Fault inspection of NSK bearing in operation
Fault inspection of NSK bearings operation
2022年5月13日
Inspection of vibration fault of punching outer ring needle roller bearing during operation
Inspection of vibration fault of punching outer ring needle roller bearing during operation
2022年5月14日

Analysis of distinguishing the burn fault of Koyo bearing

Noise and vibration are random;Analysis of distinguishing the burn fault of Koyo bearing

  • The so-called burn damage state of the bearing refers to the sharp heating of the raceway wheel, rolling element and cage of Koyo bearing during rotation until discoloration, softening, deposition and damage.Analysis of distinguishing the burn fault of Koyo bearing
  • The main reason for the burn of Koyo bearing is that the lubrication of the bearing is poor, and irregular lubricant may be used, or too much or too little lubricant is incorrect.Analysis of distinguishing the burn fault of Koyo bearing
  • The contamination degree of lubricant can be judged by sampling it. The comparison is applicable to Koyo bearings or large bearings that cannot be close to observation.Analysis of distinguishing the burn fault of Koyo bearing
  • The sound of Koyo bearing can be clearly heard by sticking the listener or sound stick on the shell. Rich experience is required for sound recognition. Therefore, it must be fully trained to recognize bearing sound and non bearing sound.Analysis of distinguishing the burn fault of Koyo bearing
  • There is a small convex metal surface between the journal and the Koyo 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 locally burned. This fault is often caused by too tight fit between journal and Koyo bearing; Insufficient lubricating oil pressure is also easy to burn Koyo bearings.Analysis of distinguishing the burn fault of Koyo bearing
  • Mechanical damage of bearing refers to different degrees of groove marks 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 Koyo bearing is that it is difficult to form oil film on the surface of Koyo bearing or the oil film is seriously damaged.
  • The vibration frequency is above 1kHz;Analysis of distinguishing the burn fault of Koyo bearing
  • No matter how the rotating speed changes, the main frequency of noise is almost unchanged, while the sound pressure level increases with the increase of rotating speed;Analysis of distinguishing the burn fault of Koyo bearing
  • When the radial clearance increases, the sound pressure level increases sharply;Analysis of distinguishing the burn fault of Koyo bearing
  • When the rigidity of the bearing pedestal increases, the lower the total sound pressure level is, and even if the speed increases, the total sound pressure level does not increase much;Analysis of distinguishing the burn fault of Koyo bearing
  • The higher the viscosity of lubricant, the lower the sound pressure level, but for grease lubrication, its viscosity and the shape and size of soap fiber can affect the noise value.Analysis of distinguishing the burn fault of Koyo bearing
  • The sound generation source of raceway is caused by the natural vibration of ferrule after being loaded. The elastic contact between the ferrule and the rolling body constitutes a nonlinear vibration system. When the lubrication or machining accuracy is not high, the natural vibration related to this elastic feature will be excited, and when it is transmitted to the air, it will become noise. 
  • As we all know, even if the contemporary superb manufacturing technology is used to process Koyo bearing parts, there will always be small geometric errors in varying degrees on the working surface, resulting in small fluctuations between the raceway and the rolling body and exciting the natural vibration of the vibration system.Analysis of distinguishing the burn fault of Koyo bearing
  • Generally, the corrosion area of Koyo bearing alloy is impure lubricating oil. 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. Analysis of distinguishing the burn fault of Koyo bearing
  • The main reasons for the corrosion of Koyo bearing alloy are improper selection of lubricating oil, poor corrosion resistance of Koyo bearing materials, or rough engine operation and high temperature.Analysis of distinguishing the burn fault of Koyo bearing
  • The anti friction Koyo bearings in all bearings basically contain two hardened steel rings, multiple hardened balls or rollers, and a separating roller or roller separating frame or cage. These types are divided into many types in use. Some types, such as needle column bearings, may have no inner ring and the roller moves directly on the hardened shaft.Analysis of distinguishing the burn fault of Koyo bearing
  • In practice, it is necessary to use more than the recommended amount of grease. When the required torque is low, the lubrication of Koyo bearings can be completed with very little grease. When the speed is very low and the bearing is exposed to dust or moisture, the bearing may be almost filled. Analysis of distinguishing the burn fault of Koyo bearing
