Aluminum is a challenging metal to weld, but especially with an arc welder. Aluminum requires you to use specific equipment and techniques to achieve a high-quality weld.
Can you weld aluminum with an arc welder? Yes, you have to clean and preheat aluminum before you weld it with an arc welder. Because using an arc welder with high amperage can distort or burn through aluminum, you have to set the amperage to a lower setting.
Arc welding is more dominant than any other welding process used in the world, but it’s difficult to use stick welding on softer and thinner metals. No matter which process you use, aluminum is troublesome for all welders. With a low melting point and a high thermal conductivity, aluminum requires a great deal of practice and patience to weld.
Unlike carbon steel, aluminum does not change color before it reaches the melting point. This unique property makes it harder to follow the weld pool. If you want to weld aluminum with an arc welder effectively, you must clean and heat the aluminum and use a faster travel speed.
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How Do You Weld Aluminum With an Arc Welder?
Welding aluminum with an arc welder is not a simple process. Amateur welders may become frustrated with aluminum when they first attempt to weld it.
Before you continue reading, here is an article we wrote about 8 Reasons Your Aluminum Welds Are Black – How to Avoid Them
If you’re new to welding, you’ll probably have to practice several welds before you get the hang of using a stick welder on aluminum. The following list displays the steps you need to weld aluminum with an arc welder.
|Step – Nr.||Requirements|
|1||Prepare your workspace|
|2||Wear protective gear|
|3||Prep the aluminum|
|4||Preheat the aluminum|
|5||Weld the aluminum|
|6||Clean the weld|
1. Workspace Preparation
The ideal location to weld aluminum is outdoors. Unlike TIG or MIG welders, an arc welder is effective in winds up to 35 mph. Since stick welders use a flux-coated electrode rather than shielding gas, a light wind does not affect the arc’s weld pool.
If you cannot weld outside, try to weld in a room with ample ventilation. Using fans to blow the fumes out of an open window will work, but you can set up a fume extractor next to your workspace for more effective ventilation.
Before you begin welding, ensure that all flammable and combustible materials are removed from the area. Because a stick welder operates at high temperatures, it’s easy for a nearby oily rag or an aerosol can to ignite.
2. Wearing Protective Gear
Arc welding can be hazardous if you fail to take precautions before you begin welding. The temperature of the arc can range from 5000°F to over 20,000° F.
Although amateur welders seldom experience the higher temperature arcs, the lower temperature arcs are hot enough to crack concrete and inflict third-degree burns on uncovered skin.
Fire-retardant gloves and aprons are necessary if you want to avoid the danger from molten spatter and possible flare-ups. Welding gloves and aprons are inexpensive and should be replