Drawing for illustration of 6008-ZZ C3- ISB
DRAWING FOR ILLUSTRATIVE PURPOSES ONLY.
Shielded bearings
Shielded bearings are identified by the designation suffix Z and ZZ. The shields are made of sheet steel and their bore creates a labyrinth with the external cylindrical surface of the inner ring. Shielded bearings are used primarily in applications where the inner ring rotates. If it is the outer ring that rotates, there is the risk that grease may leak from the bearing, especially at high speeds.
Bearings with low-friction shields
The deep groove radial ball bearings of ISB® with low friction shields are identified by the designation suffixes: RZ for ball bearings shielded just on one side, 2RZ for those with shields on both sides. The shields are made of Nitrile-Butadiene-Rubber (NBR) with sheet steel reinforcement. This rubber is resistant to oil and wear. The shields form a very small gap with the external cylindrical surface of the inner ring and do not touch each other. This is why ISB® ball bearings with low-friction shields have a better seal and can work at the same speeds as the Z type shielded ball bearings. The operating temperatures vary from -40°C to +100°C. They can even work at a maximum temperature of +120°C but for short periods only.
Bearings with contact shields
The ball bearings with contact shields are identified with designation suffix RS and 2RS. The outside diameter of the seals sits in a recess in the outer ring that holds it in position without deforming it, providing a good seal at the same time. Likewise for the ball bearings with low-friction shields, the RS and 2RS seals are made of Nitrile-Butadiene-Rubber (NBR) with sheet steel reinforcement. Sharing the same composition material, the operating temperatures will be the same, in other words from -40°C to +100°C with peaks up to +120°C for short periods only. Excessive speeds and temperatures or other harsh working conditions could cause grease to leak from the inner rings.
Sealed Bearings
Bearing shields and seals help keep lubricant in and dust, water and other contaminants out. This type of bearing is lubricated for life and requires no future maintenance. The type of lubricant grease varies based on the sizes. To guarantee the correct use of the bearings, they should not be heated to temperatures beyond 80 °C and should not be washed.
Stainless Steel
ISB® stainless steel deep groove radial ball bearings have the same operational characteristics as standard bearings but have a lower load carrying capacity. ISB® stainless steel deep groove radial ball bearings are identified with the designation prefix SS.
Open Bearing
One of the most commonly used bearings, the open types are manufactured without seals to allow for the free circulation of either oil or grease, used in gearboxes and other environments where no foreign matter would be present, and a lubricant supply is available.
