Aluminum Extrusion Processes and Weld Seam Quality

Aluminium extrusion encompasses a variety of techniques in which a heated billet is forced through a shaped die to produce profiles with uniform cross-sections. Key process variants include direct and indirect extrusion, porthole-die extrusion for hollow sections, and billet-on-billet or multi-container extrusion for extended runs. During extrusion, separate metal streams converge and bond under high pressure, giving rise to weld seams that determine mechanical integrity. The quality of these welds depends on parameters such as billet temperature, ram speed, die geometry and internal flow balance. Poor weld formation can manifest as incomplete bonding, voids or weakened grain structures, prompting the removal of scrap length and reducing yield. Advances in numerical simulation, in-die monitoring and novel tooling designs have sought to predict and optimise metal flow, welding pressure and thermal conditions. The interplay between die bridge design, welding chamber configuration and extrusion force governs the uniformity of weld seams, which in turn affects tensile strength, fatigue resistance and dimensional accuracy of the final product. Given aluminium’s widespread use in automotive, aerospace and construction sectors, enhancing weld seam quality through refined process control and bespoke die solutions remains of global significance for energy efficiency, material utilisation and structural performance.

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Aluminum Extrusion Processes and Weld Seam Quality publication trend

The graph below shows the total number of articles in aluminum extrusion processes and weld seam quality across all publications each year (not limited to Nature Index journals).

Technical terms

Extrusion: A process in which a heated metal billet is forced through a die to form a continuous profile.

Porthole die: A die featuring internal bridges that split metal flow into channels, then recombine streams through welding chambers to create hollow shapes.

Charge weld: The transverse bond formed between the trailing end of one billet and the leading end of the next in billet-on-billet extrusion.

Solid-state welding: The pressure-driven bonding of metal streams without melting, occurring within the die under high stress.

Dead metal zone: A region near die walls or bridges where material flow stagnates, affecting local pressure and weld quality.

References

1. Analysis of solid-state welding in extruding wide aluminium hollow profiles using a new three-container extrusion system. Journal of Manufacturing Processes (2023).
2. Charge weld evolution in hollow aluminum extrusion: Experiments and modeling. CIRP Journal of Manufacturing Science and Technology (2024).
3. Investigation of die designs on welding quality and billet material utilisation for multi-container extrusion of wide stiffened aluminium panels. The International Journal of Advanced Manufacturing Technology (2023).