Aluminium MIG Welding: Wire, Gas & Common Problems

The best aluminium MIG wire depends on the aluminium alloy being welded. ER4043 is the most common choice for general fabrication because it offers excellent weldability, reduced crack sensitivity and a smooth weld appearance. ER5356 is preferred where higher strength, improved corrosion resistance or anodising is required.

Selecting the correct filler wire ensures strong welds and helps prevent cracking or poor mechanical performance. Always use pure Argon shielding gas and ensure the aluminium is clean before welding.

ER4043 and ER5356 are the two most common aluminium filler wires.

• ER4043 provides excellent fluidity and crack resistance, making it ideal for general fabrication and cast aluminium.
• ER5356 offers higher tensile strength and better corrosion resistance, making it suitable for marine, transport and structural applications.

The correct choice depends on the parent material, the service environment and any post-weld finishing requirements such as anodising.

Pure Argon is the most common shielding gas for aluminium MIG welding because it provides a stable arc, good cleaning action and excellent weld appearance. Helium or Argon/Helium mixtures may be used for thicker sections where increased heat input is required.

Using the correct shielding gas helps improve penetration, reduce porosity and produce clean, high-quality aluminium welds. More detail is in our MIG shielding gases guide.

A spool gun is a MIG welding torch that carries a small spool of aluminium wire directly on the torch. This reduces feeding problems caused by aluminium’s softness and helps produce smoother, more consistent welds.

Spool guns are commonly used for light to medium aluminium fabrication and are often simpler and more cost-effective than push-pull systems for occasional aluminium welding.

Common aluminium MIG welding problems include porosity, poor wire feeding, lack of fusion and contamination.

Aluminium quickly forms an oxide layer that must be removed before welding, while moisture and dirt can introduce hydrogen, leading to porosity. Using clean material, the correct filler wire, pure Argon shielding gas and appropriate machine settings will significantly improve weld quality. For more on these defects, see our MIG defects and troubleshooting guide.

Aluminium is less forgiving than steel, so the right wire, gas and feeding setup make all the difference. Weldability SIF supplies ER4043 and ER5356 aluminium MIG wire — contact our technical team for help choosing filler and consumables for your alloy and application.