Overview
ISO 252:2023 - "Conveyor belts - Adhesion between constitutive elements - Test methods" defines standardized laboratory procedures to measure the adhesion strength between the components of a conveyor belt (plies, covers and carcass). The standard specifies two alternative test methods (Method A and Method B), basic test conditions aligned with ISO 36, and reporting requirements. ISO 252:2023 applies to most conveyor belting constructions except belts with steel‑cord reinforcement and textile‑reinforced belts with full‑thickness tensile strength below 160 N/mm. It is not suitable for light conveyor belts covered by ISO 21183‑1.
Key topics and technical requirements
- Test methods: Two options - Method A and Method B. Both use a constant‑rate tensile (strip) test; results from the two methods can differ and manufacturers’ guidance is recommended.
- Apparatus: Power‑driven tensile testing machine conforming to ISO 36; autographic recording of force during stripping.
- Test pieces:
- Rectangular strips, (25 ± 0.5) mm wide, minimum 200 mm length (allowing ≥100 mm to be stripped).
- Minimum two longitudinal test pieces; optionally two transverse pieces if agreed.
- Test pieces taken ≥100 mm from belt edges and widely spaced.
- Conditioning and timing:
- Time between manufacture and testing ≥16 hours (including conditioning).
- Conditioning in accordance with ISO 18573 (atmosphere D or E), with tests immediately after conditioning.
- Procedure details:
- Strip components from one end, recording force at a traverse rate of (100 ± 10) mm/min.
- Method A: sequentially strip individual plies/covers toward midline.
- Method B: strip pairs of plies (two unseparated plies) in sequence.
- Result analysis:
- Multi‑peak traces analysed per ISO 6133.
- Median peak force specified as mean adhesion force; lowest recorded peak as minimum adhesion.
- Adhesion expressed as N/mm (to 0.1 N/mm), calculated from force divided by strip width.
- Reporting: Report must reference ISO 252:2023 and include belt ID, manufacture-to-test intervals, conditioning conditions, method used (A or B), mean/minimum adhesion values (top/bottom cover and ply‑to‑ply), deviations, observations and test date.
Applications and users
- Who uses it: Conveyor belt manufacturers, materials test laboratories, quality control teams, purchasers and engineers specifying belting for mining, bulk handling, ports, quarries and industrial conveyor systems.
- Practical value:
- Verifies bond integrity between covers, plies and carcass to predict in‑service delamination risk.
- Supports acceptance testing, quality assurance, failure analysis and product development.
- Provides comparable adhesion data for procurement and contractual specifications.
Related standards
- ISO 36 - Rubber - Determination of adhesion to textile fabrics (test machine requirements)
- ISO 6133 - Analysis of multi‑peak traces for tear and adhesion tests
- ISO 18573 - Conveyor belts - Test atmospheres and conditioning periods
- ISO 21183‑1 - Light conveyor belts (reference for exclusions)
Keywords: ISO 252:2023, conveyor belts, adhesion strength, adhesion test methods, Method A, Method B, ISO 36, ISO 6133, ISO 18573, ply adhesion, cover adhesion.