Bearing maintenance, cleaning, overhaul, lubrication and installation

First, the cleaning of the bearing

When disassembling the lower bearing for inspection, first record the appearance of the bearing, confirm the residual amount of the lubricant, and then wash the bearing after sampling the lubricant for inspection. As a cleaning agent, gasoline and kerosene are commonly used.
The cleaning of the removed bearings is divided into coarse cleaning and fine cleaning. They are placed in the container respectively, and the metal mesh bottom is placed first so that the bearing does not directly contact the container. In rough 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.
Bearing inspection and judgment: In order to judge whether the removed bearing can be used, it should be checked after the bearing is cleaned. Check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase of the bearing clearance, and the damage and abnormality that are irrelevant in 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.

Second, the lubrication of the bearing

The purpose of bearing lubrication:

The purpose of lubrication of rolling bearings is to reduce internal friction and wear of the bearings, to prevent sticking, and the lubricating effect is as follows.
(1) Reduce friction and wear.
In the mutual contact portion of the ferrule, the rolling element and the retainer constituting the bearing, metal contact is prevented, and friction and wear are reduced.
(2) Extend the fatigue life.
The rolling fatigue life of the bearing is prolonged when the rolling contact surface is well lubricated during rotation. Conversely, if the oil viscosity is low and the thickness of the lubricating oil film is not good, it is shortened.
(3) Discharge friction heat and cool.
The circulation oil supply method or the like can be used to discharge heat generated by friction or heat from the outside to cool. Prevent the bearing from overheating and prevent the lubricant from aging itself.
(4) Others: There are also effects of preventing foreign matter from entering the inside of the bearing or preventing rust and corrosion.

Lubrication method:

The lubrication method of the bearing is divided into grease lubrication and oil lubrication. In order to make the bearing function well, first, choose a lubrication method that suits the conditions of use and the purpose of use. Lubricity of oil lubrication predominates if only lubrication is considered. However, grease lubrication has the advantage of simplifying the structure around the bearing and comparing the advantages and disadvantages of grease lubrication and oil lubrication.

Third, the installation of the bearing:
Whether the bearing is installed correctly affects accuracy, life and performance. Therefore, the design and assembly department should fully study the installation of the bearing. I hope to install according to the operating standards. The items of the job standard are usually as follows:
(1) cleaning the bearing and bearing related components;
(2) Check the size and finishing of the connected components;
(3) installation;
(4) Inspection after installing the bearing;
(5) Supply lubricant.

Generally grease is lubricated, not cleaned, and directly filled with grease. Lubricating oil is not necessary for cleaning. However, for instruments or high-speed bearings, it should be cleaned with clean oil to remove the rust inhibitor applied to the bearing. The bearing with the rust preventive removed is easy to rust, so it cannot be placed. Furthermore, bearings that have been sealed with grease are used without cleaning.

The mounting method of the bearing varies depending on the bearing structure, fit, and conditions. Generally, since the shaft is mostly rotated, the inner ring needs an interference fit. Cylindrical bore bearings, press with multiple presses, or use hot charging methods. 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. When dry ice is used as the coolant and the shrinkage is installed, the moisture in the air will condense on the surface of the bearing. Therefore, appropriate rust prevention measures are required.
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Analysis of different fault life of linear bearings

Fatigue life: The material of the main moving parts of the linear bearing reaches the limit, resulting in the accumulated time before the linear bearing fails.


Rated dynamic load: The load that a linear bearing can withstand when the service life is 10,000 rpm.


Equivalent dynamic load: The assumed load in which the actual load of the linear bearing is converted in accordance with the operating conditions for determining the dynamic load.


Wear life: The cumulative working time of the linear bearing before it reaches the specified limit due to normal wear. At today's linear bearing industry level, wear life > fatigue life should be used, but in fact traction motors are just the opposite.


Fault life: The cumulative working time before the linear bearing fails and the working capacity is lost.


Service life: It is the above three life-finding formulas. In theory, it refers to the fatigue life of linear bearings. In normal use conditions, it shows the wear life of linear bearings. When the conditions are abnormal and there are no defects in manufacturing, it represents the fault life. .
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