Roller Bearing Designation Method
When specifying roller bearings for industrial applications, there are various methods for identifying the bearings for use in a particular job. To best understand the details associated with roller bearing designations, it is important to understand that all roller bearing types, regardless of their individual characteristics, are usually designated according to an internationally accepted standard. This standard of designation identifies all of the characteristics of the bearing and provides a common language in which to communicate information when ordering and ordering bearings.
There are a number of key pieces of information typically found in roller bearing designations. In general, these pieces can include a bearing type code, a bore size designation, a number of rollers, a radial internal clearance code, contact angles, and other special options based on the design of the bearing. Additionally, many industrial bearings have specific designations associated with them in which the application, environmental conditions, and necessary options are specified. For example, a bearing designated as 6202-2rs may indicate a bearing with a 6202 bore size, 14mm outer diameter and 5mm inner diameter, with two-sided lip seals on both sides of the bearing, and a medium radial internal clearance.
Each of the components of a roller bearing designation provide information essential to proper operation of the bearing, and together they describe the pertinent characteristics necessary for an accurate order. Properly understanding a roller bearing designation can save time, improve the precision of order accuracy, and allow engineers to maximize performance when selecting bearings.
To begin understanding roller bearing designations, it is important to note that nearly all bearings found in today’s industrial applications come in two different categories: radial and angular contact. A radial bearing can be found in applications requiring relatively low friction, and is typically preferred when costs are to be kept low. In contrast, an angular contact bearing is often desired for applications requiring superior characteristics in terms of rigidity, bearing life, and maximum loads.
The most important information found in a bearing designation is the type code. This code is used to identify the type of bearing, such as radial, angular contact, and precision ball bearings, as well as other bearing assemblies. In general, a code of RB indicates a radial bearing, AC a roller bearing with contact angles, and B for a ball bearing. Several other codes exist for particular assemblies and options, such as SR for a special retainer, or J for a special set of shields.
After a type code, the bore size is usually listed. This is usually expressed in the form of two or three digits, such as a 7200 or 6203 series bearing. The diameter of the bore can be found in the first two digits (indicated in millimeters), while the last digit is an indicator of width (in tenths of a millimeter). When ordering bearings, this dimension is essential to ensure compatibility with the machine, shaft, or other component.
Next comes a number that indicates the number of rollers. This is expressed as a single digit, usually following the bore size designation. This number can range from one for a single row radial bearing, up to four for double or four row bearings.
The radial internal clearance code is near the end of a bearing designation and provides information about the amount of clearance present between the bearing’s rollers and the housing when mounted. Internal clearances can be expressed as a single letter from A to G, with A being the tightest and G being the loosest.
Contact angles are often indicated in bearing designations to indicate the contact angle between the bearing’s rollers and the race. This angle can often be adjusted within certain parameters to increase the bearing’s performance, so identifying the angle helps to optimize characteristics such as rigidity, speed and accuracy. Contact angles may be expressed as a single letter, with larger letters such as N, T, and W indicating a higher contact angle.
Finally, depending on the design, bearing special options may also be indicated in the designation. For example, a single letter such as X, Y, and J may indicate a special set of shields. Additionally, a single letter P can indicate a bearing with pre-loaded characteristics, making it appropriate for applications that require reduced noise levels or increased stiffness.
In summary, roller bearing designations provide engineers, technicians, and other customers with the information necessary to properly select, specify, and order bearings for a particular job. Knowing the type of bearing, its bore size, number of rollers, internal clearance, contact angle, and special options will help improve performance, reduce lead time, and maximize accuracy for demanding bearing applications.
