Self-aligning ball bearing failure cause and operation check work points and daily maintenance skills

After the TIMKEN bearing is installed, check the operation in order to check if the installation is correct. The small machine can be rotated by hand to confirm whether the rotation is smooth. The inspection items have poor operation due to foreign matter, scratches, and indentations. The installation is poor, the torque generated by the mounting is not stable, and the torque is too large due to too small clearance, installation error, and sealing friction. Wait. If there is no abnormality, the power running can be started.

Large machinery cannot be rotated manually, so the power is cut off immediately after the start of the no-load, the machine is idling, and the presence or absence of vibration, noise, and contact of the rotating parts is checked. After confirming that there is no abnormality, the power is turned on.

The power running starts from the no-load low speed and slowly increases to the rated operation of the specified conditions. The items to be checked during the test run are whether there is abnormal sound, change in the temperature of the self-aligning ball bearing, leakage or discoloration of the lubricant, and the like. If an abnormality is found, stop the operation immediately, check the machine, and remove the bearing check if necessary.

TIMKEN bearing temperature can generally be estimated based on the external temperature of the bearing housing. However, it is more accurate to directly measure the temperature of the outer ring of the bearing by using the oil hole. The bearing temperature gradually rises from the start of the operation, and the temperature is usually stable after 1 to 2 hours. If the bearing is poorly installed, the temperature will rise sharply and an abnormally high temperature will occur. The reasons are such as excessive lubricant, too small bearing clearance, poor installation, excessive friction of the sealing device, and the like. In the case of high-speed rotation, the selection of TIMKEN bearing structure and lubrication method is also the cause.

The rotation sound of TIMKEN bearings is checked with a stethoscope, etc., and there are strong metal noise, abnormal sounds, irregular sounds, etc. to explain abnormalities. The reasons are poor lubrication, poor accuracy of the shaft or housing, bearing damage, and foreign matter intrusion.

The surface of the steel under transient high temperature acts on the oxygen in the air and rises into a very thin (20-30 nm) thin layer of iron oxide. It is worth noting that the thickness of the oxide layer is corresponding to the test results of the total thickness of the surface-grinding metamorphic layer. This shows that the thickness of the oxide layer is directly related to the grinding process and is an important indicator of the quality of the grinding.

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Principles and functions of grease in NTN bearings

Our customers always have some improper use methods when using all kinds of NTN bearing grease. Today we will explain the principle and function of the grease in the bearing.

1, the principle of the use of grease

Everyone is a liquid solution that is a very thick solution. This grease is composed of a reticulated soap fiber whose structure determines that it can adsorb a large amount of lubricating oil and make it work properly. But as you can imagine, if a sponge is squeezed, the water will flow out. Grease is also squeezed out of the lubricating oil, but the grease in the NTN bearing is rarely directly squeezed and drained, because a freshly lubricated imported bearing is moving in the inner space of the bearing during running. Its main working principle is "temperature".

2, the practical function of grease

The main reason for draining grease to the sliding surface is the increase in temperature of the grease around the NTN bearing. When the bearing starts to run normally, the grease will reach the sliding friction surface. Lubrication begins to work as the temperature increases.

Advantages of NTN imported bearings with grease lubrication:

1) Individual bearing points must be refueled by hand. If the grease is used, it will save trouble and avoid accidents caused by lack of oil.

2) The grease itself has a sealing effect, which allows the use of a mechanism with a low degree of sealing to achieve a simplified design.

3) Experience has shown that lithium grease lubrication has a lower temperature rise and longer bearing life than a drop method in a certain speed range (n<20000r/min or dn<20000mm.r/min).

2, NTN imported bearing lubrication theory basis: the lubrication mechanism of the bearing is the theory of elastic fluid dynamic pressure lubrication.

3. NTN bearing failure type and lubrication relationship: Most of the failure causes are caused by faults in the assembly and poor sealing. A small number of failures are caused by wear, gluing, corrosion and overheating due to lack or excess of lubricant or quality failure.

4. Basic characteristics of grease and general criteria for selecting grease:

When selecting grease, you must choose the conditions of use (temperature, speed, load。

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