Overview
EN ISO 22751:2020 - Rubber or plastic coated fabrics - Determination of bending force specifies a standardized laboratory method to measure the bending force (flexibility) of rubber- or plastic-coated fabrics. The test uses the bar (two‑point) method: a specimen clamped in a rotating fixture is bent against a vertical metering bar and the force exerted at a specified bending angle is recorded. This standard supports repeatable evaluation of coated-fabric flexibility for quality control, specification and R&D.
Key Topics and Technical Requirements
- Test principle: Bar method / two‑point bending - specimen rotates about a pivot and presses against a vertical bar; force measured at defined angle(s).
- Apparatus:
- Clamping jaws: depth (35 ± 1) mm, minimum width ≥ 30 mm; parallel clamping with controlled pressure.
- Pivot and rotation: pivot axis at front edge of fixed clamp (±0.1 mm); rotation range 1°–91° with max deviation 1.5 %; rotational speed adjustable up to 10°/s (accuracy 0.1°/s).
- Force measurement: load cell capacity up to 10 N (optionally 1 N for very flexible materials) meeting ISO 7500‑1 class 2 accuracy; vertical bar with sharp edge (R = 0.05 mm ± 0.01 mm) and width ≥ 30 mm.
- Adjustable bending length: 0.1 mm to 50 mm (accuracy ≥ 0.1 mm); preliminary contact force adjustable (accuracy at least 1 mN).
- Torque wrench for clamping: range 0.05–0.2 Nm with 0.01 Nm accuracy.
- Sampling and specimen preparation:
- Minimum three specimens cut longitudinally and three perpendicular to manufacture direction; additional sets if testing both faces.
- Mark the side that extends during testing.
- Conditioning and atmosphere:
- Use atmospheres per ISO 2231. Minimum conditioning: 16 h for one‑sided coated fabrics, 24 h for both‑sided.
- Testing atmosphere selected from ISO 2231 atmospheres A–E (commonly 23 °C / 50 % RH in temperate regions).
- Data and reporting:
- Measure bending force at defined angles; report test parameters, raw data and specimen orientation.
Applications - Who Uses This Standard
- Manufacturers of rubber- or plastic-coated fabrics for tarpaulins, inflatable structures, upholstery, protective clothing, industrial covers and technical textiles.
- Independent testing laboratories and quality control departments validating flexibility, conformity and batch consistency.
- Product designers and R&D teams comparing materials or optimizing coatings for bending performance.
- Procurement and certification bodies requiring standardized test evidence in specifications and contracts.
Related Standards
- ISO 2231:1989 - Standard atmospheres for conditioning and testing
- ISO 2286‑3 - Determination of thickness (roll characteristics)
- ISO 7500‑1 - Calibration and verification of force-measuring systems
Keywords: EN ISO 22751:2020, bending force test, rubber coated fabrics, plastic coated fabrics, bar method, coated fabrics testing, flexibility testing, textile testing.