Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
2022年4月11日
Causes of universal joint bearing failure
2022年4月12日

Common faults and necessary remedial measures of Timken thrust ball bearing

  • The clearance of Timken bearing in the United States refers to the movement of the bearing when one side of its inner ring or outer ring is fixed when it is not installed in the shaft or bearing housing, and then the unfixed side moves radially or axially. According to the moving direction, it can be divided into radial clearance and axial clearance.
  • The clearance during operation (called working clearance) has an impact on the rolling fatigue life, temperature rise, noise, vibration and other properties of imported bearings. 
  • When measuring the clearance of the bearing, in order to obtain a stable measurement value, the specified measurement load is generally applied to the bearing. Therefore, the measured value is larger than the real clearance (called theoretical clearance), that is, it increases the elastic deformation caused by the measured load.
  • However, for the roller bearing of Timken bearing in the United States, the elastic deformation is small and can be ignored. The internal clearance of the bearing before installation is generally expressed by theoretical clearance.Common faults and necessary remedial measures of Timken thrust ball bearing
  • The lubrication of bearing is to use oil film to separate the relatively moving rolling surfaces from each other, so as not to fail due to excessive wear caused by rough point contact. If users attach great importance to imported bearing lubrication technology, it can ensure stable performance and rotation accuracy during the given service life.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Rotate the outer ring and carefully wash the junction of cage, rolling body and raceway. Any previously hidden part of oil residue needs to be thoroughly cleaned. Timken bearings should be attached after washing clean, Youlin dry cleaning, clean lined neutral meter support dry, or slowly in the far-infrared drying oven. Common faults and necessary remedial measures of Timken thrust ball bearing
  • Since even dry cleaning, Youlin drying or drying, the whole process should not put the bearing ring to any frame or rolling element. Bearing oil can be removed from the oil sealed package and immersed in acid free 3% kerosene or gasoline before delivery test in practice.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Inspection of dripping lubricating oil and immediate delivery of dry or dry bearings shall be required. At this time, there is no oil film to protect the outer surface of the bearing. The inspectors are not allowed to directly contact the skin in the whole process.Common faults and necessary remedial measures of Timken thrust ball bearing
  •  The operators should wear clean gloves and paint with rust, but they must avoid mixing the antirust agent with the appearance of American Timken bearing, otherwise the deviation of the measurement results will be.Common faults and necessary remedial measures of Timken thrust ball bearing
  • It shall be delivered immediately or treated with rusty stock. After the whole inspection process is completed, the imported bearings shall be inspected. Take too long to avoid corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.Common faults and necessary remedial measures of Timken thrust ball bearing
  • If the bearing is dry or dry, check the outer surface without bearing oil film protection according to the regulations, drip lubricating oil and deliver it immediately. At this time, the manpower directly contacting the skin is not allowed in the whole inspection process. Common faults and necessary remedial measures of Timken thrust ball bearing
  • The operator should wear clean gloves and draw rust by hand, but it must be avoided to mix the hands on the rolling surface of the bearing with rust inhibitor, otherwise it will lead to the deviation of the measurement results.
  • The inspection of Timken bearings in the United States is completed immediately after delivery or rust counting. During the whole inspection process, try not to last too long to cause corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.Common faults and necessary remedial measures of Timken thrust ball bearing
  • The lubrication of imported bearings is divided into grease lubrication and oil lubrication. The advantage of grease lubrication is that the lubrication facilities are simple, the grease is not easy to leak, and has the ability to prevent water, air and other impurities from entering the bearing. 
  • Therefore, grease lubrication is widely used in general. Lubricate with oil under heavy load, high speed, high temperature and other working conditions.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Lubricating grease is composed of base oil, thickener and filler. The viscosity of base oil plays an important role in the lubricating performance of grease. The composition of thickener has an important impact on the performance of grease, especially temperature characteristics, water resistance and oil precipitation. 
  • Filler is mainly used to enhance the anti gasification, anti rust, extreme pressure and other properties of grease.Common faults and necessary remedial measures of Timken thrust ball bearing

Common faults and necessary remedial measures of Timken thrust ball bearing

  • Timken bearing and shaft diameter or bearing seat hole interference is small, and the press in method is often used for assembly. The simple method is to use a copper rod and a hand hammer to knock the bearing race with interference fit symmetrically in a certain order to make the thrust ball bearing press in smoothly. In addition, soft metal casing can also be driven by hand hammer or press.Common faults and necessary remedial measures of Timken thrust ball bearing
  •  If the operation is improper, the seat ring will be deformed and cracked, or the hammer will hit the seat ring without interference fit, which will make the raceway and bearing body indentation or the bearing will be damaged indirectly.
