Common failures and solutions of slewing bearings

Slewing bearing as a common mechanical parts in the current industrial machinery, because it has good performance advantages to improve the efficiency of industrial production is widely used. So in the long-term use of the process will inevitably appear a lot of faults, the following is a summary of common failure phenomena, cause analysis and solutions:

Common failures and solutions of slewing bearings:

1. Rattling:

Mainly manifested in the rotation of the “thump” sound or continuous friction sound, metal impact sound. The reason for the noise may swim raceway surface wear, insufficient lubrication leading to dry friction, cage fracture, rolling body collision, excessive clearance leading to shock vibration. The solution needs to be disassembled and inspected first to ensure that the condition of the rolling body. Re-lubrication optimization to avoid dry friction. Adjust the clearance (0.05~0.15mm). If the cage is broken to replace the cage.

2. Rotating stall:

The main manifestation of the equipment rotary inflexible with obvious obstacles or motor overload alarm. Usually the reasons are mounting surface flatness > 0.2mm / m, raceway into the foreign body, rotating parts were extruded, negative clearance set wrong. The solution needs to repair the mounting surface first, and then clean and seal upgrades after recalibration of the negative clearance.

3. Grease leakage: 

Mainly manifested in the seal out of grease oozing. The causes of this problem are usually worn seals, grease oxidization at high temperatures after thinning, equipment tilt angle is too large. The solution is to modify the sealing system and replace the grease while optimizing the grease injection cycle.

4. Broken or loose bolts: 

The main reason is that the bolt preload is not uniform, the material grade is not enough, or the environment caused by corrosion resulting in thread failure. Solutions include upgrading the bolts to ensure the strength of the bolts, standardizing the fastening process, and insulating the bolts from corrosive media by anti-corrosion treatment.

5. Early fatigue failure of the raceway: 

The main manifestation of the use of the life of less than 30% will appear spalling and cracking. Possible causes of this phenomenon are insufficient depth of hardened layer or hardness gradient is not reasonable, the design value does not meet the impact load, installation process errors lead to partial load. The solution is to re-test the depth of the hardened layer of the material to be ≥ 2mm, monitor the load data, and centering adjustment to ensure that the amount of bias ≤ 0.05mm

6. Gear ring broken teeth or wear: 

Mainly manifested in the gear meshing area broken teeth, pitting on the tooth surface. Possible causes of this phenomenon are gear side clearance is too small or too large, drive motor and ring line angle error > 0.1 °. The solution is to carry out phosphating treatment on the tooth surface to repair the shape of the gear. Adjust the meshing side clearance in 0.1 ~ 0.3mm

In the use of slewing bearings should pay attention to preventive maintenance to avoid slewing bearing failure problems, mainly through regular testing of clearance changes (allowable wear ≤ 20% of the initial value) infrared thermal imaging camera to detect the operating temperature in the event of abnormal warming >> 15 ° C need to be shut down to check then. Lubrication management is also essential in the prevention, you can establish a lubrication ledger, record the grease injection volume and cycle, can also use automatic lubrication system to avoid dry friction on the slewing bearing damage. Coastal equipment should pay special attention to an annual anti-corrosion coating repair to ensure corrosion attack. In fact, the failure of slewing bearing mostly originates from improper design, installation or maintenance. The service life of the slewing bearing can be extended by fine care and upgrading of the material process.