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AS AN ESSENTIAL, LIFE-SUSTAINING BUSINESS, AST BEARINGS WILL REMAIN OPEN AMIDST THE CORONAVIRUS PANDEMIC.

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Ceramic Ball Bearings

What is a Ceramic Ball Bearing?

Types of Ceramic Ball Bearings

Hybrid Bearings are made up of two materials. The balls are made from a ceramic material, usually silicon nitride Si3N4, while the inner & outer rings are made from traditional, heat-treated chrome or stainless steel. Full Ceramic Bearings on the other hand have both the inner & outer rings as well the balls manufactured from ceramic material, usually zirconium dioxide ZrO2, also known as zirconia. Nowadays, both hybrid and full ceramic bearings are considered quite affordable and are often the most economical solution when the end-user considers the cost of a failure and the total cost of ownership.

What Are Hybrid Bearings?

The most common configuration for a Hybrid Bearing is Silicon Nitride Si3N4 balls with either chrome or stainless steel rings. Compared to traditional steel balls, Si3N4 balls have the following desirable characteristics:

  • approximately 60% more lightweight than bearing steel
  • higher hardness: over 75 HRc
  • stiffer: higher elastic modulus
  • lower coefficient of thermal expansion
  • higher maximum operating temperature: 1000+°C
  • lower friction: highly polished surface finish

Another popular hybrid configuration is with zirconia ZrO2 balls instead of silicon nitride. The mechanical and thermal properties of ZrO2 are closer to that of alloy steel, which can be desirable in maintaining the bearing preload and contact angle over a broad range of operating temperatures. Consult an AST Applications Engineer for a full analysis of the operating conditions and potential failure modes.

What Are The Benefits of Hybrid Ceramic Bearings?

  • higher stiffness and rigidity reduces deflection
  • increased limiting speed (rpm)
  • less adhesive wear, no cold-welding
  • better lubricant life
  • lower noise levels & vibration
  • no electrical arcing through the balls

What Are The Applications For Hybrid Ceramic Bearings?

  • machine tool spindle
  • pumps - submersible, fuel, vacuum
  • dental drills
  • optical scanner
  • electric motors
  • aerospace applications
  • laboratory equipment
  • applications that requre higher speeds, longer life, and lower friction

What are Full Ceramic Bearings?

Full Ceramic Bearings are often the answer for extreme environments, such as high temperatures, corrosive chemicals, steam, and hard vacuum. These bearings have both the inner and outer rings in addition to the rolling elements manufactured from ceramic material. Like the balls in hybrid bearings, the rings in full ceramic bearings are typically manufactured from silicon nitride, Si3N4, or zirconia, ZrO2. Retainers in full ceramic bearings are typically made from high-performance plastics such as PEEK or PTFE. Full complement versions are also available.

CharacteristicsUnitChrome SteelStainless SteelNitrogen Enhanced Stainless SteelSi3N4ZrO2
Densityg/cm37,857,857,853,26,0
HardnessRc>60>58>60>75>75
E-Modulus210200218320200
Poissons Coefficient0,280,280,30,260,3
Expansion Coefficientx 10-6°C10,910,110,12,910
Top Temperature Limit°C1702605001000600
Corrosion Resistancelimitedgoodvery goodvery goodgood
Electrical Conductivityconductorconductorconductorisolatorisolator
Magnetismmagneticmagneticmagneticnot magneticnot magnetic

Benefits of Full Ceramic Bearings:

  • resistant to acid, salt and water, and blood
  • non-magnetic
  • lower coefficient of friction
  • resistant to electricity
  • corrosion-resistant
  • lighter, smoother and stiffer

Applications for Full Ceramic Bearings:

  • MRI equipment
  • vacuum environments
  • semiconductor manufacturing
  • radiotherapy
  • food processing industrie
  • any extreme environment requiring non-corrosive, non-conductive or non-magnetic bearings

An AST Applications Engineer should be consulted for a full analysis of the operating conditions and potential failure modes.

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