  • Koyo bearings usually require more frequent lubrication than normal under high speed and high temperature conditions. What are the main factors affecting bearing vibration?Analysis of distinguishing the burn fault of Koyo bearing
  • The vibration system composed of stiffness, flexibility, mass and damping determined by the design parameters of bearing structure will produce vibration suitable for its mechanics under operating conditions.Analysis of distinguishing the burn fault of Koyo bearing
  • Vibration caused by deviation in manufacturing and processing. The smaller the deviation is, the smaller the vibration is. The roundness, waviness and surface roughness of the steel ball surface are the main factors affecting the bearing vibration. What are the main factors?Analysis of distinguishing the burn fault of Koyo bearing
  • The vibration system composed of stiffness, flexibility, mass and damping determined by the design parameters of bearing structure will produce vibration suitable for its mechanics under operating conditions.Analysis of distinguishing the burn fault of Koyo bearing
  • Vibration caused by deviation in manufacturing and processing. The smaller the deviation is, the smaller the vibration is. The roundness, waviness and surface roughness of the steel ball surface are the factors that have a great impact on the vibration of each bearing part, followed by the shape error and surface roughness of the inner ring and outer ring channels, and then the bearing cleanliness and lubricant quality.Analysis of distinguishing the burn fault of Koyo bearing
  • Operating conditions, such as installation conditions, rotating speed, axial load direction, quantity, etc. Generally, rolling bearings are used. Due to less friction and less damage, the service life of rolling bearings can reach fatigue life. Analysis of distinguishing the burn fault of Koyo bearing
  • However, if an accident occurs during use, it may also cause early damage and cannot be used. Generally, it is not because the fatigue life is reached that it can not be used. We become early damage, or it is directly called service failure or accident. It usually occurs in the installation, use and lubrication of rolling bearings.Analysis of distinguishing the burn fault of Koyo bearing
  • Structure of rolling bearing; In general, different parts have different structures, and their processing technology is different. If mismatched rolling bearings are used on different parts, it must be easy to damage the rolling shaft.Analysis of distinguishing the burn fault of Koyo bearing
  • Improve processing technology; The lower quenching heating temperature is used in the heat treatment process of rolling bearing, and the holding time is appropriately prolonged, which can improve the alloy concentration of bearing and enhance the impact toughness of bearing.Analysis of distinguishing the burn fault of Koyo bearing
  •  Improve processing monitoring means; Promote the improvement of processing quality. For example, improve the monitoring of the curvature position of the flow channel, improve the overall performance of the automobile bearing after assembly, and improve the working condition of the rolling bearing. Analysis of distinguishing the burn fault of Koyo bearing
  • Generally, in order to judge whether the disassembled bearing is normal and can be used, it should be checked after the bearing is cleaned. Check the state of raceway surface, rolling surface and mating surface, the wear of cage, the increase of bearing clearance and the damage of irrelevant dimensional accuracy, which are abnormal. 
  • For non separable small ball bearings, support the inner ring horizontally with one hand and rotate the outer ring to confirm whether it is smooth.Analysis of distinguishing the burn fault of Koyo bearing
  •  Tapered roller bearings and other separable bearings can inspect the raceway surfaces of rolling elements and outer rings respectively. Since large bearings cannot be rotated by hand, pay attention to the appearance of rolling elements, raceway surfaces, cages, edge retaining surfaces, etc. the higher the importance of bearings, the more careful the inspection is.Analysis of distinguishing the burn fault of Koyo bearing
  • Secondly, the cleaned bearing needs to be wiped dry with rags, and then soaked in antirust oil. In this process, the bearing shall be completely contacted with the antirust oil and the bearing shall be rotated continuously, so that the oil film formed by the antirust oil can cover the surface of the bearing, so as to achieve the purpose of antirust.Analysis of distinguishing the burn fault of Koyo bearing
  • Then it is necessary to apply butter evenly on the surface of the bearing, including inner and outer rings, wheels and cages. And the bearing is rotated while wiping, so that the butter can really enter the bearing and play a full role in lubrication.Analysis of distinguishing the burn fault of Koyo bearing
Analysis of distinguishing the burn fault of Koyo bearing

