Bearing closures are available in two basic types - shields and seals. Both closure types are generally ordered as integral components of deep groove bearings.
Closures serve the same purposes with varying effectiveness - they exclude contamination, contain lubricants and protect the bearing from internal damage whilst being handled.
Closures are attached to the outer ring of the bearing. Seals are defined as closures which contact the inner ring, while shields clear the inner ring. Both are designed so that the stringent precision tolerances are not affected by their use.
Selection of Closures
Determining the proper closure for an application involves a trade-off, usually balancing sealing efficiency against speed capability and bearing torque. Shields do not raise bearing torque or limit speeds, but they do have low sealing efficiency. Seals are more efficient, but they may restrict operating speed and increase torque and temperature.
Another consideration in closure selection is air flow through the bearing. This is detrimental because it carries contamination into the bearing and dries out the lubricant. It is preferable to use seals if an air flow is present.
A number of types of closures are available from Barden. Please see the below table for operating information:
Deep Groove Bearing Closure Types
|Closures for deep groove bearings||Maximum speed|
|Type||Use||Material||Construction||Benefits||(dN units)||Operating Temperature Range||Limitations|
|SS Shields||Low torque, high speed closure that can provide lubricant retention & limited contamination protection||302 stainless steel||Precision stamping||Maximum lubricant space, resistance to vibration||Not limited by shield design||315°C 600°F||Limited contamination protection|
|AA Barshield||High speed rubber shield that provides improved protection from contamination without reducing allowable operating speeds||Rubber, metal insert||Rubber material bonded to metal stiffener||Good exclusion of contamination without a reduction in operating speed||Not limited by shield design||-38°C to 107°C -30°F to 225°F||May not prevent entrance of gases or fluids|
|FF Flexeals||Minimum torque, low friction seal that provides lubricant retention and contamination protection||Aluminium/ fiber laminate||Precision stamping and bonding||Excellent exclusion of contamination, resistance to aircraft hydraulic fluids||650,000||150°C/300°C Continuous 176°C/350°C Intermittent||May not prevent entrance of gases or fluids|
|UU Synchroseal||Specialised seal suitable for low torque applications||Teflon filled fiberglass||Thin ring, piloted in a specially designed inner ring notch||Low torque, positive seal that can prevent entrance of solid, gaseous or liquid contamination||100,000||315°C 600°F||Limited to low speed operation|
|YY Buna-N-Barseal||YY closures provide improved sealing performance compare to Flexeals||Buna-N rubber, metal insert||Rubber material bonded to metal stiffener||Excellent positive sealing to prevent the entrance of foreign contaminates||180,000||-54°C to 107°C -65°F to 225°F||Limited to relatively low speed and temperature operation|
|PP Polyacrylic Barseal||Polyacrylic Barseals provide a positive seal & allow for higher temperature operation than YY seals||Polyacrylic rubber, metal insert||Rubber material bonded to metal stiffener||Excellent positive sealing to prevent the entrance of foreign contaminates||180,000||-21°C to 130°C -5°F to 265°F||Requires relatively low speed operation|
|VV Viton Barseal||While similar in design to YY and PP seals, VV seals provide for high temperature operation||Viton rubber, metal insert||Rubber material bonded to metal stiffener||Excellent positive sealing to prevent the entrance of foreign contaminates||180,000||-40°C to 288°C -40°F to 550°F||Viton material provides excellent thermal & chemical properties and is the material of choice for aerospace bearings|