate clearance according to the application. In the international standard 4604－93, the radial clearance of rolling bearing is divided into five groups, i.e. group 2, group 0, group 3, group 4 and group 5, with the clearance value growing from small to large, among which group 0 is the standard clearance. Standard radial clearance is applicable to general operating conditions, conventional temperature and interference fit; bearings operating under special conditions such as high temperature, high speed, low noise, low friction, etc. should operate with larger radial clearance; bearings for precision spindles, machine tool spindles, etc. should operate with smaller radial clearance or negative clearance. Bearing operating clearance is smaller than the original clearance before installation because there is applied load on the bearings, coupled with elastic deformation incurred by bearing fitting and loading.