How to weld aluminium with a mig welder? | 7 great Steps

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In this article, we will explore the question “How to weld aluminium with a mig welder?

To MIG weld aluminum, you will need to follow some specific procedures and use the right equipment. Aluminum wire is more challenging to feed through the MIG gun than steel wire, so a spool gun is recommended.

However, it is possible to weld aluminum with a regular MIG welder by using a Teflon liner and a push travel angle of 10-15 degrees. Here are 7 great steps to MIG weld aluminum:

1. Clean the aluminum thoroughly to remove any oils, dirt, or oxides that could interfere with the weld.

2. Set up your MIG welder with the appropriate wire, gas, and settings. Use a Teflon liner to feed the aluminum wire through the MIG gun.

3. Use a push travel angle of 10-15 degrees, with the tip and nozzle pointed in the direction of travel.

4. Use a steady, even motion to feed the wire and create a consistent weld bead. Avoid stopping and starting, as this can create a weak spot in the weld.

5. Use a high-frequency start to initiate the arc, as aluminum requires a higher voltage to start than steel.

6. Use a shielding gas of 100% argon to protect the weld from oxidation.

7. After welding, clean the weld with a stainless steel brush to remove any oxides that may have formed during the welding process.

It is also possible to convert a regular MIG welder to weld aluminum by adding a spool gun and using 100% argon gas. However, this may require some modifications to the welder and is not recommended for beginners.

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What type of shielding gas is commonly used for MIG welding aluminum?

The most common shielding gas used for MIG welding aluminum is 100% argon. This gas allows you to get into a spray transfer or pulsed spray transfer mode easily for aluminum due to its low ionization value. 

Up to a sheet thickness of approximately 12.5mm, pure argon is the most popular choice for MIG welding aluminum. However, argon helium blends can also be used, but they should be used with caution and only when necessary.

Some factors to consider when choosing a shielding gas for MIG welding aluminum include:

1. Ionization potential and thermal conductivity: These properties of the shielding gas can affect the welding process and the quality of the weld.

2. Cost: Helium is more expensive than argon, so it’s essential to consider the cost implications when choosing a shielding gas.

3. Heat input: Helium blends can provide deeper penetration and more heat into the part, but this may also result in a higher heat input and the need to adjust the gas flow and arc voltage to maintain a stable arc.

In summary, 100% argon is the most commonly used shielding gas for MIG welding aluminum, but argon-helium blends can also be used in specific situations. It’s essential to consider the factors mentioned above when choosing the right shielding gas for your MIG welding projects.

Is pre-heating necessary for aluminum MIG welding?

Preheating is generally not required for MIG welding aluminum. In fact, preheating aluminum to high temperatures can degrade its mechanical properties significantly. 

However, a little preheat to 250 degrees Fahrenheit maximum can help drive off water vapor or condensation, which minimizes porosity. Preheating can also be helpful when welding two pieces of metal with different thicknesses. 

For example, if you want to join a 3/32-in. piece of 6061-T6 sheet to a 3/8-in. A356 casting, preheating the casting to 200 degrees Fahrenheit makes it easier to weld them together.

In summary, preheating is generally not necessary for MIG welding aluminum, and it can even be detrimental to the mechanical properties of the material. However, a little preheat to drive off water vapor or condensation may be helpful in some cases.

What are the common challenges or issues faced when MIG welding aluminum?

MIG welding aluminum presents some unique challenges that can result in various issues or defects. Some of the most common challenges or issues faced when MIG welding aluminum include:

1. Porosity: Pinholes form in the weld bead face and weld interior in the absence of shielding gas, which can be caused by improper equipment settings, a hole in the gun liner, or wind.

2. Lack of fusion: This occurs when the weld metal does not fuse completely with the base metal, resulting in a weak joint.

3. Burn-through: Aluminum conducts heat about six times faster than steel, has excellent thermal conductivity, and has a low melting point, making it extremely susceptible to warping and burn-through.

4. Wire feeding issues: Aluminum wire has less tensile strength than steel wire, which can pose wire feeding issues and lead to weld defects if not using the correct equipment.

