ISO 6281:2020

Overview

ISO 6281:2020 - "Plain bearings - Testing under conditions of hydrodynamic and mixed lubrication in test rigs" defines requirements for laboratory testing of lubricated plain journal bearings (solid and multi‑layer) under hydrodynamic and mixed lubrication regimes. Intended primarily for bearing and material development, the standard specifies how test rigs, test procedures, measuring equipment, lubricant supply and operating conditions should be arranged so test results (wear, friction, load capacity, temperature, etc.) are reproducible and comparable. It explicitly excludes testing of dynamic lubricant‑film characteristics used for turbo‑rotor vibration and stability calculations.

Key topics and technical requirements

• Scope and applicability: Tests for plain journal bearings under static and dynamic loading during development; not for rotor dynamic film‑characteristic studies.
• Test objectives: The standard lists target properties to measure, including:
  • running‑in ability, wear resistance, material compatibility (adhesion)
  • embeddability, resistance to scoring/abrasion, conformability, deformability
  • erosion resistance (cavitation, fluid, particle), static and dynamic load carrying capacity
  • friction characteristics, lubricant flow rate, temperature increase
• Test rigs and setup: Recommendations for rig design to simulate relevant parameters (bearing geometry, load, speed, lubricant supply) and generic rig types suitable for journal bearing testing.
• Test procedures: Guidance for running‑in tests, wear testing, adhesion/compatibility, embeddability, fatigue (dynamic load capacity), and friction/temperature evaluations.
• Measurements and reporting: Requirements for measuring independent/dependent variables, instrument calibration, test bearing and journal specification, lubricant properties and supply method, operating conditions, and standardized test reports.
• Hydrodynamic variables: Emphasis on viscosity, speed, load per unit width (ηU/F*), thermo‑elastohydrodynamic effects and their influence on test outcomes.

Applications and users

ISO 6281 is used by:

• Bearing manufacturers and designers for material selection and product development
• Tribologists and test engineers conducting laboratory evaluation of journal bearings
• Lubricant formulators assessing compatibility and film performance
• Research labs, automotive, aerospace, power generation and industrial machinery teams validating bearing performance under mixed/hydrodynamic regimes

Practical uses include benchmarking wear resistance, validating static/dynamic load capacity, optimizing lubricant supply methods, and comparing material combinations under controlled rig conditions.

Related standards

• ISO 4378 (all parts) - referenced for terms, definitions, classification and symbols used in plain bearing testing.
• ISO 6281:2020 replaces the 2007 edition; consult national bodies for implementation details and any test method extensions.

Keywords: ISO 6281:2020, plain bearings, hydrodynamic lubrication, mixed lubrication, test rigs, journal bearings, bearing testing, wear resistance, load carrying capacity, tribology.