Common faults and prevention methods of rolling bearings

The normal operation of rolling bearings should be uniform, light, non blocking, and non loose when rotating by hand. The temperature during operation does not exceed 70 ℃, and when using a metal rod to listen, it emits a uniform sound of "rustling" without vibration.

The most common malfunction of rolling bearings is severe fever. If it is newly installed or cleaned or replaced with oil, it quickly heats up and causes severe fever upon operation, but there is no abnormal sound or vibration during operation. The reason is most likely that too much lubricating grease has been added, and only an appropriate amount of grease should be used. If the bearing is found to be "stuck" while experiencing a severe fever, the possible cause is that the bearing covers of the two shafts are pushing the outer ring of the bearing too tightly, not leaving enough axial clearance according to regulations, and the temperature rise during operation causes the shaft to elongate.

In some cases, the inner race of the bearing and the shaft fit too tightly, causing the inner race to expand, or the bearing seat and bearing outer race fit too tightly, causing the inner race to expand, or the bearing seat and bearing outer race fit too tightly, causing the outer race to deform under pressure. For the former, it is possible to first understand the assembly situation and whether the interference size left during shaft processing is too large. If this is the case, even though the bearings are hot installed, assembly will be more difficult. At this point, the bearing can only be removed, the journal polished to the appropriate assembly size, and assembled separately. The latter often occurs on split bearing seats, and if the screw of the bearing is loosened at this time, the bearing will become "flexible". You can add one or two layers of paper pads on the opposite side of the bearing to eliminate the problem. Because this type of bearing seat is first equipped with a 0.1mm~0.3mm thick paper pad at this location before processing its inner hole. Once the paper pad is removed, the hole is flattened.

In addition, if dust particles and impurities enter the raceway of the rolling bearing with the lubricating grease, there is also a possibility of jamming. Once this situation occurs, clean and change the oil. When repairing or replacing, even high-quality and clean lubricating grease should be carefully inspected before use. If a fever occurs after the rolling bearing has been running normally for a period of time, and there is dry friction noise or irregular impact sound when listening to it with a metal rod, it may be due to a lack of oil or the oil is no longer clean, or it may be due to damage to the rolling part of the bearing. All should be opened and cleaned, carefully inspected, and replaced with oil or bearings.

The rolling part of the bearing has a defect and must be replaced.

1. Rust

The bearings are stopped due to moisture or water in the oil, resulting in rust spots or rust on the surface or raceway of the rolling element.

2. Indentation

When hard material enters the raceway, pits are often pressed out on the surface of the raceway or rolling element. At this point, not only will there be noise or impact during operation, but excessive pits will also cause vibration and severe bearing fever.

3. Broken bearing ring

In addition to manufacturing reasons such as materials and heat treatment, if the interference size of the shaft is too large and the assembly method is improper, it can also expand and damage the inner and outer rings of the bearing. Improper design of the shoulder of the thrust bearing can also cause the dynamic ring to break under pressure. In addition to replacing the bearings, the cause should be identified. Exclude it.

4. Fatigue peeling on the surface of the raceway

This was originally normal wear and tear, but if used improperly, this wear and tear will accelerate rapidly.

5. Cage broken

Basically, it's a matter of material and manufacturing. Sometimes, if the cage is damaged during installation, it may also cause premature fracture, and a new bearing should be replaced.

6. Rolling element fracture

During operation, there will definitely be significant noise, even vibration, mostly due to improper material or heat treatment, and only replacement is necessary.

7. Current corrosion

During electric welding, if the current passes through the bearing, the contact between the rolling element and the raceway becomes hot, causing sparks, local burns, and leaving "scars". Therefore, during welding, it is necessary to make the "ground wire" of the welding as close as possible to the welding point, and in any case, welding current is not allowed to pass through the bearing.

8. Severe wear exceeding the limit

During operation, it is not only necessary to have a severe fever, but also to produce abnormal noises and vibrations. Due to the increased time gap, there will be "roaring" sounds, vibrations, and high temperatures during operation. When dust enters, the surface abrades and wears more quickly.

In addition, if the dimensions are not properly matched during processing, causing "inner circle" or "outer circle", it can also generate noise, high temperature, and even vibration.

The inner circle of the bearing is easier to detect because the inner ring of the bearing is "loose" on the shaft; When walking around the outer circle, it is necessary to carefully examine the outer ring or inner circle of the bearing to discover traces of their sliding against each other. When the inner circle is used to reduce the size of the journal by less than 1.5 mm compared to the size of the bearing hole, oxygen acetylene flame metal powder spraying welding or surfacing welding can be carried out, and then processing can be carried out. For bearings with a diameter less than 50 mm, the service conditions are good, and the bearings are only slightly loose on the shaft, but do not shake. Temporary emergency measures can also be taken, such as using sample punching to roughen the assembly surface, electric roughening, and surface tin plating. However, updates should be prepared in a timely manner. If the outer circle is used and the bearing seat is split, and the usage conditions are good, the paper pad added to the split surface of the bearing seat can be appropriately reduced or removed. If it is not feasible, a thin copper sheet of appropriate thickness can be added between the outer ring of the rolling bearing and the contact surface of the bearing seat, but at least a half circle or a whole circle should be padded, and small pieces should not be padded to avoid uneven pressure, deformation of the bearing outer ring, and more susceptibility to fever.

More about KYOCM Combined Bearing：

Composite bearing is a kind of roller bearing which can bear both radial load and axial load. The structure of the combined bearing is axial and radial bearing running at 900 °, the main load is borne by the radial bearing, and the axial bearing bears the lateral thrust.

Combination bearing is used together with profile guide rail or channel steel. There are two main types of profiles, I and C profiles. The combined bearing slides into the profile guide rail to generate the required linear movement. The combined bearing is welded with the flange plate for installation according to the application requirements. The assembly is mainly used for precise heavy vertical and horizontal movement.

https://www.kyocm.com/products/Combined-Bearing/743.html