Inspection of deterioration method of NSK bearing grease

    NSK bearings will encounter various problems during use. Today we will find out how to test the deterioration of NSK bearing grease.
    Grease is very critical in the use of NSK bearings. If a deteriorated grease is used, it will not only function as it should, but it will also damage the NSK bearing.
1 Oil flow observation method
Take two measuring cups, one of which is filled with the lubricating oil to be inspected, the other is placed on the table, and the measuring cup filled with lubricating oil is lifted off the table 30-40 cm and tilted to allow the lubricating oil to slowly flow to the empty cup. In the middle, observe the flow, the quality of the lubricating oil flow should be slender, even, continuous, if the oil flow suddenly and slowly, and sometimes there is a large flow, then the lubricant has deteriorated.
2 manual method
The lubricant is rubbed repeatedly between the thumb and the index finger. The better lubricant feels lubricated, less wear debris, and no friction. If you feel a large friction between the fingers, it means lubricating oil. There are many impurities inside, can not be reused, should be replaced with new lubricants.
3 lighting method
On a clear day, use a screwdriver to pry the lubricant at a 45-degree angle to the horizontal. Observe the sunlight and observe the oil droplets. Under the light, it can be clearly seen that there is no wear debris in the lubricating oil, which can continue to work. If the grinding debris is too much, the lubricating oil should be replaced.
4 oil drop trace method
Take a clean white filter paper, drop a few drops of oil on the filter paper. After the oil leaks, if there is black powder on the surface, touch the hand with a feeling of resistance, it means that there are many impurities in the lubricant, good lubricant No powder, it is dry and smooth by hand, and it has yellow marks.

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NTN bearing installation method

    Due to the structure, fit and conditions of the NTN bearing, in general, since the shaft is mostly rotated, the inner ring needs an interference fit. Cylindrical hole NTN bearings, press with a press, or use a hot charging method. For taper holes, mount directly on the taper shaft or with a sleeve.
 When installed in the outer casing, the general clearance fits a lot, and the outer ring has an interference amount, which is usually pressed by a press or a cold shrink fit method after cooling. With dry ice as the coolant and cold shrink fit, the moisture in the air will condense on the surface of the NTN bearing. Therefore, appropriate rust prevention measures are required.
1. Installation of cylindrical bore NTN bearing
(1) Method of pressing with a press
Small NTN bearings are widely used by presses. The pad is placed in the inner ring and pressed quietly to the inner ring with a press to closely contact the shaft shoulder. Installing the inner ring on the outer ring pad is the cause of the indentation and crushing on the raceway, so it is absolutely prohibited.
    When operating, it is best to apply oil to the mating surface beforehand. If you have to use a hammer to knock on the installation, you should put a block on the inner ring. This practice has often become the cause of NTN bearing operation, so it is limited to the case of small interference, can not be used for large interference, or medium and large NTN bearings.
For example, non-separable NTN bearings such as deep groove ball NTN bearings, where the inner ring and the outer ring need to be installed with interference, use the pad pad and press the inner ring and the outer ring simultaneously with a screw or oil pressure. The outer ring of the self-aligning ball NTN bearing is easy to tilt, and even if it is not an interference fit, it is better to install the pad.
For example, a split-type NTN bearing such as a cylindrical roller NTN bearing or a tapered roller NTN bearing can be mounted on the shaft and the outer ring respectively, and the inner ring and the outer ring respectively combined are combined. It is to steadily close the two so that the center of the two does not deviate, and the press-in will cause the raceway surface to be damaged.
(2) Method of hot charging
Large NTN bearings require a lot of force when pressed in, so it is difficult to press in. Therefore, the method of heating the NTN bearing in oil to expand it and then attaching it to the shaft is widely used. With this method, it is possible to complete the work in a short time without adding undue force to the NTN bearing.
     The heating temperature of the NTN bearing is based on the NTN bearing size and the required interference. The precautions for hot loading operations are as follows:
(a) Do not heat the NTN bearing to above 120 °C;
(b) In order to prevent the NTN bearing from directly contacting the bottom of the oil tank, it is best to consider placing the NTN bearing on the metal net or lifting the NTN bearing;
(c) Heating the NTN bearing to a temperature 20 ° C to 30 ° C higher than the required temperature so that the inner ring does not become cold during operation and is difficult to install;
(d) After installation, the NTN bearing is cooled down and the width direction is also contracted, so use a shaft nut or other suitable method to tighten it to prevent a gap between the inner ring and the NTN bearing shoulder.

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