Engineering Reference

Miniature & Instrument Ball Bearings

Shields and Seals

Shields and seals are protective closures that retain lubricants and assist in preventing contaminants from reaching internal surfaces. When specifying a seal or shield, consideration should be given to the compatibility of the cage and enclosure type to allow for appropriate clearance. In torque-sensitive applications, it may be advantageous to use shields rather than seals because there are no contacting surfaces to create drag. The following includes the common types of shields and seals offered by NHBB. Please consult the factory for help in determining the appropriate seal or shield for your particular application.

Table of Shield and Seal Types

TypeDescriptionMaterialOperating Temp Max.*
Removable with snap wire
Minimal clearance
Most popular
Stainless steel 300 series600 °F
LSeal with snap wire
Provides minimal clearance to light contact resulting in low torque
Glass-reinforced PTFE400 °F
LBPL seal with backing plate
Excellent sealing characteristics
Glass-reinforced PTFE seal, metallic backing plate400 °F
Excellent sealing characteristics
Buna-N bonded to steel insert 250 °F
Excellent sealing characteristics
High cost
Viton® bonded to steel insert 400 °F
QSeal, lip riding
Excellent sealing characteristics
Glass-reinforced PTFE 400 °F
Q4Seal with protective shield, lip riding
Excellent sealing characteristics 
Glass-reinforced PTFE400 °F

*Rings and balls are heat stabilized to 300 °F.
Viton® is a registered trademark of DuPont.

 Type Diagrams

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D / D1

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