Overview - EN ISO 17706:2018 (Footwear uppers tensile test)
EN ISO 17706:2018 (adoption of ISO 17706:2003) is a CEN standard that specifies a laboratory test method for determining the force required to break test specimens taken from footwear uppers, regardless of material. The method measures both breaking strength (N/mm) and tensile elongation (%), providing objective data to assess upper material suitability for end use.
Key topics and technical requirements
- Scope: Uppers including complete upper assemblies (visible outer materials); excludes toe puffs and stiffeners.
- Specimen geometry:
- Length: 160 mm ± 10 mm.
- Width: materials that can fray - cut to 35 mm ± 2 mm, then remove threads to reduce to 25.0 mm ± 0.5 mm; non-fraying materials - 25 mm ± 0.5 mm.
- Six specimens: three along (longitudinal) and three across (transverse) the material.
- Conditioning and sampling:
- Avoid seams/perforations when cutting specimens.
- Condition specimens in a standard atmosphere per EN 12222 for at least 48 hours before testing.
- For leather sampling, refer to prEN 12987 for butt/side selection and backbone direction.
- Apparatus:
- Tensile testing machine with jaw separation rate 100 mm/min ± 5 mm/min and initial jaw gap 100 mm ± 1 mm.
- Force-measuring accuracy better than 2% (machine class 2 per EN ISO 7500‑1). Typical force ranges: <1 kN for textiles/coated textiles; up to ~5 kN for thick leather (>2 mm).
- Cutting tool (press knife), and distance measuring device (accuracy 0.5 mm).
- Test procedure & acceptance:
- Clamp specimen with 100 mm gauge length; pull until failure.
- Reject results if specimen slips >2 mm in jaws or fails within 5 mm of a jaw (with exceptions noted).
- Record breaking force (F) and elongation at break (E).
- Calculations:
- Breaking strength = F (N) / specimen width (mm) → N/mm.
- Tensile elongation (%) = (E / GL) × 100, where GL is initial jaw separation (mm).
- Reporting: Include mean breaking strength and mean tensile elongation for each test direction plus test conditions and specimen details.
Applications - who uses this standard
- Footwear manufacturers and component suppliers for material selection and quality control.
- Independent testing laboratories for compliance and comparative performance testing.
- Product development and R&D teams evaluating new upper materials or constructions.
- Procurement and specification writers who require objective tensile strength/elongation data.
Related standards
- EN 12222 - standard atmospheres for conditioning/testing footwear.
- EN ISO 7500‑1 - verification/calibration of tensile testing machines.
- EN 13400 - sampling location and conditioning of samples.
- prEN 12987 - leather sampling guidance.
- ISO 17706:2003 - original international text adopted as EN ISO 17706:2018.
Keywords: EN ISO 17706:2018, footwear, uppers, tensile strength, elongation, test method, breaking strength, tensile testing machine, conditioning, sampling.
