Overview
ISO 20876:2018 is an international standard published by the International Organization for Standardization (ISO) that specifies test methods for evaluating the resistance of footwear insoles to stitch tear. This standard applies to insoles made from any material and assesses their ability to hold stitches or withstand clenched metal fastenings. The test method described in ISO 20876:2018 has become widely accepted as a quality criterion, including for insoles attached using adhesives.
Key Topics
- Scope: The standard outlines a procedure to determine the force required to pull a wire loop through an insole material, measuring stitch tear resistance.
- Sampling and Conditioning: Test pieces are cut from the insole or component, typically sized 75 mm by 25 mm, and conditioned under standardized atmospheric conditions to ensure consistent testing environments.
- Test Apparatus: Essential equipment includes a tensile testing machine compliant with ISO 7500-1, a drilling jig, a specific drill bit, steel wire loops formed over a mandrel, and a dial micrometer gauge for thickness measurement.
- Test Procedure: The insole specimens are drilled with pairs of holes and a steel wire loop is threaded through these holes. The tensile testing machine pulls the wire loop until the material fails, recording the maximum force. This procedure is repeated in principal directions for reliability.
- Results and Reporting: The stitch tear resistance is expressed as the average maximum force in newtons, alongside the average thickness of each test piece. The test report includes references to ISO 20876:2018, sample description, testing conditions, and any deviations from the method.
Applications
- Footwear Quality Control: Manufacturers use ISO 20876:2018 to verify the durability and quality of insole materials in various types of footwear.
- Material Comparison: The standardized test enables comparison of stitch tear resistance across different insole materials, helping in material selection and design optimization.
- Product Development: During prototyping, this standard guides the evaluation of attachment methods (stitched or adhesively bonded insoles) to ensure long-lasting performance.
- Compliance and Certification: Complying with ISO 20876:2018 supports footwear brands in meeting international quality standards and consumer expectations.
Related Standards
- ISO 7500-1 – Calibration and verification of static uniaxial testing machines, critical for ensuring accurate tensile force measurements in stitch tear tests.
- ISO 17709 – Sampling, preparation, and conditioning of footwear samples, providing protocols for consistent test specimen preparation.
- ISO 18454 – Standard atmospheres for conditioning footwear and components, establishing controlled environmental conditions for sample testing.
Keywords: ISO 20876:2018, footwear testing, insole testing, stitch tear resistance, footwear quality standards, tensile testing, insole materials, footwear manufacturing standards, durability testing, ISO footwear standards.