Analysis of distinguishing the burn fault of Koyo bearing

  • Generally, in order to judge whether the disassembled bearing is normal and can be used, it should be checked after the bearing is cleaned. Check the state of raceway surface, rolling surface and mating surface, the wear of cage, the increase of bearing clearance and the damage of irrelevant dimensional accuracy, which are abnormal. For non separable small ball bearings, support the inner ring horizontally with one hand and rotate the outer ring to confirm whether it is smooth.Analysis of distinguishing the burn fault of Koyo bearing
  •  Tapered roller bearings and other separable bearings can inspect the raceway surfaces of rolling elements and outer rings respectively. Since large bearings cannot be rotated by hand, pay attention to the appearance of rolling elements, raceway surfaces, cages, edge retaining surfaces, etc. the higher the importance of bearings, the more careful the inspection is.Analysis of distinguishing the burn fault of Koyo bearing

Secondly, the Koyo bearing needs to be wiped dry with rags

  • and then soaked in antirust oil. In this process, the bearing shall be completely contacted with the antirust oil and the bearing shall be rotated continuously, so that the oil film formed by the antirust oil can cover the surface of the bearing, so as to achieve the purpose of antirust.
  • Then it is necessary to apply butter evenly on the surface of the bearing, including inner and outer rings, wheels and cages. And the bearing is rotated while wiping, so that the butter can really enter the bearing and play a full role in lubrication. Analysis of distinguishing the burn fault of Koyo bearing
  • There may be many factors affecting the service life of linear sliding bearings. The factors that may lead to and the internal friction sound have been further explained in the operating instructions. The main factors used for adjustment are installation, use and maintenance, maintenance and repair, which meet the technical requirements. Analysis of distinguishing the burn fault of Koyo bearing
  • According to the technical requirements for the installation, use, maintenance and maintenance of needle roller bearing, the contact load, speed and lubrication status of the operating bearing are monitored and checked. The direct cause of abnormality is found and adjusted back to normal.Analysis of distinguishing the burn fault of Koyo bearing
  • Installation conditions, one of the factors used for needle roller bearing is the load-bearing force that often causes the state change between various parts of the incorrect installation package, the primary factor of abnormal working temperature of linear sliding bearing, vibration, noise and gradual progress, and the quality of raw materials is improved. The proportion of raw material quality factor in bearing fault analysis has decreased significantly, but it is still one of the main factors of bearing failure.Analysis of distinguishing the burn fault of Koyo bearing
  • Whether the selection is appropriate or not is still the fault analysis of linear sliding bearing. Needle roller bearing manufacturing will be adjusted and restored to normal through forging, heat treatment, turning and lubrication conditions to monitor and check the direct causes of abnormalities. Analysis of distinguishing the burn fault of Koyo bearing
  • The installation condition is one of the factors for using the bearing. It is the primary factor of the bearing capacity that often causes the state change between various parts of the incorrect installation package. 

