Lightweight structures in automotive engineering is under pressure. In order to extend vehicle range and comply with CO₂ targets, OEMs are increasingly relying on high-strength aluminium alloys and hybrid structures such as aluminium–steel joints. Previous friction stir welding systems have struggled in flexible series production because the high process forces necessitated heavy, rigid counter supports. The “Steppwelder”, developed at the MPA of the University of Stuttgart, is designed to make the process suitable for series production for the first time in a flexible, robot-based set-up without heavy external counter holders.
- 03/10/2026
- Report
- Lightweight trend
- Further processing of castings
Robotic friction stir welding: “Steppwelder” makes lightweight structures suitable for series production
Friction stir welding is regarded as a mature technology. In flexible series production, however, it has often failed due to a practical constraint: high process forces requiring massive counter supports. Researchers at the Materials Testing Institute (MPA) of the University of Stuttgart have now developed a solution. With the “Steppwelder”, the process can be deployed robotically and without external support structures.
Written by Editors EUROGUSS 365
Self-contained force loop and the quilted seam principle
At the core of the development by the team led by project manager Dominik Walz, together with inventors Florian Panzer, Stefan Weihe and Dr.-Ing. Martin Werz, is a robot-guided friction stir welding gun with an integrated, actively movable counter support. This creates a self-contained force loop within the gun frame itself, enabling operation on conventional 6-axis industrial robots without complex external fixtures.
Technically, the system is based on the so-called “quilted seam principle”. Instead of producing one continuous weld seam, short seam segments are created sequentially. These quilted seams can be strung together to form long, material-tight joints, including complex 2D and 3D geometries. According to the development team, a seam of 50 millimetres can currently be produced in 1.5 to 2 seconds, meeting the cycle times required in automotive production.
Validation phase until June 2026
The technology is described as having reached an advanced level of maturity. A complete welding cell for validation trials, including a digital twin, is available. The project is funded with approximately €1.4 million under the German Federal Ministry of Education and Research’s “VIP+” validation programme.
Completion of the validation phase is scheduled for June 2026, after which the technology is expected to be ready for industrial deployment in automotive, aerospace and mechanical engineering applications. Technologie-Lizenz-Büro (TLB) GmbH is supporting the market introduction of the patented innovation.
Benefits for industry and the environment
The process operates without filler metals, generates neither smoke nor spatter and requires low specific energy consumption. At the same time, it enables significant weight reductions in complex geometries such as battery housings or large structural cast components, supporting lightweight multi-material design in series production.
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Editors EUROGUSS 365
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