In the sample enclosed, the lid of the cooling element is inlaid and the joint is both pressure and vacuum sealed using friction stir welding. The two drill holes show the inlet and outlet of the cooling duct. Friction stir welding (FSW) makes it possible to create geometries that are impossible with casting and extrusion methods. As such, FSW opens up new, elegant ways for the construction of components. Pores are eliminated in the welding seam of a cast material and there is no risk of the leakages that arise in traditional processes (MiG, WiG and laser welding as well as soldering, bonding, screwing and seals). Non-standard mixed joints such as aluminium and steel/stainless steel, aluminium and copper, or pure copper joints are also possible.

The metallographic microsection – created as a cross-section to the weld seam – shows precisely how the materials of the join partners are mixed together. With careful polishing followed by etching, the microstructure is revealed under the microscope. These microsections are an essential part of quality assurance in friction stir welding joints. Comprehensive quality assurance in accordance with international standards:

Our comprehensive quality assurance combines the following core elements:

• Standardised definition of requirements based on: Quality and testing requirements from DIN EN ISO 25239-5
• Precise process control using automated parameter regulation with set tolerances for process parameters
• Multistage testing procedure::
  • Visual inspection: to identify external weld defects (pores, underhung seam, welding ridges)
  • Seal test: to quantify the leak rate using pressure difference tests
  • Burst testing: to determine bursting pressure, critical component areas and to analyse break points
• Metallographic examination: to analyse material mixing (weld seam structure), to detect internal weld defects, and to analyse seam position and welding penetration depth
• Advanced technological tests (if required): hardness mapping, tensile strength analysis, strain measurements, X-ray testing

This comprehensive quality assurance enables us to guarantee the maximum precision and reliability of our friction stir welding – for your challenging metalworking projects.

In the section on the left, the weld is cut longitudinally, so the weld runs from right to left. The characteristic squamous mixing of the two alloys is visible as a result of the different etching characteristics after polishing the specimens. The cross-section (right) – which was made at 90° to the weld seam – also shows the mixing of the two alloys. This clearly reveals the defined welding penetration depth and the weld area.

Friction stir welding marks a milestone in welding technology. It revolutionises the joining of light metals by achieving a hitherto unmatched joint quality and at the same time opening up entirely new perspectives in joint design.

Discover the future of friction stir welding – from development to series production – with RRS Schilling GmbH.