Analysis of common failures and precautions of IKO bearing
Analysis of common failures and precautions of IKO bearing
2022年4月22日
Three factors affecting NSK bearing failure
Three factors affecting NSK bearing failure
2022年4月23日

9 reasons for Timken bearing sound

  • The brand of lubricating oil shall be selected according to the requirements of the vehicle manual, and shall be replaced in time after the vehicle maintenance cycle. After discharging the old oil, the mechanism shall be cleaned before adding new oil. Installation method and precautions of IKO bearing
  • The oil shall be added to the specified marking line or flush with the oil filler (depending on the specific structure and requirements of the vehicle), and no more oil shall be added. As the world’s IKO imported bearing, it is widely used. Each industry has different characteristics of damage.9 reasons for Timken bearing sound
  • Mechanical damage
  • Mechanical damage of sliding bearing refers to the groove marks in different degrees on the alloy surface of bearing bush. In serious cases, metal peeling and large-area random scratch occur on the contact surface; Generally, contact surface damage and ablation exist at the same time. The main reason for the mechanical damage of IKOInstallation method and precautions of IKO bearingInstallation method and precautions of IKO bearing imported bearing is that the bearing surface is difficult to form oil film or the oil film is seriously damaged.9 reasons for Timken bearing sound
  • Bearing cavitation
  • Under the repeated action of cylinder pressure (impact load), the surface layer of sliding bearing will undergo plastic deformation and cold work hardening, lose the deformation ability locally, gradually form wrinkles and expand continuously, and then form cavities in the loaded surface layer with the falling off of wear debris. When the pitting is parallel to the interface, the pitting will expand gradually, and then the pitting will occur along the interface.9 reasons for Timken bearing sound
  •  The main reason for the cavitation of sliding bearing is that the sudden change of the cross section of structural elements such as oil groove and oil hole causes the strong disorder of oil flow, forming bubbles in the vacuum area with disordered oil flow, and then cavitation occurs due to the collapse of bubbles due to the increase of pressure. 9 reasons for Timken bearing sound
  • Cavitation usually occurs in the high load area of IKO inlet bearing, such as the lower bearing bush of crankshaft main bearing.9 reasons for Timken bearing sound
  • fatigue pitting
  • Fatigue pitting corrosion of IKO imported bearing refers to the fatigue damage, fatigue pitting corrosion or fatigue falling off in the middle of the bearing due to overheating and excessive bearing clearance due to overload operation of the engine. This kind of damage is mostly caused by overload, excessive bearing clearance, or unclean lubricating oil and foreign matters mixed in it.9 reasons for Timken bearing sound
  •  Therefore, when using, attention should be paid to avoid bearing overload, and do not run at too low or too high speed; Adjust the engine to a stable state at idle speed; Ensure the normal bearing clearance and prevent the engine speed from being too high or too low; Check and adjust the working condition of the cooling system to ensure that the working temperature of the engine is appropriate.9 reasons for Timken bearing sound
  • Bearing alloy corrosion
  • The corrosion area of IKO imported bearing alloy is generally that the lubricating oil is impure, and the chemical impurities (acid oxides, etc.) in the lubricating oil oxidize the bearing alloy to form acidic substances, causing part of the bearing alloy to fall off and form irregular small cracks or pits. The main causes of bearing alloy corrosion are improper selection of lubricating oil, poor corrosion resistance of bearing materials, or rough engine operation and high temperature.9 reasons for Timken bearing sound
  • Bearing melting
  • There is a small convex metal surface between the journal and the bearing friction pair, which forms a local high temperature. In the case of insufficient lubrication and poor cooling, the bearing alloy will be blackened or partially burned. This fault is often caused by the tight fit between the journal and the imported IKO bearing; Insufficient lubricating oil pressure is also easy to burn the bearing.9 reasons for Timken bearing sound
  • Outer circle of bearing
  • The outer circle of IKO imported bearing means that the bearing has relative rotation in the seat hole. After the bearing goes to the outer circle, it will not only affect the heat dissipation of the bearing, which is easy to ablate the alloy on the inner surface of the bearing, but also damage the back of the bearing and burn the bearing in serious cases. Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing9 reasons for Timken bearing sound
  • The main reason is that the bearing is too short, the tenon is damaged, and the processing or installation does not meet the specifications. Timken bearing is an important part of the rear axle drive wheel movement. Timken bearing is the main compound in the work, which can withstand bending and torque and absorb some impact loads at the same time. 9 reasons for Timken bearing sound
  • The axle integral carbon alloy quenched steel and induction heating hardening commonly used in quenching have a hardened layer depth of 4 – 6mm and a hardness of 50 ~ 55HRC. 9 reasons for Timken bearing sound
  • In the production of Timken bearings, it is found that Timken bearings are often burned out, which seriously affects the induction quenching quality of Timken bearings and parts. The test shows that the burned out area of Timken bearing is located in coil 225. Expand the regularity of fault characteristics of both sides near the construction site.9 reasons for Timken bearing sound
  • Axle sensor heating, in addition to heating the workpiece, the main heat loss in three ways is the heat generated by the sensor.9 reasons for Timken bearing sound
  • Heat radiates all around. Guide the magnet and induction coil on the insulating paint and fiberglass cloth. This form of heat loss is less, heating is uniform, and has little effect on sensor burnout.9 reasons for Timken bearing sound
  • Heat of cooling water. This part of the heat dissipation cooling sensor enables the operation of induction heating. The study found that at 0-180 degrees, the intake of low water temperature indicates good heat exchange cooling water, smooth water and no water temperature; More than 180, Because of the length of the flow path, the rise of the water temperature and the rise of the water temperature, the heat exchange changes. Because the sensor can easily lead to the temperature rise of a station (such as 225. About the part), this is the main induction coil combustion.Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing9 reasons for Timken bearing sound
  • Induction coil of the heat transfer plate, part of the plate current density, large cross-section and low water temperature, in the area of the coil of the heat transfer plate. 0 to 90 degrees and 270 – 360 degrees are far away from the nearby induction coil plate, with good thermal conductivity; Far away from the plate, the thermal conductivity is poor. The induction coil of 90 to 270 pieces makes the temperature of the induction coil in this area easier to appear in this part, like burning the coil. The heat flow of the induction coil is compared in different parts. The thermal sensing circuit in the area near 225 degrees is stored, so there is a large difference between the combustion phenomenon of induction coil in this area.9 reasons for Timken bearing sound
  • Contact fatigue failure
  • Contact fatigue failure refers to the failure caused by alternating stress on the working surface of IKO imported bearing. Contact fatigue spalling occurs on the working surface of IKO bearing, which is often accompanied by fatigue cracks. It first occurs from the large alternating shear stress below the contact surface, and then extends to the surface to form different spalling shapes, such as pitting or pitting spalling, which is called shallow spalling. 9 reasons for Timken bearing sound
  • Due to the gradual expansion of the spalling surface, it often expands to the deep layer, forming deep spalling. Deep spalling is the fatigue source of contact fatigue failure.9 reasons for Timken bearing sound
  • Wear failure
  • Wear failure refers to the failure caused by the continuous wear of the metal on the working surface caused by the relative sliding friction between the surfaces. Continuous wear will cause IKO bearing parts to be gradually damaged, and eventually lead to the loss of dimensional accuracy of IKO bearing and other related problems. Wear may affect the change of shape, the increase of fit clearance and the change of working surface morphology, may affect the lubricant or make it polluted to a certain extent, resulting in the complete loss of lubrication function, so that IKO bearing loses rotation accuracy and even can not operate normally. Wear failure is one of the common failure modes of various bearings. According to the wear form, it can be divided into common abrasive wear and adhesive wear.
  • Abrasive wear refers to the wear caused by the relative movement of the contact surface due to the extrusion of foreign hard particles or hard foreign matters or wear debris on the metal surface between the working surfaces of IKO bearings, which often causes furrow like scratches on the working surfaces of IKO bearings.9 reasons for Timken bearing sound
  •  Hard particles or foreign matters may come from the inside of the host machine or from other adjacent parts of the host system, and are sent into the IKO bearing by the lubricating medium. IKO bearing accuracy error related knowledge. Adhesive wear refers to the uneven stress on the friction surface due to the micro bulge or foreign matter on the friction surface. 9 reasons for Timken bearing sound
  • When the lubrication conditions are seriously deteriorated, the local deformation and friction micro welding of the friction surface are easy to be caused due to the heat generated by local friction.9 reasons for Timken bearing sound
  •  In serious cases, the surface metal may be locally melted, and the force on the contact surface will tear the local friction welding point from the substrate and increase the plastic deformation. This cycle of adhesion tear adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch and severe adhesive wear is called bite.9 reasons for Timken bearing sound
9 reasons for Timken bearing sound

9 reasons for Timken bearing sound

  • Too little grease injection is easy to cause lack of grease or dry friction and affect service life. Excessive grease injection will lead to a large amount of grease leakage, which will not only pollute the environment, but also cause waste. 
  • It can be seen that the amount of grease injected into Timken imported bearing is the less the better on the premise of ensuring the full lubrication of Timken imported bearing.9 reasons for Timken bearing sound
  • Advantages and disadvantages of grease lubrication under normal working conditions, grease lubrication can be used for most Timken imported bearing applications.9 reasons for Timken bearing sound
  • The advantage of grease is that it is easier to retain in Timken imported bearing configuration, especially in applications where the vertical axis or axis is inclined at a certain angle. The grease also has the function of sealing, which can prevent the influence of pollutants, moisture or moisture on Timken imported bearings. 9 reasons for Timken bearing sound
  • However, if there is too much grease, it will lead to the increase of bearing working temperature, especially in the application of high speed. Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing
  • In most cases, the Timken inlet bearing can be completely filled with grease only at the initial stage, while the Timken inlet bearing seat is only filled with an appropriate amount of grease and left with a certain free space. 9 reasons for Timken bearing sound
  • Before fully reaching the working speed, the excess grease must be discharged from the bearing during the running in stage, so that an appropriate amount of grease can be left in the Timken inlet bearing. When the operating temperature drops significantly, it indicates that the grease has run in with the bearing and is evenly distributed in the Timken imported bearing configuration.9 reasons for Timken bearing sound
  • The so-called constant pressure preload is a method of giving appropriate preparatory load to the bearing by using coil spring and Belleville spring. In use, even if the relative position of the bearing changes, the preloading method. In use, even if there is a change in the relative position of the walking out, the preload can be roughly maintained at a certain level.9 reasons for Timken bearing sound
  • Preload line diagram of SKF imported bearing after constant pressure preload. The rigidity of preload spring is usually very small compared with that of bearing. Therefore, the displacement straight line of spring is approximately parallel to the horizontal axis. Therefore, the rigidity of single bearing with constant pressure preload is the same as that of pre applied preload.9 reasons for Timken bearing sound
  • The rigidity of the single bearing with axial load is roughly the same. Comparison of rigidity between SKF imported bearing and bearing monomer after positioning preload and constant pressure preload.9 reasons for Timken bearing sound
  • According to the rigidity comparison of preloading methods, the comparison of positioning preload and constant pressure preload is as follows. After fag bearing installation, in order to check whether the installation is correct, operation inspection shall be carried out. Small machinery can be rotated by hand to confirm whether it rotates smoothly. 9 reasons for Timken bearing sound
  • The inspection items include poor operation caused by foreign matters, scars and indentation, unstable torque caused by poor installation and poor processing of mounting base, excessive torque caused by too small clearance, installation error and sealing friction, etc. If there is no abnormality, the power operation can be startedInstallation method and precautions of IKO bearingInstallation method and precautions of IKO bearing.9 reasons for Timken bearing sound
  • Large machinery cannot rotate manually, so the power shall be cut off immediately after no-load start, and the machinery idles. Check whether there is vibration, noise, contact of rotating parts, etc. after confirming that there is no abnormality, enter the power operation.9 reasons for Timken bearing sound
  • 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.9 reasons for Timken bearing sound
  • 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.9 reasons for Timken bearing sound
  •  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.9 reasons for Timken bearing sound
  • 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. 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.Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing
  • 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.Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing
  • 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.
  • 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)
  • 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.Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing
  • 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.9 reasons for Timken bearing sound
  • 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.9 reasons for Timken bearing sound
  •  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.Installation method and precautions of IKO bearingInstallation method and precautions of IKO bearing
  • 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.9 reasons for Timken bearing sound
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