9 reasons for Timken bearing sound
9 reasons for Timken bearing sound
2022年4月22日
Static load action of NSK bearing equivalent
Static load action of NSK bearing equivalent
2022年4月23日

Three factors affecting NSK bearing failure

  • For the use of bearings, noise is very common. Even the low-noise bearings in the imported Koyo bearings have the same situation. So why does it make noise? Today I will introduce its essence to you.Three factors affecting NSK bearing failure
  • The raceway sound of Koyo imported bearing and its control method raceway sound is a smooth and continuous sound generated by the rolling body rolling on the raceway surface when Koyo imported bearing is running. It is a unique basic sound that will occur in all rolling bearings. The general bearing sound is the sound of raceway plus other sounds.Three factors affecting NSK bearing failure
  •  The raceway sound of ball bearing is irregular, and its frequency is above 1000Hz. Its main frequency does not change with the speed, but its total sound pressure level increases with the speed. For the bearing with loud raceway sound, the sound pressure level of raceway sound decreases with the increase of viscosity; For bearings with low raceway noise, the sound pressure level changes from decrease to increase when the viscosity increases to more than 20mm2 / s.Three factors affecting NSK bearing failure
  •  The greater the rigidity of the bearing pedestal, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and dominant frequency of raceway sound will increase sharply with the decrease of radial clearance. The methods to control the sound of raceway are: select low-noise bearings, that is, bearings with small waviness, and carefully select the service conditions. Raceway noise often affects the noise of the whole machinery. Reducing raceway noise can reduce the noise of the whole machinery.Three factors affecting NSK bearing failure
  • Impact sound of rolling element and its control method when the ball bearing or cylindrical roller bearing of larger model runs at low speed under pure radial load, due to the small centrifugal force of the rolling element, the rolling element in the non load area will impact the cage or raceway and make noise. Three factors affecting NSK bearing failure
  • But as the speed increases, the sound will disappear. The control methods of impact sound of rolling elements are: appropriately reduce the radial clearance, and use the bearing of cage with reasonable structure and flexible material.Three factors affecting NSK bearing failure
  • The rolling sound of imported Koyo bearings and its control method rolling sound is the harsh metal friction sound that can occur in cylindrical roller bearings on all occasions. Most of it occurs in larger types of grease lubricated bearings, which is more likely to occur in greases with degraded base oil performance and hardly occurs in oil lubrication. In addition, it is easy to occur in winter.Three factors affecting NSK bearing failure
  •  When bearing pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a specific speed range with different models and sizes, both continuously and intermittently. Special processing methods for the outer ring raceway can prevent the occurrence of rolling sound.Three factors affecting NSK bearing failure
  •  If necessary, this kind of bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, the lubricating grease with excellent performance can be used and the rigidity of the parts matched with the bearing can be improved. In order to ensure the working condition of NTN bearing, it is necessary to avoid damage as much as possible. What should we do?Three factors affecting NSK bearing failure
  • Generally, if the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidental and premature damage, which can not be resistant to use. This early damage, as opposed to fatigue life, is called the quality service limit of failure or accident. Three factors affecting NSK bearing failure
Three factors affecting NSK bearing failure

Three factors affecting NSK bearing failure

  • Most of them are caused by careless installation, use and lubrication, foreign matters invading from the outside, and insufficient research on the thermal effects of shafts and shells.Three factors affecting NSK bearing failure
  • As for the damage state of NTN bearing, for example, the clamping damage of the ring retaining edge of roller bearing can be considered as the reason. These reasons can also coincide with insufficient lubricant, unsuitable, defects of oil supply and drainage structure, intrusion of foreign matters, bearing installation error and excessive deflection of shaft.Three factors affecting NSK bearing failure
  • Therefore, only investigating the bearing damage, it is difficult to know the real cause of the damage. However, if you know the use machinery, service conditions, the structure around the bearing, the situation before and after the accident, and combined with the damage state of the bearing and several causes, you can prevent the recurrence of similar accidents. Three factors affecting NSK bearing failure
  • The use factors of Koyo bearings mainly refer to whether the installation, adjustment, use and maintenance, maintenance and repair meet the technical requirements. According to the technical requirements of Koyo bearing installation, use, maintenance and repair, monitor and inspect the load, speed, working temperature, vibration, noise and lubrication conditions of the running bearing, find out the causes immediately and adjust them to make them return to normal. Three factors affecting NSK bearing failure
  • The installation condition is one of the primary factors in the use factors. The improper installation of the bearing often leads to the change of the stress state between the parts of the whole bearing. The bearing operates in an abnormal state and ends its service life early. The internal factors mainly refer to the three factors that determine the quality of Koyo bearing, such as structural design, manufacturing process and material quality. NSK bearing plays a great role in the effect of equivalent static load. Three factors affecting NSK bearing failure
