Overview
ISO 22423:2019 specifies a standardized method for performance testing of foil thrust bearings that operate with air (or gas) lubrication. The standard defines how to measure and compare static load capacity, bearing torque, friction coefficient, take-off speed and lifetime using controlled test apparatus and repeatable start–stop cycles. It addresses bearings that generate aerodynamic load by shaft rotation and removes the need for oil lubrication, making it relevant for high-speed, oil-free turbomachinery.
Key Topics and Requirements
- Scope and purpose: Procedures to measure and evaluate the primary performance metrics of foil thrust bearings and to compare results under different test conditions.
- Test environment: Tests are carried out after ambient pressure, temperature and humidity reach equilibrium; preheating and steady-state conditions are required.
- Test apparatus design: Emphasis on accurate alignment and controlled relative position of runner and bearing to avoid measurement errors caused by misalignment or disturbance.
- Sensors and instrumentation: Installation of torque measurement, load cells, rotational speed meters and thermocouples (air and top-foil surface) as detailed in the document.
- Start–stop cycles and take-off speed: Determination of the speed at which the runner lifts off the top foil (take-off) from measured torque vs. speed behavior.
- Reference and initial loads: Recommended thrust pressure for reference load is 0.5 bar (0.05 N/mm²); reference load Fr = thrust pressure × top-foil area. Initial load and increments typically set as percentages of Fr.
- Calculations and reporting: Procedures for calculating bearing torque, load, friction coefficient and evaluating static load capacity per unit area; format and essential items for the test report (Annex B).
- Durability and lifetime: Start–stop durability tests with lifetime defined by number of cycles until coating layer disappearance; methods outlined in Clause 9.
Applications and Users
ISO 22423 is practical for:
- Bearing manufacturers validating foil thrust bearing designs
- R&D and test laboratories performing comparative performance testing
- OEMs of turbines, compressors, pumps and other high-speed rotating machinery specifying oil-free bearing performance
- Maintenance engineers and quality control teams verifying lifetime, friction and load capacity for procurement and certification
Keywords: ISO 22423, foil bearings, foil thrust bearings, static load capacity, bearing torque, friction coefficient, lifetime testing, take-off speed, performance testing.
Related Standards
- Prepared by ISO/TC 123 (Plain bearings). Users commonly apply ISO 22423 alongside other ISO plain-bearing test and design documents and the ISO/IEC Directives for standardization practices. Refer to the standard text (Annex A/B) for typical bearing configuration and recommended test-report contents.
Open preview (PDF)Foil bearings — Performance testing of foil thrust bearings — Testing of static load capacity, bearing torque, friction coefficient and lifetime
