More about SKF bearings Bearings basics Friction Protection Lubrication Robustness Precision / ABEC Mounting / Removing Cleaning		Precision/ABEC     Dimensions precision This is the main challenge for mass production. How can one ensure to make millions of bearings to exactly the same dimensions? It is very tough, if not impossible! Therefore, we have to accept that each bearing has dimensions with a small allowed deviation, called tolerance. Tolerances describe precision manufacturing capability; the smaller the tolerance, the more precise is the bearing. Tolerances have been classified to usual standards like ISO or ABEC. You must have heard about ISO! ISO means International Standards Organization and is used. You might have heard about ABEC? ABEC Means Annular Bearing Engineering Committee and is the standards organization for bearings in USA Both standards give fixed values for tolerances to bearings, depending on the size. Look at the table giving values for bearing 608 according to ABEC standards. Balls precision For regular and precise rotating, ball precision is important. It also decreases the friction in the bearing. For example, balls used in a 608 bearing do not differ more than ½ micron in diameter from one to another. Raceways precision and superfinishing Raceways must be precise to ensure precise ball guidance and good bearing behaviour. ISO or ABEC standards (see table before) state values for some parameters The raceway quality is also determined by the quality of the surface finishing, depending on many parameters related to SKF know-how. Want to know more? Cage precision Cage precision is really important as to avoid friction between balls and the cage body. Cage precision also allows a very precise ball dispatch between the rings to ensure regular load distribution in the bearing.
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