Welding aluminum generally requires specific techniques and equipment different from welding steel, primarily due to aluminum's properties like softness, oxidation tendency, and thermal conductivity. The two most common welding methods for aluminum are TIG (Tungsten Inert Gas) welding and MIG (Metal Inert Gas) welding.
How to Weld Aluminum
- Choose the right welding process:
- TIG Welding: Uses alternating current (AC) to clean the aluminum oxide layer and heat the metal, producing a clean, precise weld. It requires a pure tungsten electrode and 100% argon shield gas.
- MIG Welding: Uses a continuously fed wire and inert gas shielding, typically argon. A spool gun or push-pull system is often required for feeding aluminum wire due to its softness.
- Preparation:
- Clean the aluminum thoroughly using a stainless steel wire brush to remove the oxide layer and contaminants.
- Preheat thicker sections of aluminum to reduce warping and cracking.
- Clamp the workpieces securely, sometimes using a heat sink to absorb excess heat.
- Welding Technique:
- For TIG, feed the filler rod manually into the weld pool while maintaining proper arc length and travel speed.
- For MIG, use a pushing technique at a slight angle, with multiple passes for thicker materials.
- Use appropriate filler rods or wires matched to the aluminum alloy.
- Use alternating current in TIG to break up oxide and ensure good penetration.
- Post-Weld:
- Inspect the weld for porosity, cracks, or other defects.
- Clean the weld area of any residue.
Alternative Methods
- Aluminum can also be brazed using a propane torch and aluminum brazing rods if welding equipment is not available, but this creates a mechanical bond rather than a true weld.
Tips and Considerations
- Avoid flux-cored arc welding as it can cause porosity in aluminum.
- Use proper protective equipment.
- Patience and practice are essential since aluminum welding requires control over heat input and contamination.
This overview covers the essentials for welding aluminum successfully using typical methods (TIG and MIG) and includes preparation and technique details, emphasizing the need for clean surfaces and control of heat and shielding gas.