  • During assembly, if the interference between the bearing and the shaft diameter is large, the hot assembly method is generally adopted. Put the bearing into the oil barrel containing engine oil, and heat the outside of the oil barrel with hot water or flame. Common faults and necessary remedial measures of Timken thrust ball bearing
  • The process requires that the heated oil temperature be controlled at 80 ℃ ~ 90 ℃, generally not more than 100 ℃, and mostly not more than 120 ℃. Timken bearing is quickly taken out after heating and sleeved on the journal. Common faults and necessary remedial measures of Timken thrust ball bearing
  • If the heating temperature is too high due to improper temperature control, the bearing will be tempered and the hardness will be reduced, and the thrust ball bearing is easy to wear, peel off and even crack during operation.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Damage state: when the bearing rotates under load again, the raceway surface or rolling surface of the inner ring and outer ring presents fish scale peeling phenomenon due to rolling fatigue.
  • Cause: excessive load. Poor installation (non-linear) moment load, foreign matter intrusion and water ingress. Poor lubrication, improper lubricant and improper clearance of thrust ball bearing. Poor accuracy of bearing housing, uneven rigidity of bearing housing, large deflection of shaft, development caused by rust, erosion point, scratch and indentation (surface deformation phenomenon).
  • Measures: check the load and re study the bearing used, improve the installation method, improve the sealing device and prevent rust during shutdown. Use lubricant with proper viscosity and improve lubrication method. Check the accuracy of the shaft and bearing housing. Check the play.
  • Damage state: it presents a dark surface with slight wear, on which there are several micro cracks with a depth of 5-10m from the surface to the inside, and micro peeling (micro peeling) occurs in a large range
  • Cause: improper lubricant. Foreign matter has entered the lubricant. Poor lubricant causes rough surface. The surface finish of paired rolling parts is not good.
  • Measures: select lubricant to improve the sealing device and improve the surface finish of paired rolling parts.
  • Card injury
  • Damage state: the so-called stuck injury is the surface damage caused by the collection of minor burns in the part of the sliding surface injury. Linear scars in the circumferential direction of slide surface and rolling surface. The cycloidal scar on the end face of the roller is close to the clamping wound on the shaft ring surface of the end face of the roller.
  • Cause: excessive load and preloading. Poor lubrication. Foreign body bite. Inclination of inner ring and outer ring and deflection of shaft. The accuracy of shaft and bearing housing is poor.
  • Action: check the size of the load. The preloading shall be appropriate. Improve lubricants and lubrication methods. Check the accuracy of shaft and bearing housing.Common faults and necessary remedial measures of Timken thrust ball bearing
Specified conditions for regular inspection of SKF imported bearings
  • Damage state: the so-called fracture refers to a small part of the fracture due to the impact or excessive load on the retaining edge of the raceway wheel or the local part of the roller angle.
  • Cause: hit during installation. Excessive load. Poor use such as falling.
  • Measures: improve the installation method (use hot installation and appropriate tool clamp). Correct load conditions. The bearing is installed in place so that the retaining edge is supported.
  • Crack, crack
  • Damage state: the so-called crack refers to the crack damage of the raceway wheel or rolling element. If it continues to be used, it will also include cracks with crack development.
  • Cause: excessive interference. Excessive load, impact load. Stripping has developed. Heating and micro vibration wear caused by the contact between the raceway wheel and the mounting member. Heating caused by creep. The cone angle of the cone shaft is poor. The cylindricity of the shaft is poor. The fillet radius of the shaft step is larger than the Timken bearing chamfer, resulting in interference with the bearing chamfer.
  • Measures: proper interference. Check the load conditions. Improve installation methods. The shape of the shaft should be appropriate.
  • indentation
  • Damage state: dents on the raceway surface or rotating surface when biting into small metal powder, foreign matters, etc. Due to the impact during installation, a concave surface (Brinell hardness indentation) is formed on the spacing of the rolling elements.
  • Cause: foreign matters such as metal powder bite in. Excessive impact load during assembly or transportation.
  • Measure: impact the shaft sleeve. Improve the sealing device. Filter the lubricating oil. Improve assembly and use methods.
  • Pear peel pitting
  • Damage state: weak gloss dark pear skin pitting on the raceway surface.
  • Cause: foreign matters bite in during lubrication. Condensation due to moisture in the air. Poor lubrication.
  • Measures: improve the sealing device. Fully filter the lubricating oil. Use a suitable lubricant.
  • abrasion
  • Damage state: the so-called wear is the wear of raceway surface or rolling surface, roller end face, shaft ring surface and concave surface of cage caused by friction.
