How to Weld Aluminum

Welding aluminum is a unique process that’s different than welding steel. While you can weld aluminum to steel for some jobs, the main difference lies in the fact that aluminum requires a heat point of 1,221 degrees instead of 2,500 degrees for steel.

Welding aluminum requires a thorough understanding of the tungsten inert gas (TIG) welding process and also requires a TIG torch. TIG welding is an advanced technique that involves the use of both hands in a slow and controlled manner. The high-quality finish and versatile nature make it a common choice for welding aluminum and other metals.

Thermal conductivity and porosity are also major concerns when welding aluminum versus steel. To combat these concerns, argon gas, or a combination of argon and helium gas, is used as a shield when welding aluminum.

The way you weld aluminum is also different in that a weave technique is typically not recommended. Instead, a simple push technique is usually ideal. You’ll need to start with a very clean surface for aluminum and always remove any oxide layer that has accumulated to avoid contaminating the weld pool.

• Auto-darkening helmet. This will help protect your eyes when you’re welding.
• Safety glasses. Look for models designed for welding.
• Leather TIG welding gloves. These are ideal for welding aluminum and are purpose-specific for TIG welding.
• Leather welding jacket or apron. Make sure the fit is tight, but not restrictive. Excess material is not recommended for welding.
• Blue jeans or specific work pants without a cuff. Durable denim is an excellent option for welding.
• Work boots or shoes. Leather is a preferred material for welding. Make sure the tread is not worn or damaged and able to provide stable footing as you work.

Aluminum welding is a specific job, and not just any gear will do. Along with task-specific equipment, you’ll also need to purchase the right safety equipment to avoid putting yourself at risk.

• Welding machine. The right welder is essential if you’re going to work with aluminum. For aluminum, a TIG welding machine is a better choice than a MIG (metal inert gas) machine. While MIG machines can be used, TIG machines are preferred by most professionals taking on complex aluminum welding tasks.
• Welding torch. You’ll want to use a separate liner for aluminum if you work with other materials as well.
• TIG welding electrodes. Check your welding machine for the proper type. Pure tungsten electrodes are commonly used in TIG machines, but some do vary.
• Aluminum rod fillers. These are needed to bond two pieces together. Look for 4043 and 5356 alloy types for most jobs. You’ll want these to be the same size as your TIG welding electrodes. These are commonly referred to as welding consumables since they burn up during use.
• Aluminum welding wire when MIG melding. ER 4043 or ER 5356 is ideal for most jobs. Match your rod filler to your welding wire.
• Argon gas canister. Argon gas is used as a shield during the welding process. For some jobs, a mixture of argon and helium can be used instead, but this is very much job dependent.
• Wire feeder. A constant torque, variable speed motor wire feeder cabinet is ideal when using the push method of aluminum welding.
• Wire cleaning brush. You’ll need this to prepare the surface of any metal you’re going to be working with.
• Temperature indicator. This will help you during the preheating process which is essential to avoid weld crack, especially when working with large, heavy or thick pieces of aluminum.
• Welding tips. You may need different sizes based on different jobs. Use certain tips for aluminum only if you do other types of welding.

With all of your tools and supplies ready, it’s time to do some actual aluminum welding. Learning how to weld aluminum can be tricky, so it’s always best to have somebody knowledgeable explain the smaller details.

• Begin by cleaning the base metal that you’re working with.
• Doing this with a wire brush – used specifically for aluminum welding – can help remove aluminum oxide that has a much higher melting point than the base metal. You may also use an etching solution, but special precautions need to be taken if you do.
• Preheat the piece of aluminum that you’re working on to help prevent weld cracking.
• Avoid preheating over 230 degrees Fahrenheit. Use a temperature indicator to guide you.

• Use the push technique when welding aluminum. Do this by pushing the welding gun away from the weld puddle instead of pulling it or using a push-pull method.
• Use hotter settings in terms of amperage and voltage. Aluminum tends to benefit from higher weld travel speeds.
• Pick welding wire that has a melting point similar to the base material that you’re working with. A larger wire diameter is usually easier to feed through your wire feeder, resulting in less snags and slowdowns.
• Choose a welding tip about 0.020 inches larger than the diameter of the filler metal that you’re going to use.
• Welding aluminum is a special skill, and too much heat can actually blow right through your material.
• Work slowly and you’ll be less likely to experience problems.
• As always, follow proper safety precautions and check your equipment regularly. If you’re unsure of how safe a certain tool or task is, seek help from an experienced professional before you begin.