Overview
ISO 3548-1:2022 - Plain bearings: Thin-walled half bearings with or without flange - Part 1 specifies tolerances, design features and test methods for thin-walled half bearings used predominantly in reciprocating machinery. The standard covers half bearings with integral flanges up to an outside diameter Do = 250 mm and without flanges up to Do = 500 mm. All dimensions and tolerances are given in millimetres. This second edition (2022) updates symbols, figures and normative references to reflect current measurement and manufacturing practice.
Key topics and technical requirements
- Scope & limits: Flanged half bearings ≤ 250 mm outside diameter; non‑flanged ≤ 500 mm. Dimensions are flexible and peripheral length is measured rather than direct outside diameter.
- Tolerances: Specified for crush height, wall thickness and widths - tolerances differ for “as‑machined” versus “as‑plated” bearing bores. Housing diameter manufacturing tolerance recommended as H6 (ISO 286‑2).
- Measurement methods: Peripheral length measured with special checking fixtures; two checking methods (A and B) and procedures for calculating the effective test force F are defined.
- Design features: Guidance on locating nicks and recesses, reliefs and chamfers, transition between radial part and flange, assembled flange toes, oil grooves and oil holes, and permissible surface roughness of sliding surfaces.
- Eccentric bores: Accepts eccentric (crowned) bore designs; eccentricity controlled via a specified wall‑thickness reduction u measured at defined angles/points.
- Assembled flange function: Test data and classification for assembled flange bearings including axial width checks and checklist items to ensure correct function under load.
- Units and symbols: Complete symbol table and diagrams for dimensions such as a (crush height), s (wall thickness), B (width), P (free spread), and Ra (surface roughness).
Applications and users
- Who uses it: Mechanical designers, plain bearing manufacturers, OEMs of reciprocating engines and compressors, quality/control engineers, test laboratories and procurement/specification writers.
- Practical uses:
- Specify and verify bearing components for reciprocating machinery.
- Ensure correct interference fit and housing tolerances (H6) for reliable service.
- Define inspection and test procedures for peripheral length, crush height and assembled flange performance.
- Guide layout of oil grooves, locating nicks and chamfers to optimize function and assembly.
Related standards
- ISO 3548-3 - Measurement of peripheral length for thin-walled half bearings
- ISO 6526 - Pressed bimetallic half thrust washers - features and tolerances
- ISO 21920-3 - Surface texture (profile) - specification operators
Practical takeaway: ISO 3548-1:2022 is the authoritative reference for designers and manufacturers of thin‑walled half bearings, providing standardized tolerances, mandatory testing approaches and design guidance to ensure interchangeability and reliable operation in reciprocating machinery. Keywords: ISO 3548-1:2022, thin-walled half bearings, plain bearings, tolerances, test methods, flanged half bearings, crush height, peripheral length.