The self-lubricating fault of Koyo bearing

  • In the abnormal operation state and the early termination of the inner life, the main factors refer to the structural design, high-quality manufacturing technology and materials. There are three factors that determine the quality of the bearing.Analysis of distinguishing the burn fault of Koyo bearing
  • The self-lubricating bearing is a composite self-lubricating sliding block made of ordered and appropriately sized holes developed on the metal friction surface of the bearing matrix and embedded with molybdenum disulfide and graphite. Analysis of distinguishing the burn fault of Koyo bearing
  • It is embedded on the metal sleeve. The friction area of solid lubricant is 25-65%. The solid self-lubricating slider can work normally under the high temperature of 280 ℃. However, due to its low mechanical strength, weak bearing capacity and easy deformation, embedding it in the metal hole and groove can inhibit this disadvantage, forming a metal part for bearing and a self-lubricating sliding block for lubrication. Analysis of distinguishing the burn fault of Koyo bearing
  • The lubrication mechanism of this self-lubricating bearing is that during the sliding friction between the shaft and the sleeve, part of the molecules of the self-lubricating material are transferred to the metal surface of the shaft, the micro uneven surface is filled, and a relatively stable solid lubrication film is formed, resulting in the friction between the solid lubrication films and preventing the adhesive wear between the shaft and the sleeve. 
  • This reasonable combination combines the complementary advantages of copper alloy and non-metallic wear reducing materials. It is especially suitable for the range of motion in oil-free, high temperature, high load, low speed, anti pollution, anti-corrosion and strong radiation environment, as well as the special working conditions under which lubricating oil cannot be added due to the infiltration of water or other solutions.
  • The area ratio of self-lubricating slider to the surface area of self-lubricating slider is related to the running speed and bearing strength, and the running speed is low; With high bearing strength, the area occupied by metal should be larger.
  • The bearing shall be cleaned with gasoline or kerosene before installation, and used after drying, and good lubrication shall be ensured. Double row deep groove ball bearings are generally lubricated with grease or oil. When grease lubrication is used, the grease with excellent functions such as no impurities, oxidation resistance, rust prevention and extreme pressure shall be selected. 
  • The filling amount of lubricating grease is 30% – 60% of the volume of bearing and bearing box, which should not be too much. The double row deep groove ball bearing with sealing structure has been filled with grease. Users can use it directly and can’t clean it again.
  • When installing the bearing, the bearing must apply equal pressure on the circumference of the ferrule end face to press the ferrule in. It is not allowed to directly knock the bearing end face with hammers and other tools to avoid damaging the bearing. 
  • When the interference is small, press the end face of the bearing ring with the sleeve at room temperature, knock the sleeve with a hammer, and press the ring evenly through the sleeve. If installed in large quantities, hydraulic press can be used. When pressing in, ensure that the end face of the outer ring and the end face of the shell shoulder, and the end face of the inner ring and the end face of the shaft shoulder are pressed tightly without clearance.
  • Measure the size of the shaft and bearing seat hole to determine the matching accuracy of the bearing. The matching requirements are as follows: the inner ring and the shaft adopt interference fit, and the interference amount is 0 ~ + 4 μ M (0 under light load and high precision); Analysis of distinguishing the burn fault of Koyo bearing
  • Clearance fit is adopted between the outer ring and the bearing seat hole, and the clearance is 0 ~ + 6 μ M (but when the angular contact ball bearing is used for the bearing at the free end, the clearance can also be increased); 
  • The roundness error between shaft and seat hole surface is 2 μ M below, the end face parallelism of spacer used for double row deep groove ball bearing is 2 μ M below, the runout of the inner end face and outer end face of the shaft shoulder is 2 μ Below m; The runout of the shoulder of the bearing seat hole to the axis is within 4 μ Below m; The runout of the inner end of the front cover of the main shaft facing the axis is within 4 μ Below M.
  • Installation of fixed end front bearing on the shaft: thoroughly clean the double row deep groove ball bearing with clean cleaning kerosene. For grease lubrication, first inject the organic solvent containing 3% ~ 5% grease into the bearing for degreasing and cleaning, and then fill the quantitative grease into the bearing with an oil gun (accounting for 10% ~ 15% of the bearing space volume); 
  • Heat the bearing to raise the temperature by 20 ~ 30 ℃, and install the bearing into the shaft end with an oil press; Press the set sleeve on the shaft and press the bearing end face with appropriate pressure to make it axially positioned; 
  • Roll the belt of the spring scale on the outer ring of the bearing and check whether the specified preload changes greatly by measuring the starting torque (even if the double row deep groove ball bearing is correct, the preload may also change due to the deformation of the fit or cage).