Selection and use of fag bearings
Selection and use of fag bearings
2022年5月16日
Influence of bearing load on accuracy
Influence of bearing load on accuracy
2022年5月18日

Maintenance measures to prevent bearing failure

The noise of small bearings is relatively lower than bearing failure

  • If you hear the noise from the bearing, first of all, it is important to find the location where the noise occurs. There are many moving parts that may produce noise, or some rotating parts may come into contact with non rotating parts. If the noise in the bearing is confirmed, it may be damaged and need to be replaced.
  • Since the working conditions leading to the failure of both sides of the front are similar, even if only one is broken, it is recommended to replace it in pairs.Maintenance measures to prevent bearing failure
  • Bearings are sensitive, and in any case, correct methods and appropriate tools need to be used. During storage, transportation and installation, the components of the bearing shall not be damaged. A large pressure is required to press in, so a special tool is required. Be sure to refer to the instructions.Maintenance measures to prevent bearing failure
  • It should be installed in a clean and tidy environment. The entry of small particles will also shorten the service life of the bearing. It is very important to keep a clean environment during replacement. It is not allowed to knock with a hammer. Be careful not to fall on the ground (or similar improper handling). Check the condition of the shaft and seat before installation. Even slight wear will lead to poor fit and damage.Maintenance measures to prevent bearing failure
  • Do not attempt to disassemble the bearing or adjust the sealing ring, otherwise the sealing ring will be damaged and water or dust will enter. Even the sealing ring and the raceway of the inner ring are damaged.Maintenance measures to prevent bearing failure
  • There is a magnetic thrust ring in the sealing ring equipped with ABS, which can not be impacted, impacted or collided with other magnetic fields. Take them out of the packing box before installation and keep them away from the magnetic field, such as the motor or electric tool used.Maintenance measures to prevent bearing failure
  • Many bearings are sealed and do not need to be greased throughout their life. Other unsealed, such as double row tapered rollers, must be lubricated with grease during installation. Due to the different size of the inner cavity, it is difficult to determine how much grease to add. If there is too much grease, the excess grease will seep out when the bearing rotates. General experience: during installation, the total amount of grease should account for 50% of the clearance.Maintenance measures to prevent bearing failure
  • The lubrication purpose of rolling bearing is to reduce the internal friction and wear of bearing and prevent burning and sticking. Its lubrication effect is as follows:Maintenance measures to prevent bearing failure
  • Reduce friction and wear:Maintenance measures to prevent bearing failure
  • Prevent metal contact and reduce friction and wear at the contact parts of the ring, rolling element and retainer constituting the bearing.Maintenance measures to prevent bearing failure
  • Extended fatigue life:
  • The rolling fatigue life of the bearing is prolonged when the rolling contact surface is well lubricated during rotation.
  • On the contrary, the oil viscosity is low and the lubricating oil film thickness is not good. Is shortened.
  • Discharge friction heat and cooling:Maintenance measures to prevent bearing failure
  • Circulating oil supply method can use oil to discharge the heat generated by friction or the heat and cooling transmitted from the outside. Prevent the bearing from overheating and the lubricating oil from aging.
  • In addition, bearing lubrication can also prevent foreign matters from invading the interior of the bearing, or prevent rust, corrosion, etc.Maintenance measures to prevent bearing failure
  • clean:
  • When removing the bearing for inspection, first make appearance records by photography and other methods. In addition. Confirm the amount of remaining lubricant and sample the lubricant. Then clean the bearing.Maintenance measures to prevent bearing failure
  • The cleaning of bearings is divided into rough cleaning and fine cleaning, and a metal grid can be placed at the bottom of the container.Maintenance measures to prevent bearing failure
  • B. during rough cleaning, remove grease or adhesion with a brush in the oil. At this time, if the bearing is rotated in oil. Note that the rolling surface will be damaged by foreign matters.Maintenance measures to prevent bearing failure
