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How To Weld Aluminum

How To Weld Aluminum
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Last Updated: 09 July 2020

Welding aluminum is not an easy task; it presents a lot of unique challenges as compared to welding steel or other common metals, especially in terms of crack sensitivity and chemistry. In most cases, welding cast aluminum needs special procedures. You need to factor in some considerations like proper welding techniques, thorough cleaning of the base material, storages, etc. You might also need a welder for aluminum.

A sound weld is all about proper technique, the reduction of hydrocarbons, and chemistry. When compared with steel, aluminum showcases many different characteristics. For instance, what temp does aluminum melt? The melting point is 1,221°F, which is much lower than that of steel – 2,500°F.

Additionally, it also has a layer of oxide that melts at 3,700°F; this oxide layer is much more resistant than the metal itself and helps the material resist abrasion and corrosion. However, this same layer acts as an insulator and prevents easy welding. But how will a welder for aluminum help?

The metal’s strength increases as the service temperature decreases; steel, on the other hand, becomes more brittle as the service temperature decreases. This is the reason why the metal is so commonly used in cold-temperature appliances and devices like liquid natural gas transportation and cryogenics. Similarly, there are a lot more differences if you want to learn how to weld aluminum.

While steel’s primary alloy is iron, aluminum consists of a mixture of a lot of other elements. Pure aluminum with no alloying materials is known as wrought alloys, like the 1xxx series. Similarly, the other principal alloying elements in other types include:

  • 2xxx: Copper alloy
  • 3xxx: Manganese alloy
  • 4xxx: Silicon alloy
  • 5xxx: Magnesium alloy
  • 6xxx: Silicon and magnesium alloys
  • 7xxx: Zinc alloy
  • 8xxx: Others

How To Clean Aluminum Before Welding?

How To Clean Aluminum Before Welding

Before you learn how to weld aluminum at home, you need to learn how to clean it first. Pre-weld cleaning consists of two primary jobs – removal of the grease and oil and then oxide removal. Before you try anything else, you need to remove any water vapor, grease, or oil from the surface. This is valid even if you use a welder for aluminum or not.

Most people tend to think that using a wire brush is the best way to do this; on the contrary, the wire brush will only create small scratches and spread them around, making them impossible to remove later.

Before you start using the welder for aluminum, you first need to remove the oil, then the grease, and the other contaminants in the last. There are two classes of liquids that are effective degreasers – mild alkaline solutions like strong soaps and organic solvents like acetone.

In contrast to popular aluminum welding tips, alcohol is not a good degreaser and should not be used for cleaning. Additionally, most shops have stopped using several organic solvents since they have been prohibited for environmental reasons. This does not leave you with a lot of options, and the choice often varies from one facility to the other. Toluene, lacquer thinner, methyl ethyl ketone, and acetone all make good solvents.

After you choose the solvent of your choice, you need to wipe the part that needs to be welded with a lint-free and clean rag, dipped in the solvent. You will notice that the solvent will evaporate almost immediately. You need to ensure that the solvent is evaporated completely before you weld the parts together. You should also never pour solvent directly on the welded joint; this could release poisonous gases. It’s also valid if you use a professional welder for aluminum.

Once you are done with the cleaning aluminum for welding, you need to remove the oxide on the surface. You can make use of a stainless steel wire brush for this; however, it should be used only for this metal and be cleaned. Also, the bristles need to be fine and soft. A heavy brush will burnish the oxide, rather than remove it.

You can also make use of different chemicals to remove the oxide. Strong alkaline chemicals are good options. Alternatively, most welding suppliers also sell oxide-removing chemicals in squeeze or spray bottles for local applications. Once the oxides are removed, you need to rinse the part in hot water and dry them completely. Let’s now see how to find the best welder for aluminum.

TIG Welding Aluminum

TIG Welding Aluminum

In this section, we will cover MIG vs TIG welding aluminum. In the TIG welding, the requirements include a clean surface to remove any buildup of oxide, a tungsten non-consumable electrode, and shielding gas (usually argon). Since the oxide has a higher melting point, it needs to be removed before the welding process.

The welder for aluminum needs to be built for TIG welding and should be fitted with the required accessories. Foot control is required since the heat gradually builds up as the welding progresses. Additionally, less heat is needed from the electrode as the welding comes to an end.

If you are looking for the best results, you can choose alternating current, or AC, at a high frequency. Thanks to the high frequency, the tungsten electrode of the welder for aluminum does not touch the metal, thereby reducing the risk of contamination.

In the hands of a skilled TIG welder, a TIG weld will look and seal better than MIG welding. Additionally, the efficiency is high, and there is no spatter and slag. Fusion welding becomes a possibility and is an excellent choice for fragile materials. All positions of welding are possible, and the weld quality is very high.

MIG Welding Aluminum

MIG Welding Aluminum

MIG welding is possible if you have the right equipment that can connect to reverse polarity settings and direct current (DC). While you can weld in almost any position, you should leave the more challenging ones for an experienced aluminum welder. You will also find a lot of MIG welding tips on the net.

Before you start with the MIG welding process, you need to have a tank of shielding gas; argon gas will work the best as it results in a steady and smooth arc. Alternatively, you can also make use of an argon-helium mix. Also, a filler wire might jam the system easily. Hence you can use a spool gun or a push-pull wire feed system to avoid this problem.

