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NTN Self-aligning Ball Bearing Installation Failure Detection

Source: FAG bearings  Tags: News

After the installation of NTN bearings is completed, in order to check whether the installation is correct, a running inspection is required. Small machinery can be rotated by hand to confirm whether it rotates smoothly. The inspection items include poor operation due to foreign objects, scratches, and indentations, unstable torque due to poor installation, poor processing of the mounting seat, excessive torque due to too small clearance, installation errors, and seal friction, etc. Wait. If there is no abnormality, power operation can be started.

The power operation starts from the no-load low speed and gradually increases to the rated operation under the specified conditions. The items to be checked during the trial operation are whether there is abnormal sound, temperature change of the self-aligning ball bearing, leakage or discoloration of lubricant, etc. If an abnormality is found, the operation should be stopped immediately, the machine should be inspected, and the bearing should be removed for inspection if necessary.  ERIC BEARING LIMITED have rich stock for NTN 1206 , see below bearing photos .

1. The installation and adjustment of low-noise

NTN bearings can also imitate the grouping method of long-life bearings, so that the size of the interference fit is more consistent, and the clearance of the bearing is also more consistent. I hope that the interference fit can take a smaller value within the possible range , To ensure that the deformation of the bearing raceway is small, so that the noise caused by the passing of the rolling element becomes smaller.

2. The clearance has a great relationship with noise.

The ideal state is that when the NTN bearing is in the highest temperature state of operation, the clearance value is just zero. The methods for judging the excessive clearance are: the axial displacement of the self-aligning ball bearing in a static state, the reciprocating amplitude is large, and a large and heavy turbid noise is emitted during operation.

3. If an unpleasant sharp howling noise is emitted during operation, it means that the preload of the NTN bearing is too large, and the bearing has a large pre-interference.

The preload should be slightly relaxed. If the clearance is too large, the two bearing rings can be slightly offset in the axial direction: both reducing the clearance and increasing the axial rigidity can reduce the bearing noise.

4.When the rolling body enters the no-load zone, it will slip or move left and right, which will increase the noise and cause wear, and the small clearance and large axial stiffness can eliminate this phenomenon. 

But the clearance should not be too small, so as not to cause excessive temperature and shortened life.

5. Sometimes due to the large operating temperature range of the host, or the large dispersion of the size of the shaft and the bearing seat hole, it is impossible to obtain a more appropriate clearance in one adjustment. In this case, the outer ring of the self-aligning ball bearing can be adjusted. Using elastic constant pressure preloading method.

The joint venture of NTN bearing and shaft is generally a transition joint venture, and the joint race of seat ring and bearing seat hole is generally a gap joint venture. The center shaft ring of the two-way bearing should be fixed on the shaft to avoid transitions related to shaft migration. The bearing installation method is usually the situation of shaft modification, so the joint venture between the inner ring and the shaft is a win-win joint venture, and the joint venture between the bearing outer ring and the bearing chamber is a gap joint venture.

When installing the bearing, first fix the dial indicator to the end surface of the box shell, so that the contact of the watch moves on the bearing ring raceway and transfer the bearing. Check the pointer of the dial indicator while the transfer is changing. If the pointer is deflecting, clarify the shaft The circle and the center line of the shaft are not perpendicular. If the case hole is deep, you can also use the extended dial gauge to hone. This is a good way to hone the verticality of the shaft ring and shaft centerline. 

The bearing device is reversed, not only the NTN bearing is not working properly, but the joint surfaces will be severely worn. Because the difference between the shaft ring and the seat ring is not obvious, special care should be taken in the assembly, and it cannot be reversed. The accurate time division of the device should be that its seat ring can actively adapt to the rolling of the rolling body to ensure that the rolling body is located in the upper and lower raceways. 

In addition, there should be a 0.2-0.5mm gap between the seat ring of the self-aligning ball bearing and the bearing housing hole to compensate for errors caused by parts processing and inaccurate equipment. When the bearing ring is in the middle during operation When moving, this gap can ensure its active adjustment, avoid contact friction, and make it operate normally. Otherwise, it will cause serious damage to the bearing.

NTN bearing installation affects bearing performance and life

NTN bearing is one of the important components on construction machinery. Poor installation will affect its use effect and even cause failure of construction machinery equipment.

If foreign materials such as iron filings, burrs, and dust enter the bearing, the bearing will generate noise and vibration during operation, and may even damage the raceway and rolling elements. Therefore, before installing the bearing, you must ensure that the installation surface and the installation environment are clean. 

Lubrication has a very important effect on the operation and life of NTN bearings. Grease is made of base oil, thickener and additives. The performance of the grease is mainly determined by the base oil. Generally low viscosity base oil is suitable for low temperature and high speed; high viscosity is suitable for high temperature and high load.

Thickener is also related to lubricating performance. 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 of the same thickener can have bad effects on each other due to different additives. The bearing surface is coated with anti-rust oil, which must be carefully cleaned with clean gasoline or kerosene, and then coated with clean high-quality or high-speed high-temperature lubricating grease before installation and use. Fully enclosed bearings do not need to be cleaned and oiled.

After the NTN bearing is installed, if the alignment is not performed carefully, the alignment may cause the bearing to suffer additional load, friction and vibration. These may accelerate fatigue and reduce the service life of bearings, and may damage the life span of other machine parts. In addition, increased vibration and friction may greatly increase energy consumption and the risk of premature failure.

During use, the basic external conditions for bearing operation must be monitored frequently, such as temperature, vibration and noise measurements. These regular inspections will detect potential problems early and will prevent unexpected machine stoppages, enable production planning to be realized, and increase plant productivity and efficiency.

During operation, the bearing requires correct relubrication to perfect its performance. NTN bearing lubrication methods are divided into grease lubrication and oil lubrication. In order to make the bearing function well, first of all, it is necessary to choose a lubrication method suitable for the conditions of use and purpose of use. If only lubrication is considered, the lubricity of oil lubrication is dominant. But grease lubrication has the advantage of simplifying the structure around the bearing.