What are the types of damage to spherical roller bearings
2020-11-11
Jinrui Bearing
Although the quality of spherical roller bearings is good and accurate, different types of damage may occur to the bearings due to different later use conditions. The following is the type of spherical roller bearing damage that Jinrui Bearing will bring you.
1. Scratches (two-body abrasive wear)
Hard particles moving with the shaft diameter are in contact with the friction surface. This is because the contact stress between the particles and the metal surface is low, and they make linear scars on the surface of the bearing bush; the hard particles half embedded in the surface of the bearing bush will also be on the surface of the shaft diameter. The linear scars are called scratches. The scratch is a two-body abrasive wear, and the direction of the linear scar is consistent with the direction of the shaft diameter.
If the lubricating oil film is ruptured, the hub peak on the surface of the shaft diameter will also scratch the bearing bush, and there will be many linear scars, which are also two-body abrasive wear. Hard particles embedded in the surface of the bearing shell and fall off, causing scratches and scratches.
The above-mentioned particles are mostly iron powder and sand. Scratches cause the surface of the friction pair to be roughened, thereby reducing the bearing capacity of the lubricating oil film, and forming new hard particles and hub peaks that can scratch the friction surface, causing a vicious circle.
2. (Three-body) abrasive wear
The smaller hard particles that enter the bearing gap move between the two friction surfaces and produce extremely high contact stress on the friction surfaces, forming three-body abrasive wear, which is similar to grinding, causing wear on the bearing bush and shaft diameter surface. The high contact stress between the hard particles and the friction surface causes plastic deformation or fatigue damage on the friction surface of the ductile metal, and embrittlement or peeling of the friction surface of the brittle metal.
The scars of abrasive wear are also linear, and the direction is also consistent with the direction of shaft diameter movement. When there is edge contact, lack of lubricating oil or oil film rupture, severe abrasive wear will occur. Abrasive wear will cause the shaft diameter and (or) the geometric size and shape of the bearing bush to change, loss of precision, and increase in bearing clearance, which will cause the performance of the sliding bearing to deteriorate sharply before the expected life.
3. Gluing (gluing)
When the lubricating oil film is broken or lacking in oil, a large friction factor causes a large amount of frictional heat to be generated and the bearing temperature rises. At high temperatures, the low melting point metal on one friction surface softens and adheres to the other friction surface. With the shearing effect formed by the rotation of the shaft diameter, the adhered metal is separated from the original surface and transferred to the other friction surface. Cause obvious pits and raised scars on the friction surface. This damage is adhesive wear.
When seizure occurs, the friction increases sharply and the bearing temperature further rises, forming a vicious circle. When the adhesion is serious and the power of the shaft diameter rotation can no longer cut the bonding point, the shaft diameter movement will be terminated, commonly known as "shaft holding", and the bearing will be completely damaged.
4. Fatigue wear
Fatigue wear is also called fatigue damage. Under the repeated action of cyclic load, in the direction perpendicular to the sliding direction, fatigue cracks appear on the friction surface. The cracks develop perpendicular to the bearing surface to the depths, to the joint surface of the lining and the backing, and then to extend parallel to the friction surface. The rear material was peeled off the friction surface, causing pit-like damage.
5. Stripping
When manufacturing the bearing bush, if the bonding force between the lining layer and the backing is insufficient or poor, the material of the partial lining layer will be peeled off from the bearing bush under the action of the load during the operation of the bearing. Peeling is somewhat similar to fatigue peeling, but the periphery of the fatigue peeling pits is irregular, and the peeling pits caused by poor bonding are relatively smooth.
6. Corrosion
Lubricating oil is constantly oxidized during use, and oxidation often produces weak organic acids. It is corrosive to bearing materials, especially lead in cast copper-lead alloys. Its characteristic is that the lead comes off in dots, making the surface rough.
Strong inorganic acids are more likely to corrode the surface of steel journals.
After the tin in the tin-based bearing alloy is oxidized, a black hard covering layer composed of SnO2 and SnO is formed on the surface of the bearing bush, and the hardness is in the range of 200-600HS. This coating is extremely harmful to the bearing. It is very hard and can scratch the journal surface and reduce the bearing clearance.
7. Erosion
(1) Cavitation
Cavitation is a form of surface damage that occurs when a solid surface is in contact with a liquid and moves relative to each other.
When the lubricating oil is in the low pressure area of the oil film, bubbles will be formed in the oil. After the bubbles move to the high pressure area, the bubbles will collapse under the action of pressure. The moment of collapse will produce great impact and high temperature. The solid surface is here. Under the repeated action of the impact force, the material will fall off due to fatigue, causing small pits on the friction surface, which then develops into sponge-like scars.
Cavitation often occurs in heavy-duty, high-speed sliding bearings with large changes in load and speed.
(2) Fluid erosion
Violent impact of fluid on the solid surface will cause fluid erosion, causing dot-like scars to appear on the solid surface, and the damaged surface will be smoother.
(3) Electric erosion
Electric sparks are generated between the friction surfaces due to electric leakage of motors or electrical appliances, causing spot scars on the friction surfaces. The characteristic is that the damage reciprocates on the harder journal surface.
8. Fretting wear
On the joint surface of the lining and the backing, the bearing bush and the bearing seat, due to the combined effect of micro-vibration (slip) and oxidation between the metal surfaces, three forms of adhesive wear, oxidation (corrosion) wear and abrasive wear are formed. Compound wear, called fretting, will cause point-like scars on the joint surface.
