Bearing tolerances include dimensional tolerance and rotary tolerance or dimensional accuracy and running accuracy, are regulated by ISO or JIS standards (rolling bearing tolerances) etc. For dimensional accuracy, these standards prescribe the tolerances necessary when installing bearings on shafts or in housings. Running accuracy is defined as the allowable limits for bearing run-out during operation.
According to dimension tolerances and runout accuracy, HCH deep groove ball bearings are ranged from ABEC-1 to ABEC-7. ABEC-1 is standard grade, while ABEC-3 is higher, ABEC-5 is much higher and ABEC-7 is the highest.
● Comparison of tolerance classifications of national standards
| Standard | Applicable standard | Tolerance class | ||||
| ANSI | ANSI/ABMA Std.20 | ABEC-1 | ABEC-3 | ABEC-5 | ABEC-7 | ABEC-9 |
| JIS | JIS B 1514 | Class0,6X | Class 6 | Class 5 | Class 4 | Class 2 |
| ISO | ISO 492 | Class0,6X | Class 6 | Class 5 | Class 4 | Class 2 |
| DIN | DIN 620 | P0 | P6 | P5 | P4 | P2 |
Symbols: The following symbols are used to identify boundary of dimensions, size and size variations, and runout errors.
● Symbols for bearing dimensions and accuracy
| Basic Dimensions | Dimentional Accuracy | ||
|
d D B C r |
= Basic bore diameter = Basic outside diameter = Basic inner ring width = Basic outer ring width = Chamfer of inner ring and outer ring |
Δdmp |
= Single plane mean bore diameter deviation from basic |
| ΔDmp |
= Single plane mean outside diameter deviation from basic |
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| ΔBs |
= Single inner ring width deviation from basic |
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| ΔCs |
= Single outer ring width deviation from basic |
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| Dimentional Variaties | Running Accuracy | ||
|
Vdmp VDmp VBs VCs |
= Mean bore diameter variation = Mean outside diameter variation = Inner ring width variation = Outer ring width variation |
Kia |
= Radial runout of assembled bearing inner ring |
| Kea |
= Radial runout of assembled bearing outer ring |
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| Sia |
= Axial runout of assembled bearing inner ring |
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| Sea |
= Axial runout of assembled bearing outer ring |
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| Sd |
= lnner ring reference face runout with bore |
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| SD |
= Outside cylindrical surface runout with outer ring reference face |
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