Our customers always have some improper use methods when using all kinds of NTN bearing grease. Today, we will explain the use principle and function of grease in the bearing.
1. Operating principle of grease
Everyone knows that liquid grease is a very thick solution. This kind of grease is composed of network soap fiber. Its structure determines that it can absorb a large amount of lubricating oil and make it work normally. But as you can imagine, if a sponge is squeezed, water will flow out.
The grease will also discharge the lubricating oil due to extrusion, but the grease in NTN bearing is rarely directly squeezed and discharged, because when a newly lubricated imported bearing is running in, the grease moves in the internal space of the bearing. Its main working principle is “temperature”.
2. Practical function of grease
The main reason to drain the grease to the sliding surface is the temperature rise of the grease around the NTN bearing. When the bearing starts running, under normal working conditions, the grease will reach the sliding friction surface. As the temperature rises, lubrication Grease In Ntn Bearing begins to take effect.
Advantages of grease lubrication for NTN imported bearings:
1) Individual bearing points must be refueled frequently by hand. If the grease is changed, it will not Grease In Ntn Bearing only save trouble, but also avoid accidents caused by lack of oil.
2) The grease itself has a sealing effect, which allows the mechanism with low sealing Grease In Ntn Bearing degree to be used to simplify the design.
3) Experience has proved that in a certain speed range (n < 20000 R / min or DN < 20000 mm. R / min), lithium grease lubrication has lower temperature rise and longer bearing life than oil dropping method.
2. Theoretical basis of NTN imported bearing lubrication: the lubrication mechanism of the Grease In Ntn Bearing bearing belongs to the theory of elastic fluid hydrodynamic lubrication.
3. Relationship between NTN bearing failure type and lubrication: most failure causes are damage caused by faulty assembly and poor sealing. A few failures are caused by wear, gluing, corrosion and overheating caused by lack or excess of lubricant or unqualified quality.
4. Basic characteristics of Grease In Ntn Bearing lubricating grease and general criteria for selecting lubricating grease:
When selecting lubricating grease, it is necessary to select the lubricating grease suitable for the service conditions (temperature, speed, load and environment, etc.), which are related to the basic characteristics of lubricating grease, and the basic characteristics of lubricating grease depend on the type of thickener and base oil.
Use factors mainly refer to whether the installation, Grease In Ntn Bearing 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. 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 Grease In Ntn Bearing service life early. The internal factors mainly refer to the three factors that determine the bearing quality, such as structural design, manufacturing process and material quality.
The metallurgical quality of imported bearing materials was Grease In Ntn Bearing once the main factor affecting the early failure of rolling bearings. With the progress of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved.
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.
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.
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.
The main task of Koyo bearing service life 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.
In general, the filling amount of lubricating grease in Koyo bearing always exceeds the actual demand for direct lubrication. It is on the holder and in the cavity of the bearing cover, and forms a contour on the periphery of the rolling element. During this process, the bearing temperature rises rapidly due to the resistance of excess grease.
Although most of the excess grease is squeezed out at the Grease In Ntn Bearing initial stage of operation, and the grease squeezed in the accessories of the raceway may still be brought into the raceway by the rotating rolling element.
In the initial stage of bearing operation, most of the grease is quickly squeezed out of the raceway (less than one minute), and the accumulated grease is discharged in a small amount while circulating with the rotating body of the bearing.
At this time, the bearing Wendu continues to rise until all the excess bearing grease is discharged, which can be called the running in stage of grease. According to the quality and filling amount of grease in the bearing structure, this period may last for more than ten minutes or even several hours.
After the remaining Koyo bearing grease is completely discharged, the remaining small amount of grease forms a thin layer of grease film on the mutual contact surface of the rolling element, raceway and cage through the action of a wedge, so as to enter the normal operation stage of the bearing.
At this time, the temperature gradually decreases and reaches equilibrium. In other words, the long-term lubrication mainly depends on this layer of grease film.
In addition, it also plays a role in the long-term operation of the lubricating oil inlet and outlet part of the rolling frame, and it also plays a role in the long-term operation of the lubricating oil inlet and outlet part of the rolling frame.
Different bearing greases form different contours in the bearing. The contour must be formed. It is quite draft, the running in time is short, and the bearing temperature is low and stable in long-term operation. This is an ideal grease, so it is particularly important for the channelization of the grease.
Some so-called vortex type greases are not the case. They are not easy to form a contour. Even if the contour is formed, they are easy to collapse.
At this time, the excess grease returning to the raceway repeatedly is in the condition of forced stirring for a long time. The torque of Koyo bearing is large, the temperature is high, and it is unbalanced. It may also produce noise, and the grease is easy to deteriorate and lose.