1. Scratches (two-body abrasive wear)
Hard particles moving with the shaft diameter are in contact with the friction surface. This is because the contact stress between the particles and the metal surface is low, and they make linear scars on the surface of the bearing bush; the hard particles half embedded in the surface of the bearing bush will also be on the surface of the shaft diameter. The linear scars are called scratches. The scratch is a two-body abrasive wear, and the direction of the linear scar is consistent with the direction of the shaft diameter.
If the lubricating oil film is ruptured, the hub peak on the surface of the shaft diameter will also scratch the bearing bush, and there will be many linear scars, which are also two-body abrasive wear. Hard particles embedded in the surface of the bearing shell and fall off, causing scratches and scratches.
The above-mentioned particles are mostly iron powder and sand. Scratches cause the surface of the friction pair to be roughened, thereby reducing the bearing capacity of the lubricating oil film, and forming new hard particles and hub peaks that can scratch the friction surface, causing a vicious circle.
2. (Three-body) abrasive wear
The smaller hard particles that enter the bearing gap move between the two friction surfaces and produce extremely high contact stress on the friction surfaces, forming three-body abrasive wear, which is similar to grinding, causing wear on the bearing bush and shaft diameter surface. The high contact stress between the hard particles and the friction surface causes plastic deformation or fatigue damage on the friction surface of the ductile metal, and embrittlement or peeling of the friction surface of the brittle metal.
The scars of abrasive wear are also linear, and the direction is also consistent with the direction of shaft diameter movement. When there is edge contact, lack of lubricating oil or oil film rupture, severe abrasive wear will occur. Abrasive wear will cause the shaft diameter and (or) the geometric size and shape of the bearing bush to change, loss of precision, and increase in bearing clearance, which will cause the performance of the sliding bearing to deteriorate sharply before the expected life.
3. Gluing (gluing)
When the lubricating oil film is broken or lacking in oil, a large friction factor causes a large amount of frictional heat to be generated and the bearing temperature rises. At high temperatures, the low melting point metal on one friction surface softens and adheres to the other friction surface. With the shearing effect formed by the rotation of the shaft diameter, the adhered metal is separated from the original surface and transferred to the other friction surface. Cause obvious pits and raised scars on the friction surface. This damage is adhesive wear.
When seizure occurs, the friction increases sharply and the bearing temperature further rises, forming a vicious circle. When the adhesion is serious and the power of the shaft diameter rotation can no longer cut the bonding point, the shaft diameter movement will be terminated, commonly known as "shaft holding", and the bearing will be completely damaged.
4. Fatigue wear
Fatigue wear is also called fatigue damage. Under the repeated action of cyclic load, in the direction perpendicular to the sliding direction, fatigue cracks appear on the friction surface. The cracks develop perpendicular to the bearing surface to the depths, to the joint surface of the lining and the backing, and then to extend parallel to the friction surface. The rear material was peeled off the friction surface, causing pit-like damage.
5. Stripping
When manufacturing the bearing bush, if the bonding force between the lining layer and the backing is insufficient or poor, the material of the partial lining layer will be peeled off from the bearing bush under the action of the load during the operation of the bearing. Peeling is somewhat similar to fatigue peeling, but the periphery of the fatigue peeling pits is irregular, and the peeling pits caused by poor bonding are relatively smooth.
6. Corrosion
Lubricating oil is constantly oxidized during use, and oxidation often produces weak organic acids. It is corrosive to bearing materials, especially lead in cast copper-lead alloys. Its characteristic is that the lead comes off in dots, making the surface rough.
Strong inorganic acids are more likely to corrode the surface of steel journals.
After the tin in the tin-based bearing alloy is oxidized, a black hard covering layer composed of SnO2 and SnO is formed on the surface of the bearing bush, and the hardness is in the range of 200-600HS. This coating is extremely harmful to the bearing. It is very hard and can scratch the journal surface and reduce the bearing clearance.
7. Erosion
(1) Cavitation
Cavitation is a form of surface damage that occurs when a solid surface is in contact with a liquid and moves relative to each other.
When the lubricating oil is in the low pressure area of the oil film, bubbles will be formed in the oil. After the bubbles move to the high pressure area, the bubbles will collapse under the action of pressure. The moment of collapse will produce great impact and high temperature. The solid surface is here. Under the repeated action of the impact force, the material will fall off due to fatigue, causing small pits on the friction surface, which then develops into sponge-like scars.
Cavitation often occurs in heavy-duty, high-speed sliding bearings with large changes in load and speed.
(2) Fluid erosion
Violent impact of fluid on the solid surface will cause fluid erosion, causing dot-like scars to appear on the solid surface, and the damaged surface will be smoother.
(3) Electric erosion
Electric sparks are generated between the friction surfaces due to electric leakage of motors or electrical appliances, causing spot scars on the friction surfaces. The characteristic is that the damage reciprocates on the harder journal surface.
8. Fretting wear
On the joint surface of the lining and the backing, the bearing bush and the bearing seat, due to the combined effect of micro-vibration (slip) and oxidation between the metal surfaces, three forms of adhesive wear, oxidation (corrosion) wear and abrasive wear are formed. Compound wear, called fretting, will cause point-like scars on the joint surface.
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