Bearing assembly quality inspection in two ways:

Visual method: When the motor is mounted on the Stainless steel slewing bearing cap bearing chamber by hand after turning the end cap, if the bearings rotate freely, flexible, no vibration and shaking up and down phenomenon, considered qualified.
Feeler method: the motor cover with bearing assembly on the base station for the mouth, with a 0.03mm thick feeler bearing radial clearance of the week, if the maximum gap in the middle position just above the (motor horizontal installation ), was assembled correctly and reliably, otherwise, is a poor installation. Cover position should be adjusted, re-assembly, until qualified.
(2) poor lubrication: The reason is a serious lack of grease or oil dry aging. As the motor at high speed friction and heat, resulting in high bearing temperatures and oxidation discoloration, manifested as ball bearings, cage, inner ring and its journal, etc. become brown or blue.
Prevention Methods: According to the motor running time, ambient temperature, load conditions, such as grease or bad four factors that determine its complement oil and oil change time. Under normal circumstances, the motor should run 6000 ~ 10000h fill oil 1; run 10000 ~ 20000h should oil 1, 2 or 4-pole motor oil change over the bearing chamber volume of 1/2 to 2/3, and should be of high quality lithium grease (Code ZL-2).
3 installation did not pair: If the installation is not right, you not only have beads bearing slide marks, but the ball uneven wear marks, but also produce skewed, with a feeler bearing radial clearance on both sides will vary, and quite different. May be due to a direct hit with an iron hammer over bearing outer ring; belt pull (gear meshing) too tight; make the drive pulley and the driven pulley is not parallel to the centerline. When it is skewed more than 1/1000, it will cause the bearing operating temperature is too high, slide and ball severely worn, shaft bending and cover bolts clamping surface is not perpendicular to the axis of the bolt.
Proper installation: smooth end face, and almost equal to the thickness of the bearing steel inner sleeve, the pressure in the bearing journal clean the correct position. Press-fitting force should be uniform, not too much. Then check the motor shaft radial different speeds allow deflection values.