  • C. during fine cleaning, rotate the bearing slowly in oil. It must be carried out carefully.Maintenance measures to prevent bearing failure
  • The cleaning agent usually used is neutral water-free diesel or kerosene. Warm lye is sometimes used as needed. No matter what kind of cleaning agent you use, always filter it and keep it clean. After cleaning, coat the bearing with antirust oil or grease immediately
  • Rolling bearing with low noise requirements
  • In the production of standard IKO bearings, some single row radial ball bearings and short cylindrical roller bearings have low-noise varieties for motor bearings. The inner diameter of ball bearing φ 2.5mm to φ There are several varieties of 60mm with three suffixes of ZL, Z2 and Z3, which correspond to three different low-noise requirements respectively. Among the roller bearings, there are eight models from n309 to n322, which are also manufactured according to the low-noise standard
  • These IKO bearings can be fully applicable to other machines with low noise requirements, and the price is cheap. If the type and size can meet the requirements, try to use these two types of low noise bearings.Maintenance measures to prevent bearing failure
  • When the above two types of low noise bearings cannot be used, IKO bearings with relatively low noise can be used. The specific comparison basis is as follows:Maintenance measures to prevent bearing failure
  • The noise of ball bearing is lower than that of roller bearing, and the (friction) noise of bearing with less sliding is lower than that of bearing with more sliding;Maintenance measures to prevent bearing failure
  • The noise of IKO bearing with solid cage is relatively lower than that of bearing with stamping cage; The noise of bearings with plastic cages is lower than that of bearings with the above two cages; If there are many balls, the outer ring is thick and the noise is small;Maintenance measures to prevent bearing failure
  • The noise of bearings with high precision, especially those with higher rolling element precision, is relatively lower than that of bearings with low precision;Maintenance measures to prevent bearing failure
  • The main causes of IKO bearing fracture failure are defect and overload. When the external load exceeds the material strength limit and causes the part to break, it is called overload fracture. The main cause of overload is the sudden failure or improper installation of the host. Maintenance measures to prevent bearing failure
  • Defects such as microcracks, shrinkage cavities, bubbles, large foreign objects, overheated tissue and local burns of bearing parts will also cause fracture at the defect during impact overload or violent vibration, which is called defect fracture.Maintenance measures to prevent bearing failure
  •  It should be pointed out that in the manufacturing process of bearings, the presence of the above defects can be correctly analyzed by instruments in the factory re inspection of raw materials, quality control of forging and heat treatment, and processing process control, and the control must be strengthened in the future. But generally speaking, most of the bearing fracture failures are overload failures. Maintenance measures to prevent bearing failure
  • Timken bearing is a precision part, so it is required to be quite cautious in use, that is, it uses a high-performance thrust ball bearing. If it is not used properly, it can not achieve the expected performance effect, and it is easy to damage the bearing. Therefore, the following matters should be paid attention to when using bearings:Maintenance measures to prevent bearing failure
  • Even if the invisible smile dust enters the bearing, it will increase the wear, vibration and noise of the bearing.Maintenance measures to prevent bearing failure
  • It is not allowed to punch with force, directly knock the bearing with a hammer, and transfer pressure through the rolling element. We hope to unpack Timken bearings during installation. During general grease lubrication, the bearing is not cleaned, but directly filled with grease. Maintenance measures to prevent bearing failure
  • In case of oil lubrication, it is generally not necessary to clean. However, bearings for instrument or high-speed use should be cleaned with clean oil to remove the rust inhibitor coated on the bearings. Bearings with rust inhibitor removed are easy to rust, so they cannot be placed at will.
Maintenance measures to prevent bearing failure

