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Q12. What are "Super Precision", "Super High Precision", versus "Ultra Precision" bearings?

Some factories promote bearings as “Super Precision (MM),” “Super High Precision (MMV),” and “Ultra Precision (MMX)” bearings. These are all just factory defined terms to used describe ABEC-7 through ABEC-9 (ISO-P4 through ISO-P2) tolerances with one of them being a compromise between the two specifications.

More specifically, bearings called Super Precision (MM) are typically manufactured to ABEC-7 (ISO-P4) tolerances. Ultra Precision (MMX) bearings are usually manufactured to ABEC-9 (ISO P-2) tolerances. However, so-called Super High Precision (MMV) bearings are manufactured partly to ABEC-7 tolerances, but also partly to tolerances defined by ABEC-9 specifications. Super High Precision bearings operate with performance levels and running accuracy meeting ABEC-9 specifications; however, their remaining features meet ABEC-7 specifications and consequently are less expensive compared to fully ABEC-9 compliant (Ultra Precision) bearings. 

For more about official bearing tolerances and their definition by the ABMA and ANSI, please see our white paper entitled, "Bearing Tolerances and Precision Levels."


Did we miss something?  If you have another question for us, just let us know and we will do our best to provide you a prompt and accurate answer.  AST Bearings provides "value beyond the part."


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