  • In a sense, it is the effect of static load with the same size and direction applied to the bearing, which makes the form of permanent deformation at the contact between rolling element and ferrule bearing large stress, while the form of large permanent deformation is the same under the condition of actual load. The change of NSK is the static load equivalent of the bearing.Three factors affecting NSK bearing failure
  • Radial equivalent static load is an equivalent radial static load. Under this load, the total amount of permanent deformation at the contact between the stressed rolling element and the raceway is the same as that under the actual load.Three factors affecting NSK bearing failure
  • The axial equivalent static load is an equivalent central axial static load. Under the action of this load, the total amount of permanent deformation at the contact between the stressed rolling element and the raceway is the same as that under the action of the actual load.Three factors affecting NSK bearing failure
  • The nature of the above static load not only keeps its action direction and load constant, but also the relative speed between the ferrules acted by the static load is zero. Equivalent static load P0 is used to judge whether plastic indentation occurs in SKF Bearing under very complex load conditions in practice.Three factors affecting NSK bearing failure
  • NSK imported bearings have different meanings for this expression, so the meaning of performance under static load has changed greatly, so as to achieve better results. This is the significance of bearing in this regard. There are many reasons for NSK bearing failure. All influencing factors in the design and manufacturing process will be related to bearing failure, which is difficult to judge by analysis. In general, it can be considered and analyzed from two aspects: use factors and internal factors.Three factors affecting NSK bearing failure
  • Use factors mainly refer to whether the installation, adjustment, use and maintenance, maintenance and repair meet the technical requirements. The installation condition is one of the primary factors in the use factors. The improper installation of the bearing often leads to the change of the stress state between the parts of the whole bearing, and the bearing operates in an abnormal state and fails early. Three factors affecting NSK bearing failure
  • According to the technical requirements of bearing installation, use, maintenance and repair, monitor and inspect the load, speed, working temperature, vibration, noise and lubrication conditions borne by the running bearing, find out the cause immediately and adjust it to make it return to normal. In addition, it is also important to analyze and test the quality of grease and the surrounding medium and atmosphere.Three factors affecting NSK bearing failure
  • Internal factors mainly refer to the three factors that determine the quality of bearings, such as structural design, manufacturing process and material quality.Three factors affecting NSK bearing failure
  • First of all, the reasonable design and advanced nature of the structure will lead to longer bearing life. The manufacturing of bearings generally goes through multiple processing processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advanced nature and stability of all the processing technologies will also affect the life of bearings. Three factors affecting NSK bearing failure
  • Among them, the heat treatment and grinding processes that affect the quality of finished bearings are often more directly related to the failure of bearings. In recent years, the research on the metamorphic layer on the working surface of bearing shows that the grinding process is closely related to the surface quality of bearing.Three factors affecting NSK bearing failure
  • The metallurgical quality of NSK bearing material was once the main factor affecting the early failure of rolling bearing. With the progress of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. Three factors affecting NSK bearing failure
  • The proportion of raw material quality factor in bearing failure analysis has decreased significantly, but it is still one of the main influencing factors of bearing failure. Proper material selection is still a factor that must be considered in bearing failure analysis.Three factors affecting NSK bearing failure
  • The main task of NSK imported bearing failure analysis is to find out the main factors causing bearing failure according to a large number of background materials, analysis data and failure forms, so as to put forward targeted improvement measures, prolong the service life of the bearing and avoid sudden early failure of the bearing.Three factors affecting NSK bearing failure
  • Power operation, starting from no-load and low speed, slowly increase to the rated operation under the specified conditions. During the test run, the inspection items are whether there is abnormal sound, FAG bearing temperature change, lubricant leakage or discoloration, etc. If any abnormality is found, stop the operation immediately, check the machinery, and remove the bearing for inspection if necessary.
  • Fag bearing temperature can generally be inferred from the external temperature of bearing pedestal. However, it is more accurate to directly measure the temperature of the bearing outer ring by using the oil hole. The bearing temperature rises gradually from the beginning of operation, and the temperature is usually stable after 1 ~ 2 hours.
  •  If the bearing is not installed properly, the temperature will rise sharply, resulting in abnormal high temperature. The reasons are too much lubricant, too small bearing clearance, poor installation, excessive friction of sealing device, etc. In the case of high-speed rotation, the wrong selection of fag bearing structure and lubrication mode is also the reason.
