Overview
ISO 25239-3:2020 - Friction stir welding (FSW) - Aluminium - Part 3: Qualification of welding operators specifies requirements for qualifying welding operators who perform friction stir welding of aluminium and its alloys. It defines acceptable qualification methods, test-piece requirements, essential variables and ranges of qualification, certification validity, and the documented knowledge expected of operators. This part does not cover friction stir spot welding (see ISO 18785 series) or the “operators” definition in ISO 25239-1.
Key Topics and Requirements
- Qualification methods: Operators can be qualified by a standard welding test, a welding procedure test (per ISO 25239-4), pre‑production welding test, or production sample welding test.
- Test welds: Test welds must generally be made in accordance with a Welding Procedure Specification (WPS) and witnessed by an examiner. Minimum weld length for qualification is 500 mm (or equivalent accumulated length from up to three short production items). Test specimens include bend tests and macroscopic examination. Note: NDT is no longer accepted as an alternative to bend testing for operator qualification.
- Essential variables and ranges: Qualification is defined by a set of essential variables. Key variable categories include:
- FSW method (robotic, single-/multi‑spindle, bobbin tool, adjustable probe, etc.) - qualification is method-specific.
- Welding equipment - changes in machine type, control system, or joint sensor arrangements can require re‑qualification.
- Parent materials - a successful test on any aluminium alloy, thickness, or form qualifies the operator across all aluminium alloys, thicknesses and forms.
- Weld joint geometry - qualification on any joint geometry qualifies for all joint geometries.
- Quality acceptance levels - qualification at one acceptance level in accordance with ISO 25239-5 covers all acceptance levels.
- Knowledge assessment: Annex A and Annex B set out required knowledge of the welding unit, its operation and FSW technology; Annex C provides an example qualification certificate.
- Validity: Operator qualification period has been extended to three years with possible prolongation for an additional three years.
Applications and Typical Users
ISO 25239-3:2020 is used by:
- Welding operators and their employers for formal qualification and competence records.
- Certification and examining bodies responsible for witnessing tests and issuing qualification certificates.
- Quality managers and engineers in industries using FSW on aluminium: aerospace, rail and rolling stock, marine, automotive, consumer products, food processing equipment and general manufacturing.
- Procedure writers and trainers who develop WPS and operator training programs.
Related Standards
- ISO 25239-1: Vocabulary for FSW (aluminium)
- ISO 25239-4: Specification and qualification of welding procedures
- ISO 25239-5: Quality and inspection requirements (acceptance levels)
- ISO 18785 series: Friction stir spot welding
Keywords: ISO 25239-3:2020, friction stir welding, FSW qualification, aluminium welding operator, welding procedure specification (WPS), welding operator certificate.