Which ball bearing seals are available and why doesn’t igus need additional markings

Patrick Czaja | 13. November 2020

Many metallic rolling bearings are available as a sealed version. Ball bearing seals are usually mandatory for the metallic version, otherwise dirt will get into the running surfaces of the ball. They can combine with the lubricant and block the bearing run.


Metallic bearings must be protected

Metal ball bearings are also available as an open type. However, these are rarely used due to the problems mentioned above. Therefore, a dusty environment is sufficient to negatively influence the running properties over a longer period of time.


Ball bearings made of polymer or ceramic are usually only available as an open type

The reason is that these bearings do not need to be lubricated. The open construction has a great advantage with these materials. Any contamination that occurs can be easily removed,rinsed or blown out with compressed air. As a result, dirt and dust does not stick due to the lack of lubrication.


The sealing of metallic ball bearings is based on the principle of the shaft seal. The following manufacturer-specific seal designations are possible:

  • Z = one-sided sheet metal cover disc with gap seal
  • ZZ/2Z = as above, from both sides
  • RS = one-sided, grinding rubber seal
  • LB = as above
  • 2RS = as above, from both sides
  • LLU = as above, non-contact rubber seal, from both sides
  • EE = as above, touching from both sides, grinding
  • RZ = one-sided, non-contact rubber seal
  • LB = as above
  • 2RZ = as above, from both sides
  • LLB = as above

The seal designations are valid worldwide and, depending on the manufacturer, usually appear as a suffix after the respective DIN installation size.

Ball bearing seals & examples of igusĀ® ball bearings
Examples of ball bearing seals

igus xiros polymer ball bearing with cover plate

In the igus ball bearingsproduct range, customers also have the choice between different cover variants. Not all are available for every bearing installation size, but a one-sided cover plate is always available for selection.

igus ball bearing: cover variants (depending on installation size)
1. open type
2. cover plate on one side
3. labyrinth seal on both sides

Do you need assistance in selecting the right ball bearing for your application?


Our experts are always happy to advise and help you.

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