  • The rotation of fag bearing is checked with stethoscope, and there are strong metal noise, abnormal sound, irregular sound and other indications of abnormality. The reasons are poor lubrication, poor accuracy of shaft or bearing seat, bearing damage, foreign matter intrusion, etc. Three factors affecting NSK bearing failure
  • Using lead pressure method to detect the clearance of NTN imported bearing is more accurate than using feeler gauge, but it is more troublesome. The aluminum wire used for testing should be soft, and the diameter should not be too large or too small. The ideal diameter is 1.5 ~ 2 times of the gap. In practical work, soft lead wire is usually used for testing.Three factors affecting NSK bearing failure
  • During the inspection, first open the NTN inlet bearing cover, select the lead wire with appropriate diameter, cut it into a small section with a length of 15 ~ 40mm, put it on the journal and the interface between the upper and lower bearings, cover the bearing cover, tighten the fixing bolts according to the specified torque, then loosen the bolts, remove the bearing cover, detect the thickness of the flattened lead wire with a micrometer, and calculate the average value of the top clearance of the NTN inlet bearing.Three factors affecting NSK bearing failure
  • If the top clearance is too small, a pad can be added on the joint surface of the upper and lower tiles. If it is too large, the pad shall be reduced, scraped or the tile shall be poured again.Three factors affecting NSK bearing failure
  • Adjustment of bearing bush tightening force: in order to prevent the possible rotation and axial movement of the bearing bush during the working process, in addition to the interference and stop parts, the bearing bush must also be compressed with NTN imported bearing cover. The measurement method is the same as the top clearance measurement method. In addition to measuring the thickness of soft lead wire, the bearing bush tightening force can be calculated (expressed by the elastic deformation of the bearing bush after compression)Three factors affecting NSK bearing failure
  • Generally, the pressing force of bearing bush is 0.02 ~ 0.04 mm. If the pressing force does not meet the standard, it can be adjusted by increasing or decreasing the thickness of the gasket at the joint surface of NTN inlet bearing and bearing seat, and the pad back is not allowed to be padded.Three factors affecting NSK bearing failure
  • In addition to radial clearance, the sliding NTN inlet bearing should also ensure axial clearance. When detecting the axial clearance, move the shaft to an extreme position, and then measure the displacement of the shaft from one extreme position to another with a feeler gauge or dial indicator, that is, the axial clearance.
  • When the clearance of sliding NTN inlet bearing does not meet the regulations, it shall be adjusted. Split bearings often use shims to adjust the radial clearance (top clearance). Koyo imported bearings show strong regularity and good repeatability in their use. When the normal high-quality bearing (Koyo imported bearing) is used at the beginning, the vibration and noise are relatively small, but the spectrum is scattered and the amplitude is small, which may be caused by some defects in the manufacturing process, such as surface burrs.Three factors affecting NSK bearing failure
  • After moving for a period of time, the vibration and noise maintain a certain level, and the spectrum is very single, with only one or two times the frequency. The frequency spectrum above three times of power frequency rarely appears, and the bearing state is very stable and enters the stable working period.Three factors affecting NSK bearing failure
  • After continued operation and entering the later stage of use, the vibration and noise of Koyo imported bearing began to increase, and sometimes abnormal sound appeared, but the vibration increased slowly. At this time, the bearing kurtosis began to suddenly reach a certain value. We believe that at this time, the imported bearing of Koyo shows initial failure.Three factors affecting NSK bearing failure
  • At this time, it is required to closely monitor the imported Koyo bearing and pay close attention to its changes. Since then, the bearing kurtosis value began to decline rapidly and close to the normal value, while the vibration and noise began to increase significantly, and the increase amplitude began to accelerate. When the vibration exceeded the vibration standard (such as ISO2372 standard), the bearing kurtosis value also began to increase rapidly. 
  • When both the vibration standard and the kurtosis value also exceeded the normal value (the relative standard of kurtosis available), we believe that the bearing has entered the late fault production, and the equipment needs to be repaired in time, Replace the Koyo imported bearing.
  • Koyo imported bearings show late fault characteristics. The time from the occurrence of serious faults (generally bearing damage, such as shaft holding, burns, sand frame spalling, raceway, bead wear, etc.) is usually less than one week. The larger the equipment capacity, the faster the rotating speed, and the shorter the interval. Therefore, in the actual Koyo imported bearing fault diagnosis, once the late fault characteristics are found, the bearing fault should be determined and the maintenance should be arranged as soon as possible. Although the bearing is metal, it will also be damaged. Three factors affecting NSK bearing failure
  • No matter what hard material it is, it will be damaged, but the degree of damage is different. We all know that Timken bearings are of good quality and made of good steel. Steel is a very solid material, but it will also be damaged. Timken bearings run in the machine every day, and it is easy to damage Timken bearings due to constant friction, Therefore, we should also prevent the damage of Timken bearing, maintain the bearing well, and do not use the bearing indiscriminately, causing unnecessary losses to ourselves.Three factors affecting NSK bearing failure
  • So how to deal with the bearing damage. If the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidental and premature damage, which can not be resistant to use. This early damage, as opposed to fatigue life, is the quality service limit known as failure or accident. Most of them are caused by careless installation, use and lubrication, foreign matters invading from the outside, and insufficient research on the thermal effects of shafts and shells. Three factors affecting NSK bearing failure
  • As for the damage state of the bearing, such as the clamping damage of the ring and retaining edge of the roller bearing, these reasons can be considered. These reasons also coincide with insufficient lubricant, unfitness, defects of the oil supply and drainage structure, invasion of foreign matters, bearing installation error and excessive deflection of the shaft. Three factors affecting NSK bearing failure
  • Therefore, only investigating the bearing damage, it is difficult to know the real cause of the damage. However, if you know the use machinery, service conditions, the structure around the bearing, understand the situation before and after the accident, and investigate the damage state of the bearing and several causes, you can prevent the recurrence of similar accidents.Three factors affecting NSK bearing failure