Influence of Surface Roughness of Tools on the Friction Stir Welding Process

Hartmann, Michael; Böhm, Stefan; Schüddekopf, Sven

doi:2014.32.6.558

J Weld Join > Volume 32(6); 2014 > Article

Research Paper

Journal of Welding and Joining 2014;32(6):558-564.
DOI: https://doi.org/10.5781/JWJ.2014.32.6.22 Published online December 31, 2014.

Influence of Surface Roughness of Tools on the Friction Stir Welding Process

Michael Hartmann^*, Stefan Böhm^*, Sven Schüddekopf^*

Correspondence: Stefan Böhm,
Email: s.boehm@uni-kassel.de

Abstract

Most publications on friction stir welding describe phenomena or results with given process parameters like feed rate, rotation speed, angle and depth of penetration. But without a complete documentation of tool design, the results under the same process parameters are completely different.
For this purpose, the Institute of Cutting and Joining Manufacturing Processes (tff), University of Kassel investigated the influence of tool roughness on the friction stir welding process. Therefore a defined surface finish was produced by turning and die sinking. As basis of comparison the constant parameters were rotation speed, feed rate, tilt angle and a heel plunge depth. Sound butt-welds were produced in aluminium alloy 6082 (AlMgSi1) with 1.5 mm sheet thickness with a turned reference tool with a surface of Ra = 0.575 ?m in position controlled mode. The surfaces are manufactured from a very fine to a very rough structure, classified by the VDI-classes with differences in the arithmetical mean roughness.
It can be demonstrated with the help of temperature measures, that less heat is generated at the surfaces of the shoulder and the pin by the higher roughness due to lower active friction contact surface. This can also be seen in the resulting wormhole defects.

Key Words: Friction stir welding, Tool design, Surface roughness