Overview
ISO 3031:2021 - "Rolling bearings - Thrust needle roller and cage assemblies, thrust washers - Boundary dimensions, geometrical product specifications (GPS) and tolerance values" - defines the boundary dimensions, GPS-compliant geometric specifications and tolerance values for thrust needle roller and cage assemblies and recommends dimensions and tolerances for thrust washers (shaft or housing washers). This fourth edition implements the ISO/GPS system and replaces the earlier edition; it also includes informative annexes on application characteristics and functional gauging.
Key topics
- Boundary dimensions and tolerances: Tabulated limits for thrust needle roller and cage assemblies (Table 2) and thrust washers (Table 3).
- Geometrical Product Specifications (GPS): Application of the ISO/GPS system (ISO 8015 matrix model) and dimensional tolerancing rules (ISO 14405‑1) to bearing geometry.
- Needle roller tolerances: Needle roller tolerances and gauges are referenced to ISO 3096.
- Gauging and functional measurement: Annex B describes GO/NOGO and plug/ring gauge principles for verifying bore and outside diameters and explains differences between assemblies and washers.
- Application guidance: Annex A gives suggested characteristics for mounting surfaces (hardness, flatness, perpendicularity and support considerations) and advises consulting manufacturers for specific recommendations.
- Normative references and measurement uncertainty: References include ISO 5593 (vocabulary), ISO 14405‑1, ISO 1132‑2 (measuring technique), and guidance on decision rules (ISO 14253‑1/2).
Practical applications
- Ensures consistent interchangeability and quality control for axial (thrust) needle-roller bearings used in transmissions, automotive components, industrial gearboxes, and rotating machinery where compact thrust support is required.
- Used by designers and mechanical engineers to specify correct boundary dimensions, tolerances and GPS annotations on drawings and CAD models.
- Used by manufacturing, inspection and quality teams for production acceptance, gauging procedures and functional verification of bearing components.
- Valuable for procurement and standards compliance to confirm supplied thrust washers and cage assemblies meet international dimensional and tolerance requirements.
Who should use this standard
- Mechanical designers and bearing engineers specifying thrust needle roller assemblies and thrust washers.
- Production and quality engineers responsible for machining, assembly and inspection/gauging.
- Bearing manufacturers, component suppliers and testing laboratories ensuring conformity to GPS and tolerance classes.
Related standards
Keywords: ISO 3031:2021, thrust needle roller and cage assemblies, thrust washers, boundary dimensions, GPS, tolerances, gauging, ISO 3096.
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