Usually the seals are absolutely necessary to bearings, a bearing without any sealing device, which is directly exposed to the working environment, is very harmful. Sealing can prevent the intrusion of the outside, the entry of foreign material inside a bearing, especially foreign metal often cause bearing raceway abrasive wear, affect the use of precision bearings, shorten service life of bearing, enter any bearing interior of harmful gases and water will not only cause the bearing parts of the rust, and more serious is this kind of harmful medium will affect the physicochemical properties of the damaged bearing lubricants, lubricating oil film, accelerated ageing of lubricant. The sealing device can also play a role of preventing the loss of lubrication and reduce environmental pollution.
The bearing has a certain internal clearance, but sometimes bearing group used in the installation or assembly of the bearing pairs, often apply pretightening load on the bearing, the rolling body and the inner and outer rings have certain predeformation, in order to achieve the required work objective, the bearing will be in operation under the condition of negative clearance. Negative clearance is one of the characteristics of rolling bearing is used, and for any kind of sliding bearing must work in the case of clearance.
Because the work surface of the bearing in the bearing parts assembly, installation and use of the process of scars or fatigue spalling, abnormal vibration and noise can cause bearing, so try to methods using the mounting and dismounting bearing right, to avoid accidental damage bearings, such bearings in normal use of damage and fatigue peeling, can be used to identify the abnormal vibration and noise of the bearing.
The additional seal bearing can effectively make the bearing work in good condition without external dirt intrusion, but the additional seal device can increase the axial size of mechanical mechanism, the use of the bearing and install the inconvenience, the sealing property is also the additional seal device is often influenced by the processing precision and the shaft neck and shell matched parts of tolerance, therefore demanding sealing parts in compact structure, such as motor, bearing, deep groove ball bearings have been sealed in the amount of use. Sealed bearing has good sealing performance, but also in the whole process of the operation of the bearing without make-up grease and keep good operation state, thereby reducing the cost and time of repair.


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