Aluminum Welding for Beginners

Aluminum Welding for Beginners

Aluminum Welding for Beginners

Learning to Weld Aluminum: AC vs. DC

Utilizing the right aluminum welding setup is crucial. To achieve an appropriate weld on aluminum, you must have an AC-capable TIG welder, such as the Mgder TIG. AC refers to what is known as “alternating current,” which is in direct contrast to DC or “direct current.” AC-capable aluminum welding equipment is preferred over DC because the alternating current has a positive half cycle that can provide a cleaning action, while the negative half cycle provides penetration. When learning to weld aluminum, AC TIG welders’ cleaning and penetrating capabilities are the best way to guarantee gorgeous welds.

THE TOP BENEFIT OF AC WELDING ALUMINUM

When learning to weld aluminum, it’s critical to be aware that aluminum requires comparatively higher temperatures to get a quality weld. When looking at TIG welding for beginners, you’ll find that these machines are more commonly used in the aluminum welding process due to their simplicity when compared to MIG welders. Because AC welding is the best power supply for TIG welders, most aluminum products are manufactured using AC welding.

AC PROVIDES BALANCE CONTROL IN TIG ALUMINUM WELDING EQUIPMENT

Prior to the 1970s, the negative and positive half cycle of alternating current was a simple 50/50 approach. Modern aluminum welding equipment now uses what is known as balance control for a more streamlined approach to create the ideal arc for all applications. As a beginner TIG welder working on aluminum, AC-capable machines that feature balance control are essential for making the job easier with better results.

When using AC current, the fluctuation between positive and negative poles occurs very rapidly. The term “alternating current” refers to this reversal in electron flow – something that doesn’t happen with DC. As mentioned, when you use AC aluminum welding equipment, you must control how much balance there is between the polarities. Running a TIG torch on a full DCEP (direct current electrode positive) balance will destroy the tungsten electrode and possibly the torch. DCEP places great heat into the torch and tungsten, while DCEN (direct current electrode negative) current places the heat into the workpiece.

For this reason, we need to be able to balance the polarity heavily to the DCEN side. Typically, this will average out to about 70%. However, there are exceptions to this – such as having oxidized or dirty base material. If you’re working with this type of material, it is essential to have the capabilities to adjust the balance more to the DCEP side, which allows the cleaning action to happen on the workpiece. The Mgder TIG 200 has a balance control built-in that works seamlessly, making TIG welding for beginners easier to manage. Balance control can be adjusted anywhere from 30%-70%, depending upon cleaning needs.

Four Top Aluminum Welding Techniques & Tips

Learning to weld aluminum is a complex skill that requires proper knowledge before you take on the task. Keep these aluminum welding techniques in mind to help you focus on the skills you need to master to get the job done right.

1. PREPARE YOUR ALUMINUM

Aluminum naturally forms a layer of oxide on the exterior surface when it cools off at a factory. Also, cleaning oils and contaminants can be left on the exterior when the aluminum is handled. The aluminum welding process will always begin by cleaning its surface before you even start thinking about turning on your TIG welder. Working on a clean work surface creates a noticeable difference in the quality of your weld. First, it’s best to use acetone to clean the surface and ensure it’s completely free of oils and any other contaminants. To remove the oxide layer, you’ll want to use a stainless steel brush. It’s not difficult to do, but if you skip using the acetone, you can push contaminants deeper in the material and affect the quality of your weld.

TIG welding tips for beginners always talk about the need to preheat your aluminum before getting started. Essentially, this step in the aluminum welding process will make it much easier to work with. Running a blowtorch over the aluminum before starting will minimize the amount of distortion you’ll often see when the heat of the welding torch creates a local hotspot on the material.

2. LEARN HOW TO SET UP A TIG WELDER FOR ALUMINUM

We’ve already discussed the importance of working with AC rather than DC, but learning to weld aluminum means understanding which electrode you should be using on your TIG welder. Your TIG electrode should always be pure tungsten, which offers better durability and purity than other electrode types. Your electrode should also not be sharpened to a point because the rough alternating current could cause it to break off into your weld. A common aluminum welding technique used by masters is using pure argon gas as your shielding gas. This creates optimal weld purity and performance when working with aluminum.

3. LEARN HOW TO WORK FAST

A particularly hard step in welding for beginners to master is speed. This is especially important for learning how to weld aluminum, as there’s a real danger of overheating your material if you take stops rather than moving on.

4. WORK WITH A HEAT SINK

Using a brass or copper heat sink is the best practice when learning to weld aluminum. Since aluminum transmits heat exceptionally well, clamping your project to a heat sink can take the heat out of the weld and allow you to be slower and more accurate. If your weld gets hot enough to start melting, the entire project can begin to shrink and warp. A heat sink is one of the best pieces of aluminum welding equipment to use as a beginner when you’re still trying to work on your speed.

Why Aluminum Welding Is Difficult

Aluminum is a common type of metal used in fabrication. It’s non-corrosive, lightweight and pleasing to the eye, making it an ideal choice of material for a wide variety of welds. However, the same traits that make aluminum desirable can also make it tricky to work with.

So why is aluminum so difficult to weld? This material is soft, highly sensitive and is insulated by a tough oxidized layer. While in its molten state, aluminum is susceptible to impurities, which can lead to porous, weak welds.

