Overview
SIST EN ISO 18895:2018, titled Footwear - Test methods for shanks - Fatigue resistance (ISO 18895:2006), is an internationally recognized European standard developed by CEN and adopted from ISO. This standard provides a precise and reliable test method to assess the fatigue resistance of steel shanks with a minimum length of 100 mm. These steel shanks are critical components used for reinforcing the waist region of women's footwear, as well as certain men's and children's shoes.
Fatigue resistance testing, as outlined in this standard, evaluates how well a shank withstands repeated bending loads over its service life, ensuring durability and structural integrity in footwear design.
Key Topics
- Scope of Application: The standard applies specifically to steel shanks used in footwear reinforcement, focusing on fatigue resistance under cyclic loading conditions.
- Test Apparatus: Equipment includes a test machine with:
- Fixed lower jaw with hardened steel face plates to clamp the shank.
- Adjustable upper jaw applying a specified force (49 N ± 2 N) in harmonic cycles.
- Cycle counter for monitoring the number of load repetitions until failure.
- Torque control devices to ensure consistent clamping force (4,900 N·mm ± 50 N·mm).
- Sampling and Conditioning: At least four complete shank specimens per type are conditioned for 48 hours in standardized atmospheres (per EN 12222) before testing to ensure reproducible results under controlled humidity and temperature.
- Test Procedure: The shank is clamped as it would be in a shoe and bent repeatedly by the upper jaw in a harmonic motion at four cycles per second until breakage.
- Result Expression: Fatigue life is recorded as the number of cycles to failure, with results averaged across specimens.
- Test Report Requirements: Documentation must include test results, reference to the method, sample descriptions, number of specimens tested, deviations from the standard, and testing date.
Applications
- Footwear Manufacturing Quality Control: Enables shoe manufacturers to verify the durability of steel shanks in their products, ensuring reliability and performance in use.
- Research and Development: Assists designers and material scientists in evaluating new shank materials or constructions for improved fatigue resistance.
- Compliance Testing: Supports regulatory and standard compliance testing for footwear safety and longevity standards.
- Multi-Segment Use: Primarily applies to women's shoe shanks but is also relevant to selected men's and children's footwear designs requiring reinforced waist regions.
Related Standards
- EN 12222 / ISO 18454: Specifies standard atmospheres for conditioning and testing footwear components, crucial for preparing samples under consistent environmental conditions.
- EN ISO 12958 (Superseded): This document replaces the previous EN 12958:2000, providing updated test procedures aligning with ISO methodology.
- ISO/TC 216: The ISO technical committee responsible for standards development in footwear, overseeing ISO 18895 and related testing methods.
SIST EN ISO 18895:2018 is a fundamental standard that guarantees the mechanical resilience of footwear shanks, promoting high-quality manufacturing and consumer safety. Its fatigue resistance test method is essential for professionals involved in footwear material testing, quality assurance, and product development.