You first need to strike a clean electrode for welding at around an inch from the start of the process. Then, you need to quickly move it over to the point from where you want to start your procedure with the welder for aluminum.

You can make use of the string bead technique to move along the weld. You then need to turn swiftly over to the point where you started the process. You can use the string bead technique, but you should be careful so that you do not change the angle of the electrode as you work. While you are nearing the end of the weld, you can increase the speed with your welder for aluminum.

MIG welding is much faster than TIG welding. Since there is no flux, you will not see any slag in the metal. The best MIG welder is also quite versatile and can be used with a wide range of alloys and metals like nickel, magnesium, copper, etc. The process can also be worked in many different ways, including semi- and fully-automatic. This type of welding is mostly used in industries that work with a wide range of structures, parts, and materials.

Stick Welding Aluminum

Stick Welding Aluminum

Can you stick weld aluminum? Yes, you can! In the past, TIG welding was most commonly used for welding aluminum. Later, several newer methods started gaining popularity because they produced high-quality welds with less training. One of these methods is stick welding.

Today, stick welding is one of the most used methods. This is an excellent choice for repairing tanks and pipes, and a welder for aluminum works excellent in this case. The process joins metal pieces with the help of an electric arc, thereby creating a lot of heat and melting the metal parts.

If the material is melted with a coated electrode of the best stick welder, it will get mixed with a filler; this joins the two parts into a single unit. Mostly, the electrode used is coated. This welding process is quite fast and does not allow the metal to touch the arc too much.

The electrode is heavily dipped in flux and then used along with the DC reverse polarity. This coating of flux also acts as a gaseous shield for the molten aluminum and the arc, apart from removing the oxide on the metal.

Additionally, some of the flux might also evaporate to form shielding gases in the arc, thereby stabilizing and shielding it from the surrounding environment. The polarity and current settings on the electrode will eventually depend on the electrode’s type.

Push or Pull Stick Welding

There are primarily two types of stick welding methods – the pull and push welding methods. The pull method is the one that is more common among the two; most professionals around the world use it. This is usually because this method works for welding jobs that have slag. When you use the push method on the slag, it often tends to run over it and gets trapped in your puddle, which creates a lot of defects. As the simplest solution, most welders prefer working the pulling-style with any welder for aluminum.

Even in jobs that do not create slags, most welders prefer the pull stick welding method. This is because the pulling allows you to watch where you are coming from, instead of where you are heading (in the case of push stick welding). Pulling allows you to see your bead as soon as it is created.

While pulling stick welds might create deeper penetrations, pushing will often leave a flatter weld that covers more surface area. In some cases, the weld created here is much stronger than the pull stick technique.

While the pull stick welding method allows you to see the bead as soon as it is created, it also limits your view on where you are heading. If you are using a welder for aluminum on an irregular piece of material, you will often stop to see which direction you are heading. The push technique does not allow you to lose focus on the job.

How To Bond Aluminum Without Welding

How To Bond Aluminum Without Welding

While there are several methods of bonding metal without welding, here is the most common one if you want to know how to weld aluminum without a welder:

You first need to purchase a propane torch and some brazing rods. Proceed to cut the metal; it is soft enough to be cut with ordinary woodworking saw blades.

Next, you will have to chamfer the edges to that a channel is created for the brazing materials. Ensure that the metal is cleaned with a wire brush before the brazing.

With the propane torch, start heating it. You need to use your welder for aluminum and hit temperature where the metal is hot enough to melt without melting the brazing aluminum welding rods.

Start rubbing the rod along the channel until it is filled in completely; finish off with additional heat.

Can You Weld Aluminum To Steel?

Can you weld aluminum to steel? Yes, but it is difficult. You can do it to almost any other type of metals via mechanical fastening or adhesive bonding. However, special aluminum welding techniques are required if you want to use your welder for aluminum with steel.

When metals like titanium, magnesium, copper, and steel are arc-welded directly to aluminum, it forms microscopic intermetallic compounds. To avoid this, you need to isolate the other metal from the aluminum while the welding process. Two of the most popular methods include:

Bimetallic Transition Inserts

Here, you need to create a bimetallic transition insert, which can be described as sections of material that are comprised of one part steel and one part aluminum, already bonded into one.

Coat The Steel Before Welding

Another method that you can use is known as dip coating, or hot dip aluminizing. This means that before the entire welding process, the steel is coated in aluminum first.

Aluminum Welding Safety

You will face a lot of aluminum welding problems. Here are some safety measures that you need to take:

Aluminum Welding Safety
  • The appearance of aluminum does not change when heated. Hence, it makes it difficult to distinguish between the hot and cold ones. Therefore, you should always wear the best work gloves to prevent accidental burning.
  • Using a welder for aluminum can cause electrical shock. Unlike steel, the welding must remain active for the entire duration, thereby increases the chances of electrical shock. The best welder for aluminum needs to be well-insulated, and proper grounding is required to protect you in these cases.
  • It is highly reflective. Due to this, the metal poses more risk of light-related accidents. Hence, long-sleeved clothing like aluminum welding helmet and light-blocking curtains will help minimize your exposure.

The above are some of the ways that you can weld aluminum. Also, you need to take certain precautions while doing so. For more such guides, stick to homemakerguide to find the best welder for aluminum.

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