Aluminum and its alloys have a great affinity for oxygen. Pure aluminum melts at 1,200°F (650°C), and the oxide that protects the metal melts at 3,700°F (2,037°C). Because the oxide melts at a temperature approximately 2,500°F (1,370°C) higher than the aluminum itself, the oxide must be cleaned from the metal before welding can begin.

Since aluminum has a higher thermal conductivity and low melting point, it has a smaller window of workability than other metals and can easily lead to burnthrough. This, in combination with it being harder to indicate weld progress and quality, can make aluminum a difficult material to work with.

In sum, here are some of the most common factors that make aluminum challenging to weld:

  • Oxidation: On top of aluminum sits an aluminum oxide layer, which melts at a significantly higher temperature than aluminum. Melting through this layer requires high heat, however, the welder must be careful to not burn holes in the aluminum underneath.
  • Porousness: In its molten state, aluminum absorbs hydrogen quicker the more it heats up. This hydrogen separates out as the metal returns to a solid form, which can leave behind bubbles in the material, causing the metal to become porous and weak.
  • Impurities: As aluminum is very sensitive, there are several ways it can become contaminated by dirt, air and water during the welding process. Aluminum can become contaminated by air that reaches the weld because of poor shielding or excessively long arcs. Oxygen can reduce aluminum’s strength, ductility and cause an oxide formation on aluminum welds, which affects its appearance and complicates multipass welding. Hydrogen can come from many sources, such as moisture in electrode fluxes, humid air, damp weld joints and more. For all of these reasons, it’s important to clean aluminum thoroughly and store it correctly prior to welding.
  • Thickness: Welding aluminum involves working with different material thicknesses. Welders must know how to avoid burning through thinner material while also penetrating thick material enough to create a strong weld.

While there are certainly challenges that come with welding aluminum, it’s not impossible to learn. Luckily, there are tools and techniques designed to help when working with aluminum’s unique properties.

By having knowledge of the way aluminum reacts and how to effectively use these tools and techniques, you’ll be well on your way to mastering the art of aluminum welding.

Types of Aluminum Welding

GTAW/TIG

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is one of the most popular welding processes chosen for aluminum. This welding technique is often used by automotive enthusiasts and welders for professional racing teams.

GTAW requires a constant current equipment with AC (alternating current) capabilities using 100 percent argon as a shielding gas. It does not require mechanical wire feeding, which has the potential to create feedability issues.

Rather, the welder will feed the filler material into a puddle. This process is also very clean, as the alternating current cleans the oxidized layer off the aluminum as it welds. It also prevents aluminum from being contaminated throughout the process.

Tips for TIG welding:

  • Pick the right tungsten electrode or rod—the best choice for aluminum is typically a pure tungsten rod
  • Take the time to prepare your aluminum by cleaning and preheating it
  • Ensure there is not too much argon flow at the torch, which can cause an irregular arc
  • To prevent warping, use a heat sink
  • When welding, keep the proper aluminum filler electrode or rod free of contaminants and melt it with the base material to create a constant welding puddle

GMAW/MIG

Gas metal arc welding (GMAW), commonly referred to as metal inert gas (MIG) welding, is another common method used for aluminum welding.

This type of welding typically has faster travel speeds and higher deposition rates than TIG welding, affecting the weld quality. However, it does utilize a mechanical wire feeding system, which means the welder may have to use a spool gun or push-pull gun to make wire feeding possible.

Additionally, in order to combat the risk of aluminum becoming porous, the base material and filler rod must be clean, free of moisture and have excellent shielding gas coverage, typically pure argon content. Check out Lincoln Electric’s guide to aluminum GMAW welding to learn even more about this method.

Tips for MIG welding:

  • Prepare your push-pull wire feed
  • Clean your aluminum, remove any oxide and file the edges that will be joined
  • Avoid pulling while welding—instead, push at a 10 degree to 15 degree angle
  • Use multiple pass straight beads to improve the overall appearance of the weld and help to avoid defects
  • Use a heat sink, which will absorb extra heat and allow you to weld slower

Gather Aluminum Welding Supplies and Equipment

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 – tungsten inert gas – welding machine is a better choice than a MIG 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.

Aluminum Weld Pools Explained for the Beginner TIG Welder

Beginner TIG welders working on aluminum will notice that the weld pool of the material can look very different than when working on mild steel. The weld pool is orange and noticeable on mild steel. However, on aluminum, the weld pool looks more like a small, wet reflective puddle.

Understanding what this puddle should look like is one of the primary principles about welding for beginners to know. It can help you avoid overheating your workpiece while attempting to achieve a weld pool that simply will not happen. Controlling amperage while welding aluminum is very important. You can accomplish this by making good use of the foot pedal. There is often the need to continuously increase and decrease amperage while welding aluminum to achieve a symmetrical weld pool.

For this reason, you must have a TIG welder with a quality foot pedal. The foot control included with the Mgder TIG 200 package is another reason it can be considered one of the best welding machines for aluminum. It is made to be highly durable, and it consists of high-quality steel and electrical components. It also responds exceptionally well to slight changes and is comfortable to use for long periods.

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