How to MIG Weld Aluminum in 2020 | ultimate guide

If you find difficulty while MIG welding aluminum or want to know how to MIG weld aluminum, you are in the right place. In this article, we will discuss the easiest way to MIG weld aluminum.

Though MIG welding is the easiest process of welding, perfect for the beginners, you may find difficulty while MIG welding aluminum. Before you start welding aluminum with the MIG (GMAW) process, you should keep practicing MIG welding mild steel.

You may think “MIG welding aluminum” and “MIG welding mild steel” are quite similar processes. But unfortunately, there are no similarities between the two processes except the gun angle and gas flow rate. 

MIG welding aluminum is more challenging because of the property of the aluminum, such as

  • Distortion property
  • Pure aluminum is soft
  • Addition of alloy(s) makes it harder
  • Very sensitive to heat input.

Special consideration for MIG welding aluminum

Material thickness

Should be between 14-18 gauge. Consider using an AC TIG welding equipment or specialized pulsed MIG while MIG welding thinner material than 14 gauge.

Clean the base metal before starting MIG weld aluminum

Before starting your welding process make sure you have cleaned the metal thoroughly including any lubricants. 

After cleaning the metal thoroughly you will have to remove the oxide from the metal. It is crucial because the melting temperature of oxide is two times greater than the melting temperature of aluminum itself.

Consider using an aluminum wire brush to clean the metal because using steel brush will contaminate the metal you will be welding.

Shielding gas

Being non-ferrous metal aluminum requires 100% argon shielding gas. Flow rate should be between 20-30 CFH (cubic feet per hour).

If your material is thicker than ½ inch or more,you will need better penetration; therefore, addition of 25% to 75% helium is recommended. 

AC or DC

While welding aluminum DC (direct current) set up is important.

Modes

Three modes are available for MIG welding aluminum such as

  • Short circuit mode
  • Spray transfer mode
  • Pulsed  MIG modes

While welding aluminum, short circuit mode should be avoided as it causes the weld to be prone to breaking or cracking. Obtaining a better appearance and strength of the weld is quite impossible by short circuit mode.

In the case of spray transfer mode, not only the appearance is nice but also the arc is smooth and stable because it transfers the molten droplets from the electrode to the puddle. The only thing to give attention in spray transfer mode while welding thin (⅛ inch or less) material is the travel speed as it involves high heat. So, you will need a higher travel speed and a thinner (.030 inch) filler wire to prevent burn-through by keeping the heat input down.

In the case of pulsed MIG mode, the wire will be decreased to a lower amperage followed by transferring across the arc; therefore, this mode is suitable for out-of-position welds while spray transfer mode is not suitable for out-of-position welds. Thinner gauge material (below ⅛ inch) can be welded with a larger diameter wire (up to 3/64 inch) in this mode as it gives better control for the heat input. Thus, it prevents burn-through.

Some considerations to prevent burn-through

  1. Reducing gaps
  2. Spread out the heat by moving around the part
  3. Make smaller welds
  4. Enhance the travel speed

Spool gun or push pull system?

Both spool gun or push-pull system are used to fed aluminum wire. With spool gun you can solve the problem of birdnesting as the wire only feeds for a few inches.it also improves the feeding of soft wires.

In the push-pull system, the wire is pulled through the liner by a motor fitted in tn the gun that acts as an assist motor.

Advantages of push-pull system

  • Ergonomic
  • User-friendly
  • Suitable when welding in distance from the power source

How to MIG weld Aluminum with Filler metal

ER4043 and ER5356 are the most available filler wires in the market and they are appropriate alloys for about 85 percent of aluminum application.

Using ER4043 as filler metal will make the weld pool quite fluid as it contains 5 percent silicon; therefore, it requires a higher voltage while welding than other aluminum alloys. If your applications are subjected to long term elevated temperature, ER4043 is going to be the right choice for you

Advantages of ER4043

  • Minimize opportunities for termination and shrinkage cracking
  • Reduce distortion on aluminum
  • Achieves brighter welds without smut
  • If the aluminum you are welding is 5XXX series or 6XXX series (containing less than 2.5 percent magnesium ) you are allowed to use either ER4043 or ER5356.

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