ISO 17694:2016

Overview

ISO 17694:2016 - Footwear - Test methods for uppers and lining - Flex resistance specifies a laboratory test method to determine the flex resistance of footwear uppers and linings irrespective of material. The method assesses a material’s tendency to crack, crease, flake or develop salt spue under repeated bending (flexing) to help judge suitability for end use. The procedure simulates the inward folding of a shoe vamp and can be performed in dry, wet or sub-zero conditions.

Key technical topics and requirements

• Test principle: Rectangular specimens are folded and clamped in a flexing machine (flexometer) so that inward and vertical folds are repeatedly flexed through a defined angle. Damage is visually assessed at set cycle intervals.
• Apparatus and parameters:
  • Flexing angle: 22°30' ± 0°30';
  • Oscillation speed: 100 ± 5 cycles/min;
  • Distance between clamps (horizontal position): 25 ± 1 mm;
  • Specimen press knife size typically 70 × 45 mm; specimen length must be 70 ± 1 mm.
• Conditioning and environments:
  • Tests may be conducted dry, wet (using deionised water and vacuum impregnation) or cold (e.g., around –5 °C; lower temperatures may be used).
  • Conditioning follows referenced atmospheres (see Related Standards).
• Sampling and orientation:
  • Specimens are cut along and across the material’s backbone/warp directions; for uppers specimens should be taken from the forepart at the point of greatest flexing.
  • Test direction: uppers tested face up, linings face down.
• Inspection stages:
  • Recommended inspection cycle points include 1 000, 2 000, 5 000, 10 000, 25 000, 50 000 and 100 000 cycles (applicability varies by dry/wet/cold).
• Assessment criteria:
  • Record creasing, visible or fine cracks (with magnifier), loss of adhesion, greying, powdering/flaking, broken yarns (textiles), and salt spue grading (light/marked/heavy).

Practical applications and users

• Who uses it: footwear manufacturers, material suppliers, independent testing laboratories, R&D and QA teams, product developers and certification bodies.
• Typical uses:
  • Compare flex durability of leathers, coated fabrics, textiles and lining materials.
  • Support material selection and design decisions for durability and end-use performance.
  • Quality control and batch verification to detect manufacturing or coating failures.
  • Failure analysis (cracking, adhesion loss, salt spue) to drive corrective actions.

Related standards

• ISO 5402-1:2011 - Determination of flex resistance (flexometer method)
• ISO 17709 - Sampling location and conditioning of footwear test pieces
• ISO 18454 - Standard atmospheres for conditioning and testing
• ISO 3696 - Water for analytical laboratory use

Keywords: ISO 17694:2016, flex resistance, footwear testing, uppers and lining, flexometer, durability testing, salt spue, material selection, quality control.