A shield (non-contact) or seal (contact) is often installed to retain lubricant and to prevent contamination from entering the bearing raceways. These are available in a variety of materials and configurations. Standard shield and seal configurations are called out in the individual bearing tables. Please contact a BYWB bearing engineer to discuss any special requirements.
BALL BEARING SHIELDS AND SEAL TYPES
Z TYPE SHIELD This is the most common type of shield. It is non-removable, being permanently staked to the bearing outer race with a small gap of approximately .005 inches between the inside diameter of the shield and the bearing inner ring. Since there is no contact with the inner ring, the torque and speed limitations are virtually unaffected and the performance of the bearing is almost identical to that of an open bearing. Standard material is 300 series stainless steel. Plastic fixed shields are also available on a limited basis. Most BYWBshielded bearings have metal Z type shields.
ZS TYPE SHIELD The ZS shield is identical to the fixed Z type shield, except that it is retained by an external snap wire that locates in a groove inside the rim of the bearing outer race. This is only an advantage if the user needs to remove the shield after manufacture of the bearing.
TS TYPE SEAL The TS type seal is made from glass-reinforced teflon. It is retained by an external snap wire to the bearing outer ring, but also lightly contacts the inner race land. This gives a high degree of protection from contamination, with a modest increase in torque.
D TYPE SEAL The D type seal consists of a molded Buna-N rubber lip seal with a steel insert. This provides maximum protection to the bearing against outside contamination. However, the high pressure of the lip seal itself results in greatly increased torque and friction losses that can cause heat build-up in higher speed applications. The seal material itself is rated to a maximum of 250 °F. This type of seal is only available for larger-sized bearings (R3 and above)