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Drop several drops of oil on the filter paper and take a clean red filter paper. After the lubricating oil leaks, if there is black powder on the surface and there is a sense of astringency by hand, it indicates that there are many impurities in the lubricating oil. Good lubricating oil has no powder and feels dry, smooth and yellow.
Grease is very critical if the Three Inspection process of using SKF bearings. The use of metamorphosed grease will not only fail to play its due role, but also damage SKF bearings.
① Oil flow observation method
One of them holds the lubricating oil to be checked, and take two Three Inspection measuring cups. Put the other one on the table, lift the measuring cup filled with lubricating oil 30-40cm away from the table and tilt it, let the lubricating oil flow slowly into the empty cup, and observe its flow.
The lubricating oil with good quality should flow slender, uniform and continuous from time to time. If the oil flow is fast and slow, and sometimes large pieces flow down, it means that the Three Inspection lubricating oil has deteriorated.
② Hand twisting
A good lubricant feels lubricity, less wear debris and no friction. Three Inspection Twist the lubricant between thumb and index finger and grind it repeatedly. If you feel a great sense of friction such as sand particles between your fingers,
it indicates that there are many Three Inspection impurities in the lubricating oil and it cannot be used again. You should replace the lubricating oil with a new one.
③ Illumination method
Lift up the lubricating oil with a screwdriver on a sunny day. At an angle of 45 degrees to the horizontal. Observe the condition of oil drops according to the sunlight. Under the sunlight, it can be clearly seen that there is no wear debris in the lubricating oil. It can continue to function. If there are too many wear debris, replace the lubricating oil.
Lubrication has an important influence on the fatigue life, friction, wear, temperature rise and vibration of NSK Bearings, especially rolling bearings. Three Inspection Without normal lubrication,
the bearing cannot work. The causes of NSK bearing damage show that about 40% of bearing damage is related to poor lubrication. Therefore, good lubrication of NSK bearing is an effective measure to reduce bearing friction and wear.
In addition, the lubrication of NSK Bearings has many functions, such as heat dissipation, rust prevention, sealing, mitigation of impact and so on.
The role of NSK bearing lubrication can be briefly Three Inspection described as follows
a. An oil film is formed between the two rolling surfaces or sliding surfaces in contact with each other to separate the two surfaces and reduce the friction and wear of the contact surface.
b. When oil lubrication is used, especially when circulating oil lubrication, oil mist lubrication and oil injection lubrication are used, the lubricating oil can take away Three Inspection most of the friction heat inside the bearing and play an effective role in heat dissipation.
c. When grease lubrication is used, it can prevent external dust and other foreign matters from entering the bearing and play a sealing role.
d. Lubricants can prevent metal corrosion.
e. Prolong the fatigue life of NSK bearing.
1、 Requirements for installation surface and installation site
If there are iron filings, burrs, dust and other foreign matters in the bearing, the bearing will produce noise and vibration during operation, and even damage the raceway and rolling element. Three Inspection Therefore, before installing the bearing, you must ensure that the installation surface and installation environment are clean.
2、 The bearing must be cleaned before installation
The bearing surface is coated with antirust oil. You must carefully clean it with clean gasoline or kerosene, and then apply clean, high-quality or high-speed and high-temperature lubricating grease before installation and use.
Cleanliness has a great impact on NSK bearing life and vibration noise. However, we would like to remind you that there is no need to clean and refuel the fully enclosed bearing.
3、 Selection of lubricating grease
Lubrication has a very important impact on the operation and service life of NSK Bearings. Here we briefly introduce the general principles of selecting grease. Lubricating grease is made of base oil, thickener and additives. The performance of different kinds and different brands of lubricating grease of the same kind varies greatly,
and the allowable rotation limit is different. Be sure to pay attention to it when selecting. The performance of lubricating grease is mainly determined by the base oil. Generally, the base oil with low viscosity is suitable for low temperature and high speed, and the base oil with high viscosity is suitable for high temperature and high load.
The water resistance of thickener determines the water resistance of grease. In principle, greases of different brands cannot be mixed, and even greases with the same thickener will have bad effects on each other due to different additives.
4、 Addition of grease
When lubricating bearings, the more grease the better, which is a common misconception. Too much grease in NSK bearing and bearing chamber will cause excessive mixing of grease, resulting in extremely high temperature.
The amount of lubricant filled in the bearing should be 1 / 2 ~ 1 / 3 of the internal space of the bearing, and should be reduced to 1 / 3 at high speed.
5、 Installation and disassembly of bearing
During installation, do not directly hammer the end face and non stressed surface of NSK bearing. Use pressure block, sleeve or other installation tools to make the bearing bear uniform force. Do not drive the installation through the rolling element.
If the mounting surface is coated with lubricating oil, the installation will be more smooth. If the fit interference is large, the bearing shall be put into mineral oil and heated to 80 ~ 90 ℃ before installation as soon as possible.
The oil temperature shall be strictly controlled not to exceed 100 ℃ to prevent tempering effect, hardness reduction and size recovery. In case of difficulty in disassembly,
it is recommended that you use the disassembly tool to pull outward and carefully pour hot oil on the inner ring. The heat will expand the bearing inner ring and make it easier to fall off.
6、 Selection of bearing radial clearance
Not all NSK Bearings require small working clearance. You must choose the appropriate clearance according to the conditions. In national standard 4604-93, the radial clearance of rolling bearing is divided into five groups – group 2, group 0, group 3, group 4 and group 5.
The clearance value increases from small to large, of which group 0 is the standard clearance. The basic radial clearance group is suitable for general operating conditions, conventional temperature and common interference fit; Large radial clearance should be selected for bearings working under special conditions
such as high temperature, high speed, low noise and low friction; Small radial clearance should be selected for precision spindle and NSK bearing for machine tool spindle; For roller bearings, a small amount of working clearance can be maintained. In addition, there is no clearance for separate bearings;
After installation, the working clearance of the bearing after installation is smaller than the original clearance before installation, because the bearing has to bear certain load rotation, as well as the elastic deformation caused by bearing fit and load.