Bearing failure with relatively low noise are used

  • Timken bearing will make some noise after running for a period of time, which is normal, but if the sound is very noisy and continuous, it indicates that the problem of noise has occurred in the bearing. Why does the bearing make noise?Maintenance measures to prevent bearing failure
  • Any one of the inner and outer rings and rolling elements has peeling; The raceway surface and rolling element are rusted and scarred; The raceway surface, retaining edge and rolling element are significantly jammed; There are obvious indentation and indentation on the rolling surface and rolling body; Any one of the inner and outer rings, rolling elements and confrontation frame has cracks and fragments; Maintenance measures to prevent bearing failure
  • Overheating and discoloration; The sealing ring and dust cover of grease sealed bearing are seriously damaged; Serious wear of cage or loose rivets; Maintenance measures to prevent bearing failure
  • There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring, etc. The matching of rolling bearings should make the installation and disassembly of bearings simple and convenient, and try to save time, labor and expenditure;Maintenance measures to prevent bearing failure
  • In order to reduce the deformation degree of Timken bearing ring and give full play to the bearing capacity of the bearing, the bearing ring is well supported and stressed evenly;Maintenance measures to prevent bearing failure
  • It must adapt to the axial position and have the ability to swim within a certain range, so the free end bearing must adapt to the length change of the shaft and Timken bearing seat hole;Maintenance measures to prevent bearing failure
  • In addition, the ferrule cannot slide along the tangent direction in its mating surface, so as not to damage the mating surface;Maintenance measures to prevent bearing failure
  • Grease is used to lubricate bearings. Of course, the more the better. In fact, it is not. It is unnecessary to add too much grease in the bearing, but it will increase friction and raise the temperature. The lubricating film of the bearing will be damaged if it is greased too little. Therefore, it is important to determine the appropriate amount of grease in Timken bearings. Refer to the following principles for the general grease filling amount in the outer spherical ball bearing with seat: bearing failure
  • The viscosity of lubricating oil is the basic factor for the formation of lubricating oil film. Under the working conditions of medium speed, medium load and low temperature, medium viscosity lubricating oil shall be selected. Under the working conditions of heavy load, low speed and high temperature, high viscosity lubricating oil or lubricating oil with extreme pressure anti-wear agent shall be selected. Low viscosity lubricating oil shall be selected under low load, high speed and low temperature.Maintenance measures to prevent bearing failure
  • Under the conditions of wide temperature range, light load, high speed and other special requirements, synthetic lubricating oil shall be selected. bearing failure
  • Taking internal combustion engine oil as an example, select appropriate viscosity and high viscosity index to make the oil not only have enough high-temperature viscosity to ensure the lubrication and sealing of the engine during operation, but also have enough low viscosity at low temperature to ensure low-temperature starting performance. The choice of viscosity is usually based on the temperature conditions, and the factors such as load, speed or engine wear should be considered at the same time. bearing failure.Maintenance measures to prevent bearing failure

