Bearing issues
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There are two types of bearings: 6308RZ and 6308RZ Z1. Which one is better? Which one is best for use in motors?
This post was last edited by lihy on 2009-10-21 at 12:18; it was added that Z1 refers to the extreme value category of the bearing’s vibration acceleration, with the extreme values falling within the Z1 category as specified by the standards. Is RZ written incorrectly? It should be -2Z, which indicates that both sides have dust covers. For ordinary motors, when using them, it seems that there are no special requirements regarding the motor bearings; any bearings can be used.
For small motor bearings, the requirements are not very strict; of course, bearings with rubber oil seals can retain lubricant more effectively and extend their service life.
In most cases, for motors with a power rating of 40 KW or less, the requirements regarding bearings are not very strict. Of course, high-quality bearings will result in a longer service life, but at present, most companies are reluctant to invest in such high-quality bearings
First, it is necessary to clarify the difference between 6308RZ and 6308RZ Z1. Essentially, the structure of these two types of bearings is the same. The “RZ” designation indicates a non-contact seal bearing with a sealing ring on one side, while “Z1” denotes a low-noise bearing designed specifically for motors. Roller bearings generally have very low noise and vibration levels, but for motors, especially those with specific requirements regarding noise, it is recommended to use low-noise bearings. According to China’s JB/T7047-1999 standard, deep groove ball bearings are classified into four vibration level groups – Z1, Z2, Z3, and Z4 – based on their vibration value in dB. For measuring the vibration level of individual bearings, two units of measurement are currently used. One type is of the acceleration type, with its unit of measurement being decibels (dB); the group codes are Z1, Z2, Z3 ； The other type is the velocity type, whose unit of measurement is micrometers per second (um/s), with group codes ZV1, ZV2, and ZV3. These supplementary codes for the bearing vibration category are placed to the right of the bearing’s basic code. As for the advantage of bearings such as the 6308RZ and 6308RZ Z1 that you mentioned, as long as they are products from reputable manufacturers, there will be no problems; of course, using the 6308RZ Z1 in the motor would be better. But it is essential to prevent counterfeit and low-quality products.