ISO 7148-1:2025

Overview

ISO 7148-1:2025 - Plain bearings: Testing of the tribological behaviour of bearing materials - Part 1: Testing of bearing metals specifies standardized tribological tests for metallic plain bearing materials under boundary lubrication. The fourth edition updates test methods, specimen definitions and reporting requirements to help compare friction and wear behaviour of bearing material / mating part / lubricant combinations for low-speed, continuous-sliding applications.

Key topics

• Scope and purpose
  • Defines tests targeted at metallic bearing materials used in plain bearings when hydrodynamic film separation cannot be guaranteed (boundary lubrication).
• Test methods
  • Pin-on-disc (vertical and horizontal arrangements) - basic tribological screening and simulation of linear guidance systems.
  • Block-on-ring - plane or conformal block contact for material ranking.
  • Rotation under thrust load - sleeve-to-sleeve and sleeve-to-plate configurations for continuous sliding.
• Test specimens
  • Standard geometries covered include disc, ring, pin, block, sleeve and plate; preparation and dimensions are specified.
• Measured outputs and symbols
  • Friction force/coefficient of friction, linear and volumetric wear rates, wear volumes, surface parameters and temperatures (see Table 1).
• Test conditions and lubrication
  • Emphasis on reproducing boundary-lubrication conditions (low speed, high load, start/stop scenarios) and documenting lubricant properties and temperatures.
• Test procedure and reporting
  • Detailed procedures, equipment requirements and a standardized test report format (new Clause 13 and informative Annex A).
• Comparability considerations
  • Notes that results depend strongly on test parameters; meaningful comparisons require identical test setups and conditions.

Applications

• Material selection and ranking for plain bearings exposed to boundary lubrication (e.g., start/stop engines, oscillating pivots, slow-speed journal bearings).
• R&D and qualification testing of bearing alloys and surface treatments.
• Supplier and OEM performance verification and lifecycle wear assessment.
• Tribology laboratories performing standardized friction and wear testing to support product development and failure analysis.

Who uses this standard

• Bearing manufacturers and designers
• Materials engineers and tribologists
• Test laboratories and certification bodies
• OEMs specifying bearing performance for machinery, automotive, marine and industrial equipment
• Maintenance engineers evaluating retrofit or replacement materials

Related standards

• ISO 4378-2 - Plain bearings: Terms, definitions, classification and symbols - Part 2: Friction and wear
• ISO 4378-3 - Plain bearings: Terms, definitions, classification and symbols - Part 3: Lubrication
• Full list of ISO 7148 series parts available on the ISO website

Using ISO 7148-1:2025 ensures consistent, comparable tribological testing of metallic plain bearing materials and supports reliable material selection for boundary-lubricated applications.