Saving the inner and outer diameter of bearing ring

  • Installation: whether Timken bearing is installed correctly affects accuracy, service life and performance. Therefore, the design and assembly department should fully study the installation of bearings. Therefore, when installing the bearing, we should strictly follow the installation steps of the bearing to prevent damage to the bearing.Maintenance measures to prevent bearing failure
  • Alignment and alignment: after Timken bearing is installed, if alignment and alignment are not carried out carefully, the bearing may suffer additional load, friction and vibration. These may accelerate fatigue and reduce the service life of bearings, and may damage the service life of other machine parts. In addition, increased vibration and friction may greatly increase energy consumption and the risk of premature failure.Maintenance measures to prevent bearing failure
  • Monitoring: during use, the basic external conditions of Timken bearing operation shall be monitored frequently, such as temperature, vibration and noise measurement. These regular inspections will identify potential problems as soon as possible, prevent unexpected machine stoppage, realize the production plan and improve the productivity and efficiency of the plant.Maintenance measures to prevent bearing failure
  • Re lubrication: in the process of operation, the bearing is required to have correct re lubrication and perfect its performance. The methods of bearing lubrication are divided into grease lubrication and oil lubrication. In order to make Timken bearing function well, we must first choose the lubrication method suitable for use conditions and purposes. If only lubrication is considered, the lubricity of oil lubrication is dominant.Maintenance measures to prevent bearing failure
  • Disassembly: Timken bearing should be replaced when it will reach its final service life. Although Timken bearings can no longer be used, correctly removing the original bearings and replacing new bearings in time can play a good role in prolonging the service life of new bearings.Maintenance measures to prevent bearing failure
  • Firstly, the size of each defect (asymmetric type) of the part is accurately measured, and the small grinding amount (the grinding amount when the size deviation of the finished product) m is calculated. Then, during grinding, the center of the part is offset (offset in the direction of increasing the grinding amount at the defect), and the large offset is m / 2, that is, the grinding amount is relatively increased at the defect, focusing on grinding.Maintenance measures to prevent bearing failure
  • Rescue of inner and outer raceways of ferrule
  • The grinding design basis of bearing ring is inner diameter or outer diameter, that is, grinding the inner (outer) diameter first and then the raceway. Taking the inner race as an example, if the inner raceway has asymmetric defects, it is necessary to accurately measure the inner diameter of the part, and calculate the large grinding amount m and the large grinding amount M1 at the defect of the inner raceway. Maintenance measures to prevent bearing failure
  • When M1 < m, the inner ring center offset is required when grinding the inner diameter, and the large offset is M1 / 2, that is, when machining the inner diameter, the grinding amount is relatively increased in advance for the defect of the inner raceway, and then when grinding the inner raceway, the defect will be mainly ground and the waste products will be saved. When M1 ≥ m, it cannot be removed by normal grinding, and the method described in section (1) can be adopted according to the situation.Maintenance measures to prevent bearing failure
  • The center offset grinding is carried out on the premise of ensuring the hardness of parts and the depth of carburized layer. The total offset cannot be completed in one offset grinding. It is generally divided into several times of grinding, that is, through the repeated process of offset trial grinding – Measurement – adjustment of offset – re grinding. Maintenance measures to prevent bearing failure
  • After the defects are ground off, re align and correct the ovality through normal grinding. The efficiency of this method is low, and the operator is required to have a high technical level. However, this method has a high success rate in single machine and single piece production and does not delay the production progress. After several years of practice, the effect is good.Maintenance measures to prevent bearing failure
  • Whether the outer packaging is clear: generally, the brands of the main factory have their own special designers to design the outer packaging, and arrange the factories with qualified production conditions for production. Therefore, the packaging is very clear from line to color block ­, Unambiguous.
  • Whether the steel seal words are clear: brand words, labels, etc. will be printed on the bearing body. The font is very small, but most of the products produced by the original factory use steel printing technology, and they are pressed before overheating treatment. 
  • Therefore, although the font is small, it is concave ­ Deep, very clear. The font of counterfeit products is not only fuzzy, but also floating on the surface due to the rough printing technology. Some of them can even be easily erased by hand.
  • Whether there is any noise: hold the bearing body sleeve with your left hand, and rotate the sleeve with your right hand to listen for any noise. Due to the backward production conditions of most counterfeit products and complete manual workshop operation, sand will inevitably be mixed in the production process ­ A kind of impurity is hidden in the bearing body, so it will make a noise when rotating. This is a big difference from the factory brand that strictly implements production standards and operates with machines.
  • Whether there is muddy oil on the surface: this should be paid special attention when purchasing fag bearings. As the current domestic antirust technology is not particularly good, it is easy to leave thick oil stains when antirust the bearing body and stick them on your hand ­ It is viscous and thick, and there is almost no trace of antirust oil on the foreign original fag bearing. However, a particularly careful expert said that fag bearing smells like a smell. It must be antirust oil, but it can’t be seen.
  • Whether the chamfering is uniform: the so-called bearing chamfering, that is, the junction of horizontal and vertical surfaces. Due to the limitation of production technology, the fake bearing is not handled satisfactorily in these corners.
  • 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 fag bearing parts, followed by the shape error and surface roughness of the inner ring and outer ring channels, and then the bearing cleanliness and lubricant quality.
  • Operating conditions, such as installation conditions, rotating speed, axial load direction, quantity, etc.
  • Bearing fatigue failure is a surface form of failure, which is mainly manifested in the initiation, propagation and fracture process of fatigue crack, and the long-term impact of load failure under alternation. Cracks are in two ways:
  • First of all: from the surface, this is the external load caused by the plastic deformation of the working surface and the periodic change of the contact stress of the strain hardened surface during the rolling contact process of fag bearing, and finally the formation of the surface crack between the two from the developing inner surface of the small crack. Due to the lubricant on the working surface and the open force, the crack is severely hit on the wall and forced to move forward;
  • Second: from the surface layer, under repeated pressure, the contact of the surface will initially produce cracks at a certain depth at the place where the surface is exposed, and from the angle along the surface direction to a certain depth, from behind the surface of the contact surface and beyond the surface, and finally form corrosion stripping, leaving a horse pit.