Overview
EN 15870:2009 (CEN) defines a standardized method for determining the tensile bond strength of butt joints. Based on ISO 6922:1987 (modified), the method is applicable to all adhesive types and is primarily intended for ambient-condition testing but can be applied across a wide range of temperatures and environmental conditions. The standard requires rigid adherends that meet dimensional tolerances and can withstand test forces.
Key Topics
- Principle: A butt joint formed from two bar or rod adherends, bonded on faces normal to the length, is loaded in tension along its long axis until rupture. The reported result is the force observed at rupture.
- Apparatus: A Class 1 testing machine complying with EN ISO 7500-1 is required. The machine must measure force accurately (recorded force within 1% of true force) and allow steady, controlled increase of load. Self-aligning grips and a simple jig for alignment during bonding are specified.
- Test specimens: Adherends should be rigid and, for comparative testing, identical materials. Typical cross-sections permitted include circular or square (10, 15, 25 or 50 mm) with tolerances of ±0.1 mm; length rules are defined in the standard. Surfaces must be plane and normal to the long axis and prepared per adhesive manufacturer or EN 13887.
- Bonding and conditioning: Use manufacturer-recommended bonding procedures or those that produce an optimum bond. Condition specimens under standard atmosphere (recommended 23 ± 2 °C and 50 ± 5 % RH per EN ISO 291) unless otherwise specified.
- Procedure and reporting: Apply tensile loading at a constant jaw separation rate approximating 10 mm/min so that rupture occurs in (60 ± 20) s. Record the maximum force at rupture and the failure mode (per EN ISO 10365). Report the mean of five valid results, specimen details, bonding conditions, adhesive identification, adhesive layer thickness, and failure types.
Applications
- Quality control and batch verification of adhesives
- Comparative R&D testing of adhesive formulations
- Material qualification for bonded assemblies in design and production
- Environmental conditioning and performance assessment across temperatures and humidity
Related Standards
- EN ISO 7500-1 - Verification of static uniaxial testing machines
- EN ISO 291 - Standard atmospheres for conditioning and testing
- EN ISO 10365 - Designation of main failure patterns
- EN 13887 - Surface preparation guidelines for metals and plastics
- ISO 5893, ISO 3534, EN ISO 472 (referenced for related test and statistical guidance)
This standard provides a practical, reproducible method for measuring adhesive bond strength of butt joints, facilitating consistent reporting for QC, certification and laboratory comparison.