Stainless steel deep groove ball bearings are corrosion resistant when exposed to moisture and several other media.
They are available capped (with seals or shields) or open. Open bearings that are also available capped may have recesses in the ring side faces.
These bearings have a lower load carrying capacity than same-sized bearings made of high chromium steel.
Selection guidelines for different capping devices under various operating conditions are listed in table 1. However, these guidelines cannot substitute for testing a shield or seal in its application. For additional information, refer to Integral sealing.
The seals, which are fitted in a recess on the outer ring, make good, positive contact with the recess, without deforming the outer ring. The capping devices are available as:
are identified by the designation suffixes Z or ZS
are primarily intended for applications where the inner ring rotates
are fitted in the outer ring and form a narrow gap with the inner ring
are made of stainless steel
are supplied in different designs:
with designation suffix Z: either with (a) or without (b) an extension in the shield bore or the shield bore can extend into a recess in the inner ring (c)
fixed in the outer ring by a retaining ring and may extend into a recess (designation suffix ZS)
available on request: shields made of PTFE
are identified by the designation suffix RZ
provide better sealing effectiveness than shields
can be operated at the same speeds as shields
form an extremely narrow gap with the inner ring shoulder
are made of sheet steel reinforced NBR (oil and wear-resistant)
are identified by the designation suffixes RS1, RS1/VP311 or RS2
RS1 seals are made of sheet steel reinforced NBR and seal against the inner ring shoulder or against a recess in the inner ring side face.
Bearings with designation suffix VP311 are equipped with seals made of blue food-compatible NBR.
The material is FDA and EC approved. FDA approval is based on compliance with CFR 21 section 177.2600 'Rubber articles intended for repeated use' for use in contact with aqueous and fatty foods. EC approval is based on compliance with the overall migration requirements of the German BfR recommendation XXI for category 3 materials.
RS2 seals are similar to RS1 seals, but are made of sheet steel reinforced FKM.