5. Cratering: A common MIG welding defect is when craters form at the end of a weld. If operators do not fill them in, they create a stress point, which can lead to cracking.

6. Erratic wire feeding and arc issues: This can be caused by using the wrong kind of contact tips, with the size matched to the wire diameter being used, or using a contact tip designed for steel wire rather than a tip for aluminum wire.

To avoid these issues, it’s essential to use the right equipment, follow proper procedures, and select the appropriate filler metal and consumables. It’s also crucial to choose the right shielding gas, with 100% argon being the most commonly used gas for MIG welding aluminum.

What are the recommended wire feed settings for welding thin aluminum sheets?

The recommended wire feed settings for welding thin aluminum sheets typically fall within the range of 240 to 290 inches per minute (ipm) with travel speeds between 14 and 19 ipm. 

These settings can serve as a good starting point, but adjustments may be necessary based on the specific welding conditions and equipment being used.It’s important to note that the wire diameter, contact tip size, and type of aluminum welding wire being used can also influence the wire feed settings.

For instance, using a .030″ 5356 Aluminum MIG welding wire with a .035″ contact tip is a common practice. Additionally, a Teflon liner in the MIG gun is recommended when welding aluminum to ensure smooth wire feeding.

In summary, when welding thin aluminum sheets, starting with a wire feed speed in the range of 240 to 290 ipm and making adjustments based on the specific welding conditions and equipment used is recommended. Additionally, using the appropriate wire diameter, contact tip size, and a Teflon liner can contribute to successful welding outcomes.

Can you briefly explain the role of a spool gun when welding aluminum with a MIG welder?

A spool gun is a specialized gun used in MIG welding to feed soft aluminum wire directly from the spool to the weld, bypassing the long cable in a regular MIG gun.

This setup prevents the aluminum wire from binding or getting tangled, which can occur when using a regular MIG gun due to the softness of aluminum wire. The spool gun holds a spool of wire, allowing for a short and straight feed path, which is particularly beneficial when welding aluminum.

When welding aluminum with a MIG welder, a spool gun is often used to address the challenges associated with feeding soft aluminum wire through a long cable. It allows for better control and feeding of the aluminum wire, ultimately leading to improved weld quality and reduced feeding issues. 

Additionally, using a spool gun enables welders to perform MIG welding in the spray transfer mode, which is more suitable for aluminum welding compared to the short-circuit arc used for steel welding.

In summary, a spool gun plays a crucial role in MIG welding aluminum by providing a direct and controlled feed of soft aluminum wire, thereby addressing feeding issues associated with using a regular MIG gun and enabling the use of the appropriate welding mode for aluminum.

In what situations would pulse MIG welding be advantageous for aluminum welding?

Pulse MIG welding offers several advantages for aluminum welding, especially in situations where traditional spray transfer MIG welding may lead to weld defects or other issues. Some of the advantageous situations for pulse MIG welding aluminum include:

1. Weld Defects and Problems: Pulse MIG welding is beneficial for aluminum applications prone to weld defects such as lack of fusion, porosity, burn-through, spatter, or warping. The lower heat input generated by the process can help minimize these issues.

2. Thick and Thin Aluminum: It can be used for welding both thick and thin aluminum. On thicker sections, it helps minimize downtime for repositioning parts and generates a cooler weld puddle, making it usable in all positions. On thinner sections, it minimizes the opportunity for burn-through and reduces the risk of warping by controlling the heat input.

3. Deposition Rates and Productivity: Pulse MIG welding allows for the use of a larger diameter wire, which increases deposition rates and productivity. It also enables faster wire feed and travel speeds, contributing to increased productivity.

4. Bead Profile and Arc Control: Pulse MIG welding provides better control over the weld puddle, allowing for control of the bead profile and improved arc starting and stopping.

In summary, pulse MIG welding is advantageous for aluminum welding in scenarios where traditional MIG welding may lead to weld defects, for welding both thick and thin aluminum, and for achieving higher deposition rates and productivity.

It also provides better control over the weld puddle and bead profile, making it a beneficial process for aluminum welding.

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