ISO 7148-1:2012

Overview

ISO 7148-1:2012 - 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 standard defines repeatable test procedures to compare friction and wear behaviour of bearing material / mating material / lubricant combinations, enabling informed material selection for low-speed, continuous sliding or repeated operation where hydrodynamic lubrication cannot be guaranteed.

Key topics and requirements

• Scope and limitations
  • Tests are for metallic bearing materials under boundary lubrication and low sliding speed; results are comparable only when all influencing parameters are identical. Variability between test facilities is explicitly noted.
• Test methods
  • Method A - Pin-on-disc
  • Method B - Block-on-ring
  • Method C - Rotation under thrust load (sleeve-to-sleeve, sleeve-to-plate)
  • Tests require equipment for continuous measurement of friction and wear.
• Test specimens and preferred dimensions
  • Disc: diameter 40–110 mm, width 8–12 mm.
  • Ring: outside diameter 40–80 mm.
  • Pin: diameter 3–10 mm.
  • Block: cross-section 5–10 mm (height and width).
  • Sleeve and plate dimensions given (machined specimens).
• Specimen preparation
  • Machining to application-representative surface finish, cleaning steps (example: alcohol ultrasonic bath, hot-air drying, hexane rinse, drying at 110 °C).
• Test conditions and variables to control
  • Initial surface roughness (Ra), normal force (Fn), lubricant temperature (TL), sliding distance, sliding velocity (U), and overlap ratio (K).
  • Specific-load guidance: up to about one third of the material’s proof stress or compression limit (as per ISO 4385) for heavily loaded comparisons.
• Lubrication
  • Oil or grease as appropriate; full contact lubrication filling recommended (immersion preferred for oil). Oil temperature must be controlled; lubricant choice strongly affects outcomes.
• Designation
  • Example: “Test ISO 7148-1 -A” for pin-on-disc testing.

Applications and users

• Practical use:
  • Selecting metallic bearing materials for plain bearings operating under boundary lubrication, low speed, or frequent starts/stops.
  • Comparative lab evaluation of material/mating/lubricant combinations and wear-rate prediction under controlled conditions.
• Typical users:
  • Tribologists, bearing designers, materials engineers, OEMs, test laboratories, and quality/receiving inspection teams involved in bearing selection, development and certification.

Related standards

• ISO 7148-2 (Part 2: polymer-based bearing materials) - companion document for non-metallic bearings.
• ISO 4385 - referenced for compression testing and material limits used in load selection.

Notes: ISO 7148-1:2012 provides test method selection, specimen specs and strict control of variables to produce comparable friction and wear data. When applying results to real-world designs, ensure test parameters closely match the intended service conditions to reduce uncertainty.