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HOME > Technical Know-How > Bearing Dr > Handling of bearings
  As rolling beating is the part of precision machine a cautious handling is a must. Even a highly efficient equipment it would not function properly if it not handled as instructed. The followings shall be observed in handling the bearings.

(1) Bearing and the surroundings shall be maintained clean (no foreign material)
(2) Bearings shall be handled cautiously (no impact)
(3) Proper tools shall be used (no tools for other purpose)
(4) Bearings shall be protected from corrosion (wearing gloves when handling bearing and bearing shall kept away from corrosive gas)
 
 
  A life-span and performance of beating are affected by proper installation of bearing, and thus the following standards shall be considered in assembling process.

(1) Cleaning the bearing and accessories
(2) Checking the dimension and finish
(3) Assembly method
(4) Checking after assembling
(5) Lubricating

Considering the axial rotation of bearings, inner side shall be tightened, while outer side loosened when assembling.
 
 
  Operation test shall be conducted after assembling. Chart 2 summarizes the test process. When abnormal function is detected, the operation shall be stopped for inspection. Please refer to Chart 2 for cause and countermeasures.

Chart 1 Operation test process

Machines

Operation Method

Test Items

Small machine
Manual operation
If the test is acceptable, operation starts
● Blocked (foreign material, scratch, indentation)
● Irregular torque (poor assembly)
● Excessive torque (narrow gap / assembly error)
Power operation
Machine shall start at no-load and low-speed and gradually turn into to regular operation.
abnormal sound and bearing temperature
Leakage and discoloration of lubricant
Large machine
Power operation at low speed
Machine shall start at no-load and turn into low speed operation without power. If no problem is detected, it shall turn into power operation
Vibration and noise
Power operation
Same as power operation of small machine
Same as the items of small machine.

Chart 2 Abnormal operation and cause & countermeasures

Operation
Cause suspected
Countermeasures
Noise
Metallic high tone
Abnormal load
Fitting adjustment, bearing clearance check, preload adjustment, housing shoulder adjustment
Poor assembly
Axis/housing finish level, assembly improvement
Low /inappropriate lubricant
Refueling lubricant, selection of appropriate lubricant
Contact with rotating parts
Adjustment of contact part such as Labyrinth
Regular sound
Rust, scratch on surface
Bearing replacement, cleaning, sealing improvement and clean lubricant
Brinelling denting
Bearing replacement, cautious handling
Flaking on surface
Bearing replacement
Irregular sound
Excessive clearance
Fitting and bearing clearance check, adjustment of preload
Foreign material
Bearing replacement, cleaning, sealing improvement and clean lubricant
Scratch, flaking on ball
Bearing replacement
Temperature rising
Excessive lubricant
Reducing lubricant, selection of hardened grease
Low /inappropriate lubricant
Refueling lubricant, selection of appropriate lubricant
Abnormal load
Fitting adjustment, bearing clearance check, preload adjustment, housing shoulder adjustment
Poor assembly
Axis/housing finish level, assembly improvement
Excessive friction of creep sealing on fitting surface
Bearing replacement, fitting check, axis/housing adjustment, sealing improvement
Significant vibration
(shaking axis)
Brinelling indentation
Bearing replacement, cautious handling
Flaking
Bearing replacement

Poor assembly

Adjustment of perpendicularity of axis housing and side support

Foreign material

Bearing replacement, cleaning of parts, sealing improvement

Significant lubricant leaks & discoloration

Excessive lubricant, foreign material, friction powder
Optimization of lubricant level, bearing and lubricant replacement, housing cleaning
 
 
  (1) Refueling interval of grease
Grease tends to be performing poorly due to deterioration as times go by, requiring replacing the lubricant at appropriate interval, which depends on type, dimension and rotation speed of bearing. Fig 4.2 indicates the grease refueling interval depending on operation hours. That is, when bearing temperature exceeds 70℃, the interval of refueling shall be reduced half whenever the bearing temperature rises every 15℃.

(2) Replacement interval of lubricant
Replacement interval of lubricant varies depending on the condition and level lubricant. It needs to be replaced once a year when the operation temperature is below 50℃ at the environment with less foreign material, and the oil temperature is around 100℃, it needs to be replaced at every 3 months or earlier.