FRICTION STIR WELDING OF ALUMINIUM ROOF PANELS FOR METRO VEHICLES

Abstract

This paper presents the development and industrial implementation of Friction Stir Welding (FSW) for aluminium roof panel assemblies of metro vehicles within the Stadler SBB project. The base material is EN AW 6005A T6 extruded aluminium alloy (group 23.1, EN 15608), with a wall thickness of 3.5 mm and panel dimensions of 2,214 × 2,348 mm. FSW (ISO 4063, process No. 43) was selected for its advantages over fusion welding: reduced heat input, no filler material or shielding gas, minimal distortion, and superior surface finish. Welding was performed on a CNC milling machine at 170 cm/min using a tool with a 15 mm concave shoulder and 6 mm threaded probe. Process qualification per ISO 25239-4 included tensile, bend, and macrographic testing, with all results meeting quality level C (ISO 25239-5). The symmetrical welding sequence covered 12 joints per assembly (27.7 m total), with a maximum pre-weld gap of 0.3 mm, under a three-phase quality control plan. The results confirm FSW as a reliable, efficient, and environmentally sound solution for serial production of aluminium railway components.