Radial Ball Bearing Nomenclature and Numbering System
There are many different numbering systems used in the bearing industry today. The boundary dimensions for certain series of bearings are defined in various standards, such as ABMA, JIS and ISO. In addition, most manufacturers have created their own numbering systems that are a combination of the actual part, or bearing, number and a series of codes that define additional specifications.
Interchanging bearing numbers between different numbering systems requires attention to detail and full knowledge of the codes that define the specifications. AST’s Engineers and Sales reps are experts with all numbering systems and can assist you with breaking down any bearing part number.
To assist you in understanding AST Bearings’ radial ball bearing nomenclature and numbering system, we offer the following examples and codes.
Numbering Example of AST Inch Series Miniature Ball Bearings:
Example of AST Standard Metric Series Ball Bearings:
Note: No symbol for material code = high carbon chromium steel SAE 52100
Material Codes for AST Ball Bearings:
Ball Bearing Type Codes:
Ball Bearings Closure (seals and shields) Codes:
Ball Bearings Retainer (cages & ball separator) Codes:
Radial (Internal) Clearance Codes for Ball Bearings:
For bearings with bore diameter greater than 10 mm, codes are: C2, C0, C3, C4, C5 per ABMA Std. 20
Standard Greases for Ball Bearings
Standard Oils for Ball Bearings
There are hundreds of lubricants, both oils and greases, used in rolling element bearings. Different lubricants are available that are designed to operate in various conditions, such as high or low temperatures, high speeds, vacuum, extreme loads, and high moisture or humidity to name a few. In addition certain greases should not be used in miniature or instrument bearings due to increased noise levels. There are lubricants that are approved for use in the food industry and others that are qualified to US military specifications for use in the defense industry. Consult with an AST Applications Engineer to ensure the proper lubricant is specified.
Typically, the last code in a bearing part number identifies the lubricant. Aside from the codes for the standard lubricants listed above, the following system is used to identify the lubricant.
Ball Bearings Greases
G343 where G indicates grease, and the next 3 numerical digits 340 identifies the particular grease, in this case 343 is equal to Mobil 28 grease.
Ball Bearings Oils
L105 where L indicates oil, and the next 3 numerical digits 105 identifies the particular oil, in this case 105 is equal to Castrol Brayco Micronic 814.
Other Codes for Ball Bearings:
There are additional codes that may appear in various positions within a bearing part number. These include codes that indicate types of functional testing performed, such as noise or torque, type of packaging, paired duplex arrangements, special dimensions, and bore or OD calibration.