Overview
EN ISO 18785-1:2021 (ISO 18785-1:2018) is the CEN-adopted vocabulary standard for friction stir spot welding (FSSW) of aluminium and aluminium alloys. Its scope is strictly definitional: it establishes consistent terms and clear definitions for the FSSW process, tool components, process parameters and recognised FSSW variants (basic, refill, stitch, swept, swing). The document supports clear communication across design, manufacturing, testing and procurement for aluminium FSSW applications.
Key topics
The standard defines core FSSW terminology and related concepts, including:
- Fundamental process terms: friction stir spot welding (FSSW), probe, shoulder, exit hole, faying surface, weld setter, welding operator.
- Process parameters: rotation speed, rotation direction, plunge speed, plunge depth, dwell time, force control and position control.
- FSSW variants and tool concepts:
- Basic FSSW - plunge and retraction without traverse.
- Refill FSSW - basic FSSW plus refill action to eliminate the exit hole; includes terms such as adjustable shoulder, clamping ring and clamping ring force.
- Stitch FSSW - short linear or curvilinear tool translation (length of travel, weld width).
- Swept and swing FSSW - tool translation around a circumscribed path (swept) or other motion variants (swing).
- Normative references: aligns with ISO 25239-1 (FSW vocabulary), ISO/TR 25901-1 (welding vocabulary), and ISO 14732 (welding personnel qualification).
Applications and users
This vocabulary standard is practical for professionals and organisations that design, specify, qualify or perform FSSW of aluminium:
- Welding engineers and process developers - to write unambiguous welding procedures and work instructions.
- Quality and inspection teams - to create consistent acceptance criteria and reports.
- OEMs and suppliers (automotive, aerospace, rail, marine, consumer goods, food processing) - to ensure contract and procurement clarity.
- Standards committees and training providers - to standardise terminology in certification, operator training and documentation.
- Equipment manufacturers - to label controls and parameters consistently (rotation speed, plunge mode, clamp force).
Practical value
Using EN ISO 18785-1 reduces misunderstandings in specifications, supports reproducible weld procedures, and helps link process parameters to inspection and qualification regimes. Because “aluminium” in this standard covers aluminium and its alloys, it is directly applicable to the common industrial materials used in FSSW applications.
Related standards
- ISO 25239-1 - Friction stir welding - Aluminium - Part 1: Vocabulary
- ISO/TR 25901-1 - Welding and Allied Processes - Vocabulary - Part 1
- ISO 14732 - Welding personnel qualification (mechanised/automatic welding)
- Other parts of the ISO 18785 series (see ISO catalogue)
Keywords: friction stir spot welding, FSSW, EN ISO 18785-1, ISO 18785-1, aluminium, welding vocabulary, welding standards.