Bearing is a fixed part in the machinery, is the main part of the machinery, its role is basically used to maintain the center of the shaft, and control the movement of the machinery.NTN bearings play a pivotal role in any machinery. Without them, machinery cannot run.
Many users have reported that, when using bearings, NTN bearing heating fault is the most common, this fault will affect the life and performance of the NTN bearing.So, how does this breakdown come about?Below, it is the knowledge that summarizes come out for everybody.
1, the oil level is too low, lubricant from the oil seal loss;
2. The grease in the NTN bearing box is completely filled or the oil level is too high.This can lead to excessive lubrication, high temperature or oil leakage;
3. Contact (friction) oil seal is too dry or spring is too tight;
4, NTN bearing box hole is not round;Bearing box distortion;The supporting surface is not flat;The inner diameter of the box hole is too small;
5. Contact type (friction) oil seal is too dry or spring is too tight.
1. Selection and control of tolerance of shaft and NTN bearing chamber
The NTN bearing should rotate flexibly without blocking feeling after being pressed into the bearing.If there is obvious rotation inflexibility, it indicates that the size of the shaft is too large, and the tolerance should be reduced.If there is an obvious sense of "rustling" when the bearing is pressed into the shaft by hand, it may be because the tolerance of the shaft is too large or the roundness of the shaft is not good.Therefore, when controlling the tolerance of shaft and NTN bearing chamber, roundness should also be controlled well. At present, many domestic manufacturers only control the tolerance, but do not control roundness.
2. Assembly method of NTN bearings
Because NTN bearing is a high-precision product, improper assembly is easy to cause damage to the bearing channel, resulting in bearing damage.NTN bearing in the assembly should be a special mold, can not be knocked at will, when the shaft can only be pressed into the small circle of stress, pressure on the big circle can only be large circle of stress.The assembly requires the use of air pressure or hydraulic pressure, the upper and lower die should be outside the horizontal state, if there is an inclination will lead to damage of the NTN bearing channel due to stress, and make the NTN bearing lead.
3. Prevention of foreign body assembly
NTN bearing in the rotor to do dynamic balance when it is easy to dynamic balance when the iron filings into the bearing internal, so it is best to do dynamic balance before the bearing.In order to facilitate assembly, some manufacturers paint some oil or grease in the bearing room during assembly for lubrication effect, but often the operator is difficult to control the quantity, if the oil or grease in the bearing room accumulated more, it is easy to enter the NTN bearing along the shaft when the bearing rotates.Bearing room is best not to oil or grease, such as non - coating must not be controlled in the NTN bearing room accumulated.
4. Prevention of rust
The characteristic of paint rust is mostly in sealed motor. The sound of motor during assembly is very good. However, after some time in the warehouse, the abnormal sound of motor becomes very big.Before many manufacturers will think that the problem is the bearing, after our continuous publicity, now the factory has realized that the main problem is the insulation paint.The main reason for this problem is that the acidic substance volatilized from the insulating paint forms corrosive substance under certain temperature and humidity, which corroded the channel of the NTN bearing and led to the damage of the NTN bearing.The problem can only be the selection of good insulation paint, and after drying ventilation for a period of time after assembly.