Overview
ISO 7544:2024 - Rolling bearings - Test and assessment methods for cleanliness - defines standard procedures, equipment and assessment techniques for cleanliness inspections of rolling bearings. Published in 2024, this ISO document applies to open and capped bearings (before grease filling) and to individual rolling bearing parts. It is specifically tailored to bearing components and is not applicable to linear motion rolling bearings. ISO 7544 provides a consistent framework to extract, filter, measure and report particulate contamination to enable comparable cleanliness results across suppliers and test laboratories.
Key topics and technical requirements
- Scope and terminology: Defines component and rolling bearing part terms, controlled surfaces, and the concept of an extraction curve measurement.
- Equipment and extraction methods: Specifies equipment for two primary extraction techniques:
- Pressure-rinsing method (parameters and procedure are prescribed)
- Ultrasonic extraction method (bath sizing, power density and procedure)
- Filtration and drying: Requirements for selection and handling of analysis filters, filtration procedures and drying prior to analysis.
- Analysis methods:
- Gravimetry (residue mass measurement)
- Light-optical analysis (particle counting and morphology)
- Measurement metrics and codes: Introduces the Component Cleanliness Code (CCC) and other symbols/abbreviations used to quantify particle loads per controlled surface area.
- Quality control procedures: Includes blank-value determination, test-lot specification, repeatability via extraction curve measurements and an escalation strategy for non-conforming results.
- Documentation and safety: Test report requirements and informative annexes covering occupational health, safety and example reports.
Practical applications - who uses ISO 7544
ISO 7544 is intended for:
- Bearing manufacturers and suppliers conducting incoming/outgoing cleanliness inspections
- Third‑party test laboratories and quality assurance teams validating bearing cleanliness
- OEMs and procurement teams specifying cleanliness requirements in contracts
- Maintenance and reliability engineers assessing failure modes related to particulate contamination
Benefits include standardized test methods, reproducible contamination data for supplier control, and clearer communication of cleanliness requirements between customers and suppliers.
Related standards
- ISO 16232:2018 (road-vehicle component cleanliness) - ISO 7544 adapts concepts from ISO 16232 specifically for rolling bearings.
- ISO 5593:2023 (rolling bearings - vocabulary) - provides terminology used in ISO 7544.
- ISO 281 (bearing life calculation) is referenced as context for cleanliness impact on bearing performance.
Keywords: ISO 7544, rolling bearings, cleanliness inspection, pressure-rinsing, ultrasonic extraction, filtration, gravimetry, light-optical analysis, component cleanliness code (CCC).