Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1103301
www . machinerylubrication.com | March - April 2019 | 39 ML ML us, the side closest to the motor or coupling is the drive or inboard side, while the other is the non-drive or outboard side. Decoding Bearing Numbers After the equipment tag has been located and the bearing numbers uncovered, you will see a series of numbers and letters. is code is the key to unlocking which type of bearing is in use within the machine. Depending on the manufacturer, the machine's age and the country in which it was made, the code may be displayed in different formats. Perhaps the most widely used system is employed by SKF bearings. It utilizes a numeric code for the bearing's basic desig- nation. is will contain many of the details you are most concerned about, including the roller type, size and configuration. A series of letters or numbers will also designate unique features, such as the use of shields or seals and if there are special clearances for this particular component. All of this information can be a goldmine when developing a reliability initia- tive, as each bearing will behave differently and may require different maintenance activities. An example of a bearing number in this format would be 6203ZZ. is designation indicates that the bearing is a single-row, deep- groove ball bearing that is for light duty with a 17-millimeter bore and shielded on both sides. e next designation is known as the Anti-Friction Bearing Manufacturers Associ- ation (AFBMA) code system. It has similar components in that it utilizes an alphanumeric system to indicate the bearing's dimensions and configurations. The code starts with the bearing's bore, which is followed by the type, width, outside diameter and any modifications, such as seals or shields. In this nomenclature, the bearing from the previous example would be denoted as 17BC02PP. Both of these systems, along with a host of others, can be cross- referenced against each other. Published tables are available to assist you in looking up the details for each system. Your spare-parts vendor can help you check this information as well. It generally will be most important to identify these numbers when you are performing calculations for greasing or vibration data. ey also can be useful when your equipment needs to be repaired and you want to replace a bearing with the same style or type. Guidelines for Rebuilds and Repairs Depending on the type of equipment, you may choose to perform rebuilds in-house. is can offer better control over which replacement parts are selected and installed prior to the machine being placed back into service, which is especially critical when replacing bearings. While the same size bearing normally is put back into service, the bearing's configuration may change. Using a bearing that is different from the type listed on the equipment tag can result in a main- tenance-induced failure. An example of this would be switching from a bearing that must be periodically regreased to one that is sealed and should not be greased. If this sealed bearing is installed and there is no indication of it now being a maintenance-free bearing, someone may apply grease to the housing and pressurize the cavity, forcing grease into places where it shouldn't be. Over time, the grease can build up and cause a failure or contribute to a failure mechanism due to increased heat or drag. erefore, whenever the replaced bearings are not the same as those that were installed initially, every effort should be made to document this in the computerized maintenance management system (CMMS) or on the equipment. When repairs are made by an outside company, such as a rebuild shop, documenta- tion should be provided detailing which bearing was replaced and what is now in the machine. Many shops can also make new equipment tags so the information on the tag can be kept up to date and accurate. Otherwise, an additional tag must be added to the machine stating it has 000 AAA OO AAAA 0 Bore Type Width & OD Cage Shields or Seals & Modifications Internal Fit Up Code Space No. Common Symbols Description Bore 1, 2, 3 17 or 105 Inside diameter of bearing in milli- meters; refer to bearing catalog Type 1, 2, 3 BC Ball bearing, single row, radial, non-filling slot BL Ball bearing, single row, radial, filling slot BD Ball bearing, double row, radial, non-filling slot BF Ball bearing, double row, radial, filling slot Width & OD 1, 2 00 6000 series bearing 02 6200 series bearing 03 6300 series bearing 04 6400 series bearing Cage Shields or Seals Modification 1, 2, 3 X Manufacturer a standard bearing cage P Metal shield permanently fastened S Contact seal permanently fastened G Snap ring groove on OD with snap ring Internal Fit Up 1 3 Internal clearance greater than standard AFBMA Code System for Bearings