Bearing material:
Most ball bearings are made with the material of is GCr15 basic electric high carton chromium bearing steel( equivalent of JIS G 4805 SUJ2 steel), stainless steel 9Cr18(AISI440). As well as ceramic Si3N4. The cages are usually punch-pressed from brass strips H62 or steel 08,SPCC,or stainless 3Cr13,1Cr18Ni9,and fiber reinforced phenolic resin ,plastics,copper stock, Sheals are made with the material of steel 10 or 08AI,SPCC,stainless steel 1Cr18Ni9 The seals are made with the material of synthetic rubber and Teflon.
Rings material available: Chrome steel stainless steel, ceramic Si3N4, Ceramic ZrO2,Ceramic SIC.
For miniature ball bearings,There are main two choices for material used in ball bearings—Chrome steel or stainless steel. Since the material plays a major
Part in the peformance of a bearing in any given application. It is very important that the correct material is used. Note that the specified material applies to the load bearing components only.
The rings and the balls,The retainer and the shield(If used) are usually made from a different material and are subject to separate specification.
CHROME STEEL (AISI 52100 OR EQUIVALENT)
This is the standard material used for ball bearing applications where load capacity is the main consideration. The machinability of this steel is excellent, giving smooth, low noise raceway finishes, together with superior life. Chrome steel material is recommended in applications where corrosion is not a factor.
STAINLESS STEEL (AISI440 OR EQUIVALENT)
9Cr18 (equivalent of AISI440) martensitic stainless steel is the standard material for miniature and instrument ball bearings where corrosion resistance is more important than load capacity. The bearing part numbering system gives the appropriate codes for Stainless Steel, (prefix "S")
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The chemical composition of the material(GCr15)
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HARDNESS OF MATERIAL |
The hardness of bearing rings are HRC61-65,The ball are HRC62-66. | ||||||||||||||||||||||||
Zirconia (suffix "ZrO2")
• Good corrosion resistance to cold water and many chemicals
• Good high temperature performance up to 400C without cage
• Non magnetic and electrically insualting
• Lower speed and load than steel bearings
• Not suitable for low noise applications
• Higher fracture toughness than other ceramics so better for small shock loads
• Expansion similar to steel so not a problem to use with steel shaft at high temperature.
Silicon Nitride (suffix "Si3N4")
• Very good corrosion resistance to water, salt water and most chemicals.
• Good high temperature performance up to 1000C without cage
• Non magnetic and electrically insulating
• Lower speed and load than steel bearings but Si3N4 balls are used in high speed hybrid bearings.
• Not suitable for low noise applications
• Much lighter than steel or Zirconia
• Very low expansion at high temperature.
Silicon Carbide (suffix "SiC")
• Best corrosion resistance of the ceramics.
• Best high temperature performance up to 1600C without cage
• Non magnetic
• Electrically conductive
• Much lighter than steel or Zirconia
• Very low expansion at high temperature.
Balls: Chrome steel ,stainless steel, ceramic Si3N4, Ceramic ZrO2,Ceramic SiC.
For miniature bearings,PMB Main balls material is chrome( GCR15),Stainles Steel (9Cr18) and Ceramic Si3N4.
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Fundamental property data of ceramic and steel materials | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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