Overview
ISO 18785-4:2018 - "Friction stir spot welding - Aluminium - Part 4: Specification and qualification of welding procedures" defines the required content and qualification process for welding procedure specifications used for friction stir spot welding (FSSW) of aluminium and its alloys. The standard sets out how manufacturers should prepare a preliminary welding procedure specification (pWPS), qualify it through testing, and record the approved welding procedure qualification record (WPQR) prior to production welding.
Key Topics and Requirements
This part of the ISO 18785 series focuses on practical and auditable requirements for FSSW welding procedures. Key technical topics include:
- Welding procedure documentation
- Content required in a pWPS (preliminary Welding Procedure Specification) and conversion to a WPQR.
- Required pWPS content (examples specified)
- Manufacturer information, parent material composition, material dimensions
- Welding method, machine specifications, tool identification
- Clamping processes, joint design, joint preparation and cleaning
- Welding technique and post‑weld processing
- Qualification methods
- Qualification based on standardized welding procedure tests (Clause 5) or pre‑production welding tests (Clause 7). The choice depends on how well test pieces represent the production geometry.
- Examination and testing
- Visual testing, destructive testing (including re‑testing rules), and macrosection examination.
- Range of qualification
- Rules for the scope of the qualified procedure: manufacturer-related variables, material-related variables, common variables and other factors that affect transferability of the WPQR.
Applications and Who Uses ISO 18785-4:2018
ISO 18785-4:2018 is intended for organizations and professionals involved in specifying, qualifying and controlling FSSW of aluminium. Typical users include:
- Welding engineers and procedure writers preparing pWPS/WPQR for FSSW
- Manufacturers and production engineers in automotive, aerospace, rail, marine, consumer goods and food processing industries where aluminium FSSW is used
- Quality managers, inspectors and NDT personnel responsible for welding qualification and inspection
- Tooling and machine suppliers who must document machine and tool specifications for procedure qualification
Practical benefits: consistent, auditable welding procedures; reduced production defects; clearer transfer of approved welding parameters across manufacturing sites; and improved conformity with industry best practices for aluminium FSSW.
Related Standards
Relevant linked documents referenced by ISO 18785-4:2018 include:
Implementing ISO 18785-4:2018 helps ensure that friction stir spot welding procedures for aluminium are robust, repeatable and qualified for production use.
Open preview (PDF)Friction stir spot welding — Aluminium — Part 4: Specification and qualification of welding procedures