In principle, all NTN bearings should be kept in their original packaging before installation. They need to be left in a clean, moisture-free, relatively constant temperature environment. Rolling bearings should be kept away from dust, water and corrosive chemicals. Shaking and vibration may permanently degrade the mechanical properties of the NTN bearing, so vibration must be avoided during handling and storage.
Basically, all NTN bearings must be stored horizontally, as some heavier bearings may be deformed by their own weight after standing for a long time.
Pre-coated greased (or sealed) NTN bearings require special care because the density of the grease changes after prolonged storage. Thus, when the NTN bearing is used for the first time, there will be a certain degree of rotational noise. Therefore, the shelf life of such NTN bearings should be controlled on a first-in, first-out basis.
clean
Cleaning is very important for rolling NN bearings. The surface roughness of the rotating surface of the NTN bearing ring and the rolling elements is usually 1/10 μm. Such a smooth surface is very sensitive to damage caused by contaminants. The lubricating layer between the rotating faces is usually 0.2 to 1 μm. Particle-shaped impurities larger than the particle size of the lubricant may be excessively crushed by the rolling elements to cause partial pressure in the NTN bearing steel, which may eventually cause permanent material fatigue. In addition to this, dust particles in the external environment can be up to 10 μm in size, which can also cause damage to NTN bearings. Therefore, a clean, dust-free environment is critical to the storage and installation of the bearings.
NTN bearings should be carefully installed and removed using suitable tools. Industry experts estimate that 16% of premature bearing failures are due to incorrect installation. For large installations (for example in production plants), conditional installations are usually strictly controlled and suitable NTN bearing mounting equipment can be used.
However, in maintenance or replacement work, the environment is diverse. Therefore, in order to ensure the longest service life of the NTN bearing, comprehensive preparation is necessary for bearing installation.
First of all, relevant documents, such as drawings, maintenance manuals, product manuals, etc., need to be carefully studied. Next, all NTN bearing components, such as shafts, spacers, covers, gaskets, etc., must be kept absolutely clean and free from contamination. The status of adjacent components should also be checked carefully.
In order to determine whether the removed NTN bearing can be reused, check the bearing after it has been cleaned. Carefully check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase in the NTN bearing clearance, and the presence or absence of damage to the dimensional accuracy. For non-separable miniature ball bearings, use one hand to support the inner ring horizontally and rotate the outer ring to check if it is smooth.
Separate NTN bearings such as tapered roller bearings can be inspected separately for the rolling surfaces of the rolling elements and the outer ring.
Large bearings cannot be rotated by hand. Pay attention to the appearance of rolling elements, raceways, cages, ribs, etc. The higher the importance of NTN bearings, the more careful inspection is required.
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