Overview
ISO 20515:2021 - Rolling bearings - Radial bearings, retaining slots - Dimensions, geometrical product specifications (GPS) and tolerance values - defines the dimensional and geometrical requirements for retaining slots used in the outer rings of specific radial bearings. The standard applies to outer rings of:
- single-row angular contact ball bearings
- four‑point‑contact ball bearings
- radial cylindrical roller bearings (specified dimension series)
It does not apply to outer rings of sealed/shielded radial ball bearings or cylindrical roller bearings without ribs.
Key topics
- Scope and definitions: clear definitions for terms such as retaining slot, nominal width, position specifications (PS1, PS2), fillet radius r0 and nominal outside diameter D.
- GPS-based specifications: dimensions and tolerances are given within the Geometrical Product Specification (GPS) framework (ISO 8015 matrix model), including how to indicate characteristics on drawings.
- Dimension tables: tabulated nominal dimensions and permissible tolerance values for specified diameter and dimension series (e.g., diameter series 0, 2, 3, 4 and certain cylindrical roller dimension series).
- Position and tolerance rules: position specifications for the bottom surface (PS1) and median plane(s) (PS2), size deviation notations (Δbg, Δbs) and symbol conventions (ISO/TC 4 formatting, leading “t” prefix for tolerance symbols).
- Fillet radius guidance: lower limit for r0 should not be zero - minimum fillet recommended to avoid stress concentrations; expressed as tolerance values (e.g., r0 max).
- Illustrations and examples: Figures show bearings with one or two diametrically opposed retaining slots; Annex A (drawing examples) and Annex B (application example) support implementation.
- Normative references: links to complementary GPS and bearing standards (ISO 15, ISO 1101, ISO 14405-1, ISO 5593, ISO 15241, ISO 22872).
Applications
ISO 20515:2021 is practical for:
- bearing design and manufacturers specifying retaining slot geometry on outer rings
- mechanical designers and machine builders who prevent outer-ring rotation using retaining slots
- quality, metrology and inspection teams applying GPS tolerancing and measurement uncertainty
- procurement and engineering teams creating component drawings and acceptance criteria
- CAD modelers and drafting engineers who need standardized drawing indications and tolerance symbols
Using this standard ensures interchangeability, reduces fitting/assembly issues and improves component reliability where outer-ring anti-rotation features are required.
Related standards
Keywords: ISO 20515:2021, rolling bearings, retaining slots, radial bearings, dimensions, tolerances, GPS, outer ring, angular contact ball bearings, cylindrical roller bearings.