  • Cause: development caused by foreign matter intrusion, rust and electric corrosion. Poor lubrication. Slippage caused by irregular movement of rolling elements.
  • Measures: improve the sealing device. Clean the bearing housing. Fully filter the lubricating oil. Check the lubricant and lubrication method. Prevent non-linearity.
  • Micro vibration wear
  • Damage state: wear caused by relatively repeated small sliding between the two contact surfaces occurs on the contact part between the raceway surface and the rolling element. Due to the occurrence of reddish brown and black wear powder, it is also called micro vibration wear corrosion.
  • Cause: poor lubrication. Small amplitude rocking motion. Insufficient interference.
  • Action: use proper lubricant. Preload. Check the interference. Apply lubricant to the mating surface
  • Pseudo Brinell indentation
  • Damage state: during micro vibration, the wear of the contact part between the rolling element and the raceway wheel develops due to vibration and shaking, resulting in impressions accumulated like Brinell indentation.
  • Cause: during transportation, the vibration and swing of the bearing when it stops running. Oscillating motion with small amplitude. Poor lubrication.
  • Measures: fix the shaft and bearing housing during transportation. The inner ring and outer ring shall be packed separately during transportation. Add preloading to reduce vibration. Use appropriate lubricant.
  • Damage state: the so-called creep refers to the relative sliding between the mating surfaces when there is a gap on the mating surface of Timken bearing. In terms of the mating surface with creep, the mating surface presents a bright or dark mirror surface, and sometimes the page is damaged and worn.
  • Cause: insufficient interference or clearance fit. The fixing sleeve is not tightened enough.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Measures: check the interference and implement anti rotation measures. Tighten the set sleeve properly. Study the accuracy of shaft and bearing housing. Axial preloading. The side of the raceway wheel is fastened. Bond the mating surface. Apply to the mating surface? Lubricant.Common faults and necessary remedial measures of Timken thrust ball bearing
  • burn
  • Damage state: the raceway wheel, rolling element and cage are heated sharply during rotation until they change color, soften, deposit and damage.
  • Cause: poor lubrication. Excessive load (excessive preloading). Excessive speed. The clearance is too small. Intrusion of water and foreign matters. The accuracy of shaft and bearing box is poor and the deflection of shaft is large.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Measures: study lubricants and lubrication methods. Correct the selection of bearings. Study fit, bearing clearance and preloading. Improve the sealing device. Check the accuracy of the shaft and bearing housing. Improve installation methods.
  • Electroerosion
  • Damage state: the so-called electric erosion refers to the phenomenon that when the current flows in the contact part between the bearing raceway wheel and the rolling body, sparks are sent out through the thin lubricating oil film, and local melting and concave convex appear on its surface.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Cause: ground potential difference between outer ring and inner ring.
  • Measures: when setting the circuit, the current should not flow through the bearing part. Insulate the bearings.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Rust and corrosion
  • Damage state: rust and corrosion of bearings include pit rust, overall rust and corrosion on the surface of raceway wheel and rolling element.
  • Cause: invasion of water and corrosive substances (paint, gas, etc.). Improper lubricant. Water droplets are attached due to the condensation of water vapor. Stop when it is hot and wet. Poor rust prevention during transportation. Improper storage status. Improper use.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Measures: improve the sealing device. Study lubrication methods. Rust prevention measures during shutdown. Improve storage methods. Pay attention when using.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Installation scar
  • Damage state: axial linear scars on the raceway surface and rolling surface during installation and disassembly
  • Cause: the inner ring and outer ring during installation and disassembly are inclined, and the impact load during disassembly.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Measures: use appropriate tools and press to prevent impact load. Centering between each other during installation.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Discoloration
  • Damage state: discoloration of raceway wheel, rolling element and cage due to temperature rise and lubricant reaction.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Cause: poor lubrication. Reaction with lubricant causes hot oil immersion. The temperature rises greatly.Common faults and necessary remedial measures of Timken thrust ball bearing
  • Measures: improve lubrication methods.
  • It can be seen from the above that the axial clearance of Timken bearings with adjustable or non adjustable clearance shall be adjusted during assembly (but some bearings with non adjustable clearance do not need to leave axial clearance) to compensate for the thermal elongation of the shaft when the temperature rises, so as to ensure the normal operation of the thrust ball bearing body. Common faults and necessary remedial measures of Timken thrust ball bearing
  • If the axial clearance is too small, it will make the bearing difficult to rotate, heat, and even make the bearing body stuck or damaged; If the axial clearance is too large, it will cause abnormal sound during operation, and even cause serious vibration or damage to the cage.Common faults and necessary remedial measures of Timken thrust ball bearing