FAG needle bearing anti-rust and maintenance method

In order to make the FAG bearing parts quenched and tempered, the surface has a large compressive stress, and a carburizing or nitriding atmosphere may be introduced during quenching heating to perform surface carburizing or nitriding for a short time. Since the actual austenite carbon content is not high when the steel is quenched and heated, it is much lower than the equilibrium concentration shown on the phase diagram, so carbon (or nitrogen) can be absorbed. When austenite contains higher carbon or nitrogen, its Ms decreases, and the martensite transformation occurs in the surface layer after quenching than in the inner layer and the core, resulting in a large residual compressive stress. After the GCrl5 steel was heated and quenched by carburizing atmosphere and non-carburizing atmosphere (both low temperature tempering), the contact fatigue test showed that the surface carburizing life was 1.5 times higher than that of non-carburizing. The reason is that the surface of the carburized part has a large residual compressive stress.
The main material factors and control factors affecting the service life of high carbon chromium steel needle roller bearing parts are:
The carbides in the original structure of the steel before quenching are required to be fine and diffuse. High temperature austenitizing at 630 ° C, or 420 ° C high temperature, can also be achieved by wrought waste heat rapid annealing process.
After quenching the GCr15 steel, it is required to obtain a microstructure of cryptocrystalline martensite having an average carbon content of about 0.55%, about 9% of Ar, and about 7% of undissolved carbide in a round state. The quenching heating temperature and time can be utilized to control the microstructure.
After the parts are quenched at low temperature and tempered, a large compressive stress remains on the surface, which contributes to the improvement of fatigue resistance. A treatment process of surface carburizing or nitriding for a short time during quenching heating may be employed, so that a large compressive stress remains on the surface.
Steel for the manufacture of needle bearing parts requires high purity, mainly to reduce the content of O2, N2, P, oxides and phosphides. Electroslag remelting, vacuum smelting and other technical measures can be used to make the material oxygen content ≤ 15PPM.
1. Immersion method: FAG bearings are immersed in anti-rust grease, so that the surface is adhered with a layer of anti-rust grease. The oil film thickness can be achieved by controlling the temperature or viscosity of the rust preventive grease.
2. Brushing method: It is used for needle roller bearings or special-shaped bearings that are not suitable for soaking or spraying. When brushing, it is necessary to pay attention not to produce anti-rust oil accumulation, but also to prevent leakage coating.
3, spray method: some large bearings can not be immersed oil, generally with a pressure of about 0.7Mpa filtered compressed air in the air cleaning place for spraying. The spray method is suitable for solvent-diluted anti-rust oil or thin-layer anti-rust oil, but it must adopt perfect fire and labor protection measures.
The cleanliness of needle bearings has a considerable impact on bearing life. We have conducted special tests for this purpose, and the result is several times or even dozens of times. The higher the cleanliness of FAG bearings, the longer the service life shows that lubricating oils with different cleanliness have a great influence on the life of ball bearings. Therefore, improving the cleanliness of the lubricating oil can prolong the life of the bearing. In addition, if the dirt particles of the lubricating oil are controlled below 10 um, the bearing life is also increased several times.
Impact on vibration The test results of our test center show that the cleanliness seriously affects the vibration level of the bearing, especially the vibration in the high frequency band is more significant. Bearings with high cleanliness have low vibration speed values, especially in the high frequency band.
Effect on noise The effect of dust on the noise in the needle bearing grease has been tested to show that the more dust there is, the greater the noise.
Effect on Lubrication Performance The decrease in the cleanliness of the FAG bearing not only affects the formation of the lubricating oil film, but also causes deterioration of the grease and accelerates its aging, thereby affecting the lubricating performance of the grease.

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FAG thrust ball bearing fault maintenance precautions

Thrust ball bearing fault characteristics show severe faults (usually, such as bearing damage, burns, sand cracking, raceways, beading, etc.) no more than a week old, equipment, capacity is larger, faster, and more Short time interval. Therefore, the actual FAG bearing fault diagnosis, once the fault is discovered, its advanced function, should determine the bearing fault decisively and repair as soon as possible.
  1. Selection and control of shaft and bearing chamber tolerance: After the bearing is pressed into the thrust ball bearing, it should be flexible and unobstructed. If the obvious rotation is not flexible, it means that the size of the shaft is too large and the tolerance is lowered. If the bearing is pressed into the shaft and turned by hand, there is a clear "sand" feeling, which may be that the tolerance of the shaft is too large or the roundness of the shaft is not good. Therefore, it is necessary to control the roundness when controlling the tolerance of the shaft and the bearing chamber. At present, many domestic manufacturers only control the tolerance and do not control the roundness.
  2, the assembly of the bearing: Because the bearing is a high-precision product, such as improper assembly can easily damage the bearing channel, resulting in bearing damage. The FAG bearing should have a special mold during assembly. It can't be beaten at will. When pressing the shaft, it can only be pressed in a small circle. When pressing a large circle, it can only be subjected to a large circle. Air pressure or hydraulic pressure is required for assembly. The upper and lower molds should be outside the horizontal state during press-fit. If tilted, the thrust ball bearing channel will be damaged due to the force, which will cause the bearing to produce a sound.
  3. Prevention of assembly of foreign objects: When the bearing is mounted on the rotor to make dynamic balance, it is easy to enter the iron filings generated during dynamic balancing into the bearing. Therefore, it is better to balance the load before loading the bearing. Some manufacturers have some oil or grease to lubricate the bearing chamber during assembly. However, it is often difficult for the operator to control the amount. If the oil or grease accumulates in the bearing chamber, the FAG bearing rotates. It is easy to enter the inside of the thrust ball bearing along the shaft. It is best not to apply oil or grease to the bearing chamber. If it is not painted, it must be controlled not to accumulate in the bearing chamber.
  4, the prevention of paint rust: paint rust is characterized by multiple seals in the motor, the motor sounds very good when assembled, but after putting some time in the warehouse, the motor noise is very large, the bearing is removed Severe rust. In the past, many manufacturers thought that it was a bearing problem. After our constant publicity, the motor factory has now realized that it is mainly a problem of insulating varnish. This problem is mainly caused by the fact that the acidic substance volatilized by the insulating paint forms a corrosive substance under a certain temperature and humidity, and the bearing of the thrust ball bearing is corroded and causes the bearing to be damaged. The problem can only be achieved by selecting a good insulating varnish and venting it after drying for a while.

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