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About Ball Bearings

Ball bearings used in dental highspeed handpieces reduce rotational friction to allow the spindle/chuck assembly in the turbine cartridge (and the bur, when inserted) to spin at speeds from 250,000 to 500,000 rpms. This makes the highspeed dental turbine one of the fastest rotating devices in the world.

The highspeed ball bearing is comprised of:

  1. Outer ring or outer race
  2. Inner ring or inner race
  3. Cage or retainer or separator
  4. Balls
  5. Shield

Common dental ball bearing designs

  1. Angular contact
  2. Radial or deep-groove
Bearing Breakdown

Angular contact

Outer ring has full shoulders and inner ring has a relieved and unrelieved shoulder. Features symmetrical cages that enhance performance and extend bearing life as each ball is fully supported and completely surrounded by the cage. Must be axially preloaded with springs or o-rings to ensure contact with the full unrelieved shoulder.

Angular Contact Bearing

Angular Contact vs Radial Ball Bearings

Angular Contact Radial
Angular Contact Bearing Sample Radial Bearing Sample
Quieter operation and longer life Widely available
Higher cost Lower cost
Should be handled by experienced technician Easy to handle and install
OEM preferred design Repair and third-tier manufacturer preferred

Balls

The balls roll between the inner and outer rings and can be made of steel or ceramic-hybrid.


Cage

Also called retainer or separator. Secures ball position between the 2 rings. It can be made of various materials (e.g. Torlon, Phenolic). When the cage breaks, the bearing fails.


Deep-groove

See radial


Inner ring or inner race

Inner portion of the ball bearing made of steel that press fitted onto the spindle/chuck and rotates along with the balls and the spindle/chuck assembly.


Outer ring or outer race

Outer portion of the ball bearing made of steel that remains stationary when the handpiece is in operation.


Radial or deep-groove

Has full shoulders on both inner and outer rings so they won’t disassemble during handling and handpiece installation.

Radial Bearing

Retainer

See cage


Separator

See cage


Shield

Helps prevent debris from entering the bearings and helps keep lubricant in.


Welded Slinger

Reduces suckback and minimizes debris entering bearing (need technical details about how many points of attachment and how better vs pressed slinger).

Welded Slinger Sample Bearing

XTRAlon

GRW premium cage material designed for the most demanding requirements in terms of friction, thermal stability and wear. The unique production method involving the chemical binding of solid lubricant to the base polymer polyamidimide (PAI) creates a homogeneous, dense fabric, which offers little opportunity for attack by the superheated steam during autoclaving. Click here for more information from GRW.


XTRALube

Lubricant developed by GRW that optimizes lubrication conditions for highspeed applications ensuring adequate lubrication for the lifetime of the bearing. Click here for more information from GRW.