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The Inspection of INA Imported Bearings

Writer: Eric Bearing Limited

1) The quality of INA imported bearings. During the disassembly of the bearing box, first of all, check whether the grease has bad conditions such as deterioration, agglomeration, and impurities. This is an important basis for judging the cause of INA bearing damage. Secondly, check the bearing for bite and wear; check the surface finish of the INA bearing inner and outer rings, rolling elements, cages, and whether there are cracks, rust, peeling, pits, overheat discoloration, etc., and measure whether the INA bearing clearance exceeds the standard ; Check the shaft sleeve for wear, pits, peeling, if there is any of the above conditions should be replaced with new INA bearings.

2) Coordination of INA imported bearings. When the bearing is installed, the fit between the inner diameter of the bearing and the shaft, the outer diameter and the housing is very important. When the fit is too loose, the mating surface will produce relative sliding called creep. Once the creep occurs, it will wear the mating surface and damage the shaft or casing, and the wear powder will invade the INA bearing, causing heat, vibration and damage. When the interference is too large, it will cause the outer diameter of the outer ring to become smaller or the inner diameter of the inner ring to become larger, reducing the internal clearance of the INA bearing. In order to choose a suitable fit, various factors such as the nature, size, temperature conditions of the bearing load, and the rotation of the inner and outer rings must be considered.

3) Adjust the clearance of each part of INA imported bearings. If the clearance of the INA bearing is too small, the frictional loss of grease in the clearance is too large, which will also cause the bearing to heat up.At the same time, if the clearance is too small, the amount of oil will be reduced. Wen Sheng. However, if the gap is too large, the dynamic characteristics of the INA bearing will be changed, causing the rotor to run unstable. Therefore, it is necessary to select the verified INA bearing clearance for different equipment and use conditions. Guohua Taicang #8 Unit B induced fan has a long-term high bearing temperature during operation. In 2008, the C-level maintenance of the unit focused on this issue. The inspection found that the lubrication of the INA bearing, the static balance of the impeller, and the alignment of the coupling were all normal, so the focus of the investigation was on the clearance of each part of the INA bearing. After measuring the bearing thrust clearance is only 0.07mm, it is analyzed that the thrust clearance is too small as the cause of high bearing temperature.

Use a grinder to grind the thrust bearing septum ring by 0.07~0.08mm to enlarge the thrust clearance, so that the thrust clearance of the INA bearing is expanded to 0.14~0.15mm. During operation, the INA bearing temperature is normal, which completely eliminates the long-term defects and guarantees the equipment. Safe and stable operation. The long-term temperature of the INA bearings of the Yunnan Fan Electric #1 Unit's induced draft fan is too high, reaching 80 ~ 90 ℃, resulting in a greatly shortened bearing service life, and repeated replacement of INA bearings has not solved the problem. During the C-level maintenance in 2008, it was found that the gap between the shaft and the end cover shaft seal was too small. The bearing temperature was normal during the test run in the cold state, and the shaft was thermally expanded during hot operation, causing friction with the end cover shaft seal. It is analyzed that this is the reason why the temperature of the INA bearing is too high for a long time. The end cover hole is turned by 0.5mm to increase the gap between the shaft and the end cover shaft seal by 0.25mm to avoid friction between the shaft and the end cover after thermal expansion during operation. After treatment, the problem of high INA bearing temperature has been fundamentally improved.The temperature of the bearing is normal in cold and hot operation, and there is no oil leakage in the bearing box, which ensures good operating conditions of the INA bearing and reduces the INA bearing. The frequency of replacement saves on maintenance costs.  Eric Bearing Limited have INA SL185008-S3-A in stock , pls click here :


Precautions for use of INA bearings

Everyone knows that INA bearings are precision parts, and they need to be very cautious when using them, that is, they use high-performance INA bearings. If they are used improperly, they will not achieve the expected performance results, and it is easy to damage the INA bearings. Most of the INA bearings are damaged due to many reasons-exceeding the originally estimated load, ineffective sealing, excessively small INA bearing clearance caused by over-tight fit, etc. Any one of these factors has its special damage type and will leave special damage marks.

Therefore, looking at the damaged bearings, in most cases, the possible causes can be found. In general, one-third of the INA bearing damage is due to fatigue damage, and the other one-third is due to poor lubrication. The other one-third is caused by contaminants entering the INA bearings or improper installation.

First, keep the INA bearing and its surrounding environment clean

The second point is to install carefully and carefully when using the installation

Third, use appropriate and accurate installation tools

Use special tools as much as possible, and try to avoid using things like cloth and short fibers.

Fourth point, to prevent corrosion of INA bearings, do not use water bubbles

The INA bearing is made of stainless steel, but it is also afraid of water. If you don’t believe it, you should soak it in the water. Oh, when you take the INA bearing by hand, you must fully wash off the sweat on your hands and apply high-quality mineral oil. Perform operations, especially in the rainy season and summer, pay special attention to rust prevention, don't tell me what rust is afraid of, okay, try it yourself, and see what the rust will be !

The life of INA bearings has a certain number of years. If we use it well, pay attention to the above 4 points of normal use, INA bearings will fully play its role !

Some other precautions for using INA bearings are as follows:

INA bearing assembly method

Because INA bearings are high-precision products, improper assembly can easily damage the INA bearing channel, resulting in INA bearing damage. INA imported bearings should have special molds during assembly, and can not be knocked at will. When pressing into the shaft, only small circles can be used to force, and when pressing large rings, only large rings can be used. Air pressure or hydraulic pressure is required during assembly. During press-fitting, the upper and lower molds should be outside the horizontal state. If inclined, the INA bearing channel will be damaged due to force, and the INA bearing will produce a noise.

Prevention of assembly foreign objects

When the INA bearing is mounted on the rotor for dynamic balancing, it is easy for the iron chips generated during dynamic balancing to enter the INA bearing, so it is best to do dynamic balancing before installing the INA bearing. Some manufacturers apply some oil or grease to the INA bearing room for lubrication during assembly, but it is often difficult for the operator to control the amount. If oil or grease accumulates in the INA imported bearing room, the INA When the bearing rotates, it is easy to enter the INA bearing along the shaft. Japan INA bearing room is best not to be coated with oil or grease, if it is not coated, it must be controlled not to accumulate in the INA bearing room.

Prevention of paint rust

The characteristic of paint rust is that it is frequently used in sealed motors. The motor sounds very well during assembly, but after being placed in the warehouse for some time, the abnormal noise of the motor becomes very large, and there is a serious rust phenomenon when the INA bearing is removed. In the past, many manufacturers would think that it was the problem of INA bearings. After our continuous promotion, now the motor factory has realized that it is mainly a problem of insulating paint. This problem is mainly due to the formation of corrosive substances by the acidic substances volatilized from the insulating paint at certain temperature and humidity. Corrosion of the INA imported bearing channels leads to damage of the INA bearings. At present, the problem can only be to choose good insulating paint and assemble it after drying for a period of time.