Welding of Aluminium Castings in Automotive Manufacturing

In pursuing lighter, stronger, and more sustainable vehicles, the automotive industry has increasingly turned to aluminium high-pressure die casting (HPDC) parts. These components offer significant benefits but present unique challenges, particularly when welding is required. This article delves into the intricacies of welding HPDC aluminium parts, with a specific focus on joining them to sheet metal in body-in-white (BIW) production, and highlights findings from recent research by Oscar Samuelsson and Isak Tillberg from the Chalmers University of Technology.

Challenges in Welding HPDC Aluminum

Welding HPDC aluminium parts involves several challenges that stem from the nature of the material and the casting process:

• Porosity: Gas entrapment during the die-casting process can create pores within the aluminium, leading to weak points in welded joints.
  
  
• Thermal Conductivity: Aluminium’s high thermal conductivity requires careful control of heat input to avoid rapid dissipation, which can result in insufficient fusion.
  
  
• Distortion: The high thermal expansion coefficient of aluminium makes it prone to distortion during welding.
  
  
• Alloy-Specific Issues: Different aluminium alloys exhibit varying degrees of weldability, with some being more prone to hot cracking and other welding defects.

Mechanical Testing of Welded Joints

The subframe is a critical component in automotive structures, where cost, weight, and sustainability are paramount. Oscar Samuelsson and Isak Tillberg’s bachelor thesis focused on the feasibility of using a light and cost-effective aluminium subframe by joining HPDC components with extruded aluminium beams.

The study utilized aluminium alloy ENAB 44300 for HPDC parts, produced with vacuum assistance, and Rheocasted plates in aluminium alloy ENAB 42000 supplied by Comptech. Extruded aluminium flat bars made from alloy EN-AW 6063-T6, with 3 mm and 4 mm thicknesses, were also used.

Results from Testing

The study concluded that Rheocasting significantly enhances the weldability of HPDC aluminium, providing a weld quality comparable to that of sheet metal welding. Rheocasting helps reduce porosity and improve bonding strength, making it a viable technique for automotive applications.

Conclusion

The integration of HPDC aluminium parts in BIW production represents a significant advancement in automotive manufacturing. Oscar Samuelsson and Isak Tillberg’s research provides valuable insights into improving the weldability of Rheocasting parts, paving the way for more efficient and robust aluminium structures in vehicles.

As the automotive industry innovates, mastering these advanced welding techniques will be crucial. By focusing on precise process control and continuous improvement, manufacturers can produce lighter, more efficient, safer, and more sustainable vehicles.

If you want to weld aluminium castings that require high leakage or mechanical properties, look into Rheocasting and schedule a Free Consultation Call to get support on your casting.