Overview
EN ISO 18278-2:2016 - Resistance welding - Weldability - Part 2: Evaluation procedures for weldability in spot welding specifies test procedures to determine the acceptable welding current range and to estimate electrode life for resistance spot welding. Adopted by CEN (EN ISO 18278-2:2016) and published as the second edition of ISO 18278-2, this standard is applicable to assemblies of uncoated and coated sheets with individual thicknesses from 0.4 mm to 6.0 mm. It is intended for consistent, repeatable evaluation of spot-welding performance across materials, electrodes and equipment.
Key Topics and Requirements
The standard provides structured procedures, measurement criteria and reporting requirements including:
- Scope and applicability - evaluation of weldability for coated/uncoated sheets 0.4–6.0 mm.
- Welding equipment and electrodes - general requirements for electrode material, shape, dimensions and cooling.
- Measurement of process parameters - methods to measure welding current, electrode force and cooling water flow.
- Preliminary adjustments - electrode alignment and conditioning to establish baseline conditions.
- Determination of welding current range - stepwise test procedures to find the acceptable current window, including criteria for weld diameter and detection of expulsion.
- Estimation of electrode life - procedures and pass/fail criteria to quantify electrode wear and useful life under specified conditions.
- Measurement of results and destructive tests - guidance on weld diameter measurement and detection of expulsion, with references to standardized destructive tests.
- Reporting - required elements of test reports for both current-range and electrode-life evaluations.
The document also includes informative annexes on electrode alignment, specific conditions for steel sheet qualification, specimen types, and example test reports.
Practical Applications and Users
EN ISO 18278-2:2016 is intended for professionals and organizations concerned with resistance spot welding quality and process optimization:
- Welding engineers and process engineers validating weld parameters and setting production current ranges.
- Quality managers and test laboratories performing standardized weldability assessments and supplier qualification.
- Material and electrode manufacturers assessing compatibility, electrode wear and cooling needs.
- Automotive, appliance and metal manufacturing industries that require reliable spot weld performance for coated and uncoated sheet-metal assemblies.
Using the standard helps reduce process variability, optimize electrode maintenance schedules, and substantiate welding procedure specifications.
Related Standards
Key normative references and related documents cited by EN ISO 18278-2:2016 include:
These related standards should be consulted for equipment requirements, test methods and terminology when implementing EN ISO 18278-2:2016.
