The impact sound of the rolling element and its control method. When large ball bearings or cylindrical rolling bearings are operated at low speeds, under pure radial loads, due to the tiny centrifugal forces of the rolling element, the rolling element in the non-load area will impact the cage. Or, the raceway can make noise. As the speed increases, however, this noise will diminish. To control the sound of rolling elements, reduce radial clearances and use NYZ that have cages made from flexible materials and reasonable structures.

1. Burning Damage

The bearing cannot rotate because it is sintered.

Analysis: The roller is damaged, the inner ring is expanding, the cage is disorganized, or the gap is getting smaller.

2. Over heating amage

Note: The outer and inner rings have black marks, which is the beginning of the burning process.

Heading: Change block type or style

Move the Heading block from position 7 up to position 6

Phenomenon: Bearing temperature is 1.5-2 times higher than normal or upper limit.

Analysis: The grease is dirty, too much or not enough or the bearing clearance is too low.

Note: There are three layers, one of the normal substrate and two of the overheated substrate.

3. Dump oil

Phenomenon: the bearing is overheated, and the grease leaks out of the oil seal.

Analysis: The grease is too thick or there is excessive gear oil in the bearing.

4. Loud noises and other abnormal sounds

Phenomenon – Vibration, acceleration or noise exceeding specified standards

The bearing clearance may be too large or the inner and outer rings are cracked or peeled.

5. Stripping

Phenomenon: The raceway and the rolling surface of the base body peel away, leaving a large and deeper area with mostly sharp edges.

Analysis: Material fatigue is caused by impact, eccentric loading, and improper heat treatment.

Note: Distribution according to the fault phenomenon. If the distribution is to one side, then it is due to axial force.

6. Cracks

Phenomenon – Cracks in inner and outer rollers

Analysis: Material fatigue is caused by impact, eccentric loading, and improper heat treatment.

Note: A symmetrical distribution around the circumference of a circle indicates that the rolling bearing is not round. If it is tilted it means shaft deflection or installation deflection.

7. Pitting corrosion

Phenomenon: Metal on the surface of the workpiece falls away from the base as dots with an easily recognizable area and depth. This phenomenon is also called pitting.

Analysis: Material fatigue is caused by impact, eccentric loading, and improper heat treatment.

Remarks: A symmetrical distribution around the circumference of a ring indicates that the bearing hole does not have a round shape; if the bearing is tilted it means shaft deflection or installation deflection.

8. Pinhole

Phenomenon: the pinhole falls and has a specific depth

Analysis: Material fatigue is caused by impact, eccentric loading, and improper heat treatment.

Note: Excessive load, lack of oil, etc., can lead to premature fatigue and mechanical damage during installation. Early fatigue and mechanical damage can occur during installation.

9. Rolling skin

Phenomenon: The metal from the surface of the workpiece falls off as a thin, rolled layer.

Analysis: Material fatigue is caused by impact, eccentric loading, and improper heat treatment.

10. Impact indentation

Phenomenon: Indentations from mechanical damage remain on the surface of the work, mainly in the form of bright depressions or reddish-brown spots that are excessively smooth.

Analysis of impact during handling, assembly, or excessive dynamic loads during operation

11. Electric corrosion

Phenomenon – Some patches and bands of corrosion

Analysis: Current flows through the bearing causing gap discharge, which leads to corrosion.

Note: The four layers of electro-corrosion metal are: the metamorphic layer (also called the changed layer), the overburned or normal layer, and the normal layer.

12. Discoloration

Phenomenon: The surface is discolored and oxidized. The color of the surface changes depending on how hot it is. It can be light blue, dark blue, brown or iron black.

Analysis: Thermal decomposition and adhesion of grease to the surface of the bearing are caused by abnormal temperature rises due to bearing failure or excessive temperatures during the heating of the ferrule.

The raceway noise of imported bearings, and the control method. The raceway noise is a continuous and slick sound produced by rolling elements on the raceway surface while the one-way bearing runs. All rolling bearings produce this basic, unique sound. . The sound of the raceway is heard in imported bearings, along with other sounds. Ball bearings have a raceway noise that is irregular and has a frequency of over 1000Hz. The main frequency of its sound does not vary with rotational speeds, but the total sound pressure increases as rotational speeds increase. The sound pressure of bearings that produce loud raceway sounds decreases with increasing viscosity. For bearings that produce small raceway sounds, sound pressure levels change from decreasing to increased when viscosity reaches about 20mm2/s. For increased. The sound pressure level generated by the raceway is reduced the more rigid the bearing seat. The raceway noise will be louder and more intense if the radial space is too small. To control raceway noise, you can select low-noise bearings imported from other countries, bearings that have very little waviness. You can also carefully choose the usage conditions. The noise produced by the track can affect the overall machine. Reduce the noise generated by the machine’s rolling track.

13. Wear and tear

Phenomenon: The working surface shows abnormal wear such as segmental wear or groove-like wear.

Analysis: Poor lubrication and sealing, mechanical contaminants entering, improper assembly, low bearing hardness, etc.

Note: divided into band wear and abrasive wear

 

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