1. Regular inspection

In order to fully utilize and maintain the expected performance of bearings for a long time, it is necessary to effectively carry out regular maintenance (regular inspections). It is important to detect faults early and prevent accidents before they occur, in order to improve productivity and economy.

1.1 Cleaning

When disassembling the bearing for inspection, first use photography and other methods to make appearance records. In addition, it is necessary to confirm the amount of remaining lubricant and sample the bearing with the lubricant.

a. The cleaning of bearings can be divided into rough cleaning and fine cleaning, and a metal mesh frame can be placed at the bottom of the container used.

b. During rough cleaning, use a brush or other tool to remove lubricating grease or adhesive in the oil. If the bearing is rotated in oil at this time, be careful not to roll due to foreign objects or other damage

c. During fine cleaning, slowly rotate the bearing in oil and carefully perform it.

The commonly used cleaning agents are neutral non aqueous diesel or kerosene, and sometimes warm alkaline solution is also used as needed. No matter which cleaning agent is used to filter, keep it clean. After cleaning, immediately apply anti rust oil or grease to the bearings.

1.2 Inspection and judgment

1.2.1 Fault identification method for bearings

The maintenance and upkeep of bearings can identify or predict whether there are faults in the running bearings without disassembly inspection, which is very important for improving productivity and economy. The main method is as follows:

a. Recognition through sound

Recognition through sound requires extensive experience. Must undergo sufficient training to recognize bearing and non bearing sounds. We will assign a dedicated person to carry out this work. The sound of the bearing can be clearly heard by sticking a listening device or stick to the casing.

b. Identification by operating temperature

This method belongs to the comparative recognition method and is only applicable in situations where the operating state does not change significantly. For this reason, continuous temperature recording is necessary. If only the temperature increases, there will also be irregular changes.

c. Identification by the state of the lubricant

Sample and analyze lubricants to determine whether they are contaminated with foreign objects or metal powders. This method is particularly effective for bearings that cannot be observed closely.

1.2.2 Inspection of bearings

Conduct regular maintenance, operation inspection, and inspection of bearings that have been disassembled during the replacement of peripheral parts to determine whether they can be reused for better or worse. To carefully investigate and record the dismantled bearings and their appearance, in order to clarify and investigate the remaining amount of lubricant, clean the bearings at the sampling site.

Secondly, check the condition of the raceway surface, rolling surface and mating surface, as well as the wear status of the cage, for any damage or abnormalities. To determine whether the bearing can be reused, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, and other subsequent inspection results. If any damage or abnormal situation is found in the bearing, the damage section should identify the cause and develop countermeasures. In addition, if there are several defects on the inspection result surface, the bearing cannot be used anymore and needs to be replaced with a new one.

a. Any one of the inner and outer rings, rolling elements, or cages has cracks or fragments.

b. Any one of the inner and outer rings or rolling elements has detachment.

c. The raceway surface, edge guards, and rolling elements are significantly damaged.

d. The cage is severely worn or the rivets are loose.

e. Rust and scratches on the raceway surface and rolling body.

f. There are significant indentations and scratches on the rolling surface and rolling body.

g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.

h. Overheating can cause severe discoloration.

i. The sealing ring and dust cover of the grease sealed bearing are severely damaged.

2. Shutdown inspection

Regular inspection of bearing seals to maintain good condition of bearings is an important task. The advantageous inspection time is usually arranged through regular shutdown inspection plans and knowing the bearing model and availability of bearing spare parts, usually through inspection work.

It is important to keep the bearings and lubrication clean.

Before inspection, the surface of the machine needs to be cleaned first, and then the parts around the bearings need to be disassembled. Oil seals are very fragile parts, so it is necessary to carefully disassemble, shear, and then carefully inspect the oil seals and their surrounding parts. If any signs of defects have appeared, they must be replaced. Poor oil seals can damage and cause severe equipment shutdown.

2.2 Checking Lubricants

Apply a small amount of lubricant and rub between your fingers. If there are pollutants present, feel them or apply a thin layer of lubricant on the back of your hand

2.3 Lubricant replacement

After draining the old oil from the oil lubricated bearings, if possible, add fresh oil and let the machine rotate at low speed for a few minutes. Collect residual pollutants as much as possible, and then drain the oil. The oil is filtered before use.

When replacing grease in bearings lubricated with grease, the use of a grease remover should avoid any contact with cotton material at any part of the bearing, as these residual energy wedges between rolling parts and causes damage, especially in the application of small bearings.

2.4 Covering Exposed Bearings

When inspecting bearings, do not expose them to pollutants or moisture. If work is interrupted, oil paper plastic sheets or similar devices should be used.

If cleaning an unmasked bearing without disassembly and inspection is possible, it should be washed with a brush coated with petroleum solvent, and then wiped dry with a lint free cloth or blown dry with compressed air (be careful not to let the bearing components start rotating). Use a small mirror and a probe similar to that used by dentists to check the track surface, retainer, and beads of the bearings. If the bearing is not damaged, relubricate according to the lubrication instructions provided by the original factory.

Do not clean encrypted covers or dustproof bearings; Just wipe the external surface. If the bearing is damaged, it needs to be replaced immediately. Replacing bearings during the fixed maintenance period is much more economical than the sudden shutdown caused by damaged bearings.

3. Inspection and troubleshooting during operation

The inspection items during operation include the rolling sound, vibration, temperature, lubrication status, etc. of the bearings. The rolling sound and vibration of the bearings are described earlier, and lubrication is introduced as follows:

3.1 The role of bearing lubrication

Lubrication has a significant impact on the fatigue life, friction, wear, temperature rise, vibration, etc. of rolling bearings. Without normal lubrication, bearings cannot be damaged. The reason for bearing damage indicates that about 40% of bearing damage is related to poor lubrication. Therefore, good lubrication of bearings is an effective measure to reduce bearings. In addition, the lubrication of bearings also has various functions such as heat dissipation, rust prevention, sealing, and impact mitigation. The functions of bearing lubrication are as follows:

a. A layer of oil film is formed between the two rolling or sliding surfaces in contact to separate the two surfaces, reducing friction and wear on the contact surfaces

b. When using oil lubrication, especially when using circulating oil lubrication, oil mist lubrication, and oil spray lubrication, the lubricating oil can take away most of the internal heat of the bearing and effectively dissipate heat.

c. When using grease lubrication, it can prevent external dust and other foreign objects from entering the bearing, playing a sealing role.

d. Lubricants have the effect of preventing metal corrosion.

e. Extend the fatigue life of bearings.