How to repair KOYO bearings



1, KOYO imported bearings cleaning

When disassembling the imported bearing for inspection, first record the appearance of the bearing, confirm the residual amount of lubricant, and after sampling the lubricant for inspection, wash the bearing. As a cleaning agent, gasoline and kerosene are commonly used. The cleaning of the removed bearing is divided into coarse cleaning and fine fine washing. In the container, the metal mesh bottom is placed first, so that the bearing does not directly contact the container. In the case of fine cleaning, if the bearing is rotated with dirt, it will damage the rolling surface of the bearing and should be noted. In the rough cleaning oil, use a brush to remove the grease and the adhesive. After it is almost clean, it is transferred to the fine wash.

Fine washing is to carefully clean the bearing while rotating it in the cleaning oil. In addition, the cleaning oil should always be kept clean.

2, KOYO imported bearings for maintenance and judgment

In order to determine whether the removed 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 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 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, and ribs. The higher the importance of bearings, the more careful inspection is required.

The judgment of whether or not to reuse is determined in consideration of the degree of bearing damage, mechanical properties, importance, operating conditions, and the period until the next inspection. However, if you have the following defects, you can no longer use them. New bearings must be replaced.

There is a crack, or a gap, in any of the inner ring, the outer ring, the rolling element, and the cage.

There is a break in any of the ferrule and the rolling element.

There is significant slack in the raceway, ribs and rolling elements.

There are rust and damage on the raceway surface and the rolling elements.

There are severe indentations and marks on the raceway surface and rolling elements.

There is significant creep in the inner diameter surface of the inner ring or the outer diameter surface of the outer ring.

The discoloration caused by heat is obvious.

Bearings sealed with grease, seals, or dust caps are clearly damaged.
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Guarantee the operation accuracy and service life requirements of SKF imported bearings at high temperatures



Requirements for SKF Bearing Steels Working at High Temperatures Modern technologies such as nuclear power systems, jet engines, and gas turbines often operate at temperatures ranging from a few hundred degrees to thousands of degrees. Obviously, ordinary SKF imported bearing steels cannot be used. High temperature bearing steel or other high temperature resistant materials must be used. It is generally considered that the temperature condition exceeding 120 °C is regarded as the high temperature working condition. At this time, the normal bearing steel will undergo structural changes and the yield strength will decrease, and the accuracy will be gradually lost. When the working temperature of the SKF imported bearing exceeds the tempering temperature of the SKF imported bearing material, The hardness is significantly reduced, and the hardness drops sharply when the working temperature exceeds 180 ° C, and early fatigue and wear occur quickly. The central link to ensure the accuracy and service life of SKF bearings at high temperatures is to ensure that SKF bearings have sufficient hardness and dimensional and shape stability at high temperatures. Therefore, the following requirements are imposed on high temperature bearing steels:

1) The hardness at high temperature is not lower than HRC50~56; the metallographic structure is stable;

2) Good dimensional stability at high temperature, small temperature expansion coefficient, no significant structural change, good creep resistance and low residual stress;

3) Good oxidation resistance, the formed oxide film is firmly bonded to the substrate, and has good wear resistance and fatigue strength, good thermal shock resistance, can withstand rapid temperature changes, and has good thermal conductivity;

4) Other material properties that should be available as SKF imported bearing steel.
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