Overview
EN ISO 19958:2004 - Footwear - Test methods for heels and top pieces - Top piece retention strength (ISO 19958:2004) defines a laboratory test to measure the force required to detach the top piece (heel cap) from the underside of a shoe heel. The method applies to heels with the top piece already attached (removed from complete shoes), to heels alone with the top piece attached, and in some cases to push‑in top pieces. Exceptions include reinforced slender heels attached by steel spigots and built stacked heels.
Key topics and technical requirements
- Test principle: A steadily increasing tensile force is applied perpendicular to the top piece/heel interface until the top piece is detached. The maximum force (in Newtons) and any initial peak force are recorded.
- Apparatus:
- Tensile testing machine complying with EN ISO 7500‑1 class 2, range 0–1000 N.
- Specified rate of force application: 15 N/s ± 5 N/s (or equivalent traverse adjusted to produce this rate).
- Drill bits, bolts (M4 or M3 for slender heels), washers, nuts, rods (2 mm) or strong extensible cords.
- Specimen preparation:
- Different preparation for medium/high heels versus low heels (cutting stem, drilling vertical hole in top piece, drilling horizontal holes in heel stem).
- For push‑in top pieces, attach in the lab using production-equivalent methods (pneumatic insertion, correct nails or staples where used).
- Procedure:
- Attach bolt through top piece to upper jaw; secure heel to lower jaw via rod(s) or cords.
- Apply force until detachment; record maximum and initial peak forces.
- Repeat for a set of specimens (procedure indicates testing several assemblies and reporting individual results).
- Results and reporting:
- Report maximum pull‑off force (N) and initial peak (if present), describe failure modes and positions.
- Include full sample description, reference to EN ISO 19958, and test date.
Applications and users
- Footwear manufacturers and product designers: verify heel top piece retention during development and before production release.
- Quality control and inspection labs: routine batch testing and supplier acceptance testing to maintain consistency and durability.
- Third‑party testing laboratories: certification, comparative testing, and failure analysis.
- Procurement and compliance teams: evaluating supplier claims and ensuring product reliability and consumer safety.
Practical uses include durability verification, specification setting, supplier audits, and root‑cause analysis of heel detachment complaints.
Related standards
- EN ISO 7500‑1 (Metallic materials - Verification of static uniaxial testing machines) - referenced for tensile machine verification and accuracy.
Keywords: EN ISO 19958, ISO 19958, top piece retention strength, heel top piece test, footwear test methods, heel durability, top‑piece pull‑off test, tensile testing machine.