High speed ball bearing for dental or medical handpieces

A medical, surgical, or dental handpiece bearing assembly comprising:

• an outer ring defining an outer raceway and an inner ring defining an inner raceway;
• said inner and outer rings defining a radial distance between said inner and outer rings;
• a first shield proximate a first axial end of said bearing assembly and extending from and integral with one of said inner and outer rings towards the other of said inner and outer rings;
• a second shield proximate a second axial end of said bearing assembly and extending from one of said inner and outer rings towards the other of said inner and outer rings;
• wherein said second shield is snap fit with one of said inner and outer rings to interlock said second shield and said ring together;
• said second shield being comprised of an engineering plastic of an amorphous polyetherimide to withstand temperatures of approximately 134° C.;
• wherein said first and second shields each have a length equal to at least about 50% of the radial distance between said inner and outer rings;
• a plurality of balls installed between said inner and outer rings and positioned to contact said inner and outer raceways;
• a retainer positioned between said inner and outer rings defining a plurality of pockets which receives said balls, said retainer comprising an engineering plastic having a base material selected from either a polyamide-imide (PAI) or a polyetheretherketone (PEEK) to withstand repeated sterilization, autoclaving, and application temperatures without degradation of mechanical properties;
• and
• a lubricating grease being disposed between the first shield and the second shield, adjacent to the plurality of balls, the lubricating grease comprising a mineral base oil with polyurea thickener.