1. Accuracy composition
(I) Dimensional accuracy
·Related to the installation of bearings on shafts or bearing housings, covering the tolerances or allowable values of inner diameter, outer diameter, width, and chamfer dimensions.
·Specifically includes: allowable deviations of inner diameter, outer diameter, width, and assembly width.
·Allowable deviations of inner and outer diameters of roller sets.
·Allowable limit values of chamfer dimensions.
·Allowable width variation.
·Geometric accuracy involves the allowable values of inner diameter deviation, average inner diameter difference, outer diameter deviation, average outer diameter difference, and parallelism difference of the end face of the ring.
(II) Rotational accuracy
·Focus on the swing during the rotation process.
·Tolerance range of radial oscillation and axial oscillation of the inner and outer rings.
·Tolerance range of inner ring side swing.
·Tolerance range of outer diameter surface verticality.
·Inner ring allows lateral runout.
·Allowable variation in the inclination of the outer diameter surface.
·Allowable variation of thrust bearing raceway thickness.
·Allowable deviation and allowable variation of tapered holes.
2. Classification of precision grades
(I) Grading
·Gradually increasing from ordinary grade 0 to grade 6, grade 5, grade 4 and grade 2.
(II) Characteristics and applications of each grade
·Grade 0: Ordinary bearings, widely used in general bearing systems with rotation accuracy greater than 10um, such as ordinary machine tool speed change and feed mechanism, automobile and tractor speed change mechanism, general mechanical rotating mechanism such as ordinary motor, water pump, agricultural machinery.
·Grade 6 (6x): Advanced bearings.
·Grade 5: Precision bearings, used for precision bearing systems with rotation accuracy of 5 - 10um or higher speed, such as ordinary lathes (front support grade 5, rear support grade 6) and more precise instruments, meters and precision rotating mechanisms.
·4, 2nd grade: Ultra-precision bearings, used in ultra-precision instruments with rotation accuracy less than 5um or high speed, such as precision coordinate boring machines, precision grinder gear systems, precision instruments, meters and high-speed cameras.
III. Standards related
(I) International standard basis
· Countries use ISO standards as the basis, some of which are more stringent.
(II) Old codes and current standards
· Old code standards: G (level 0), E (level 6), D (level 5), C (level 4) and B (level 2).
· Current specifications: Mostly use German DIN standards, P0 (level 0), P6 (level 6), P5 (level 5), P4 (level 4), P2 (level 2).
·Model identification: In general, the name of P0 is omitted in the bearing model, and P6 and above are displayed in the model identification. For example, the actual accuracy level of 6205 is P0, but the mark is omitted, which is easy to be mistaken for P0 level non-precision level.
IV. Accuracy and price
· In addition to differences in processing technology, there are significant differences in the price of bearing accuracy levels. Among domestic bearings, the price of P6 precision bearings is 1.5 times that of P0, the price of P5 precision bearings is 2 times that of P0, and the accuracy of P4 is 2.5 times that of P5.
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About us
Since its establishment in 2003, SUN RISES GROUP LIMITED has been committed to providing customers with high-quality bearing products and solutions for many years. With rich industry experience and a professional technical team, we continue to innovate and strive to provide users with the best service and the most comprehensive product information. Our "Model Query" tool has become an industry benchmark, providing customers with convenient and efficient bearing selection support.
We always adhere to customer-centricity and create greater value for users through technological innovation and service improvement. For more information, please visit our website or contact our customer service team.
