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What Type of Welding is Used for Aluminum?

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When it comes to working with metals, welding is one of the most important fabrication methods that can be employed.  It’s essential that you match up the right technique with the correct material in order to have the most effective and efficient workflow. This is especially true with aluminum, as certain alloys are much easier to weld than others; knowing which type of alloy you’ll be using will help determine the most appropriate welding method.

Aluminum is well known for being difficult to weld, but with experience, it’s no more demanding than any other metal.  That’s why it’s essential that manufacturers not only spend the time necessary researching and testing materials and methods, but also make sure welders are properly trained.  This will help the entire production process operate more smoothly.

In addition to reviewing the different techniques for welding aluminum, we’ll also be looking at some of the challenges that aluminum presents and offer some possible solutions.

What are the aluminum properties that make it more challenging to weld?

Aluminum is an amazing metal, one that has completely revolutionized nearly every industry since it was first commercialized just over a century ago.  From aerospace and aviation to food and beverage packaging, its light weight, high strength and extreme versatility mean that it is often the most cost effective material available for any given task. This is before we even mention its elevated corrosion resistance.

When it comes to welding, many of the same properties that make it so desirable can often become drawbacks.  For instance, when compared to steel, aluminum has a significantly lower melting point.  When you combine this with aluminum’s increased thermal conductivity, it’s much easier to burn through the metal while welding; particularly when working with aluminum sheet.  Another concern is that aluminum feeder wire tends to be softer than other metals, making it easier to become tangled in the feeder.

Perhaps the most important thing to realize is that welded aluminum is generally weaker than the parent material.  This is not true with other metals such as steel, which have welds just as strong as the original metal.  This is because non-heat treatable aluminum is hardened through a process known as cold working.  Welding a metal that has been cold worked is similar to annealing the metal, which will result in the material being softened to its original state.  Similarly, when working with heat treatable aluminum, the welding process heats the metal to a much greater temperature than the heat treatment, causing the aluminum to lose some of its mechanical properties.  That’s why it’s necessary to perform post-weld heat treatments after the weld has been performed to improve the post-weld strength.

What are the different methods for welding aluminum?

Perhaps the most common form of aluminum welding is known as gas tungsten arc welding.  Another name for this is tungsten inert gas (TIG) welding.  It is characterized by the use of a non-consumable tungsten electrode.  The inert gas, such as argon or helium, protects against oxidation or other atmospheric contamination.  There needs to be a constant welding power supply to produce the required electrical energy, which gets conducted across the arc via a column of plasma and consists of highly ionized gas and metal vapors.

This method has the advantages of being very clean and doesn’t require wire filler material, but it is more complicated than some other possible methods, which means you really need to have an experienced operator.

Another possible option is called gas metal arc welding or metal inert gas (MIG) welding. This method relies on an electric arc between the consumable MIG wire electrode and the work piece.  There is also a shielding gas that is fed through the welding gun in order to block any possible contaminants.  The method was originally developed in the 1940s specifically for welding aluminum and other non-ferrous metals, and it is prized for its faster welding time.  Additionally, it has increased in popularity because of the ease of adapting the process to robotic automation.

Laser beam welding can also be used.  This method joins the separate pieces of metal through the use of a laser.  The laser beam offers a concentrated heat source, which allows for narrow, deep welds and high welding rates.  One advantage of laser beam welding is it offers a high power density, which allows for a smaller heat-affected zone, with higher heating and cooling rates.  It’s important to remember that the depth of penetration is proportional to the amount of power supplied.

What safety precautions should be taken when welding aluminum?

No matter what method of welding you use, it’s imperative that you always follow all recommended safety precautions.  To ensure safety, it’s smart to prepare your equipment and materials beforehand and inspect them regularly to make sure everything is in working order.  Personal protective equipment should be worn at all times, including a welding mask for eye protection, thick gloves, a leather smock to protect from sparks and work boots to protect your toes.

Another thing to remember is that following a weld, the metal needs to adequately cool before handling.  Even if the metal is no longer bright red, it could still be hot enough to burn exposed skin if you grab it too soon after welding.  If you will be welding for long periods of time, you’ll also want to use a respirator to avoid breathing in toxic fumes.

One of the best things you can do to ensure a proper weld is to work with a material supplier to pick out the right material.  At Clinton Aluminum, we strive to be a true partner to our customers, and we’re ready to help you through every step of the procurement process.  Aluminum welding is a tricky operation that can be time-consuming, costly and even dangerous if not done properly.

Contact one of our sales professionals today to learn more about how to pick out just the right welding material.

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