Overview - EN ISO 9073-7:2024 (Nonwovens - Determination of bending length)
EN ISO 9073-7:2024 / ISO 9073-7:2024 is the international/CEN-adopted test method for measuring the bending length of nonwoven textiles and for deriving flexural rigidity from that measurement. Approved by CEN in November 2024, this standard defines a repeatable laboratory procedure specific to nonwovens (not applicable to combination-type materials such as composites or laminates that exhibit natural twist).
Key topics and technical requirements
- Scope and purpose: Specifies a method to determine bending length and a formula to calculate flexural rigidity (expressed in mN·cm). Useful for assessing stiffness and handle of nonwovens.
- Principle: A rectangular strip is advanced over a horizontal platform until its free overhang reaches a plane inclined 41.5° below horizontal; the overhanging length at that point equals twice the bending length.
- Test specimens:
- Size: (25 ± 1) mm × (250 ± 1) mm.
- Orientation: Six specimens in the machine direction (MD) and six in the cross-machine direction (CD); production control may use three per direction.
- Conditioning: Per ISO 139 standard atmospheres; specimens should be free of creases and taken at least 50 mm from sample edges.
- Apparatus highlights:
- Platform: (40 ± 2) mm wide × (200 ± 2) mm long, supported ≥150 mm above the table with marked 41.5° lines on supports. PTFE surface recommended to prevent sticking.
- Steel rule: ~25 mm wide, ~350 mm long, mass ~250 g (±10 g), rubber underside; graduated in mm.
- Timing and controlled rule advancement (typical rate ~25 mm in 5 s); read overhang after (8 ± 2) s.
- Results and units: Bending length (mm) and derived flexural rigidity (mN·cm). Mass per unit area should be determined (ISO 9073-1) before testing.
Practical applications and users
- Who uses it: Textile test laboratories, nonwoven manufacturers, R&D teams, quality control, product engineers, procurement and compliance officers.
- Why it matters:
- Quality control of stiffness and handle for hygiene, medical, filtration, automotive, geotextile and consumer nonwovens.
- Material selection and product specification when bending behavior affects performance or user perception.
- Comparative testing in product development and supplier evaluation.
Related standards
- ISO 9073-1 (mass per unit area for nonwovens)
- ISO 139 (conditioning atmospheres for textiles)
- ISO 186 (sampling to determine average quality)
EN ISO 9073-7:2024 provides a standardized, reproducible method to quantify nonwoven bending behavior and convert it into a mechanical stiffness parameter (flexural rigidity) for both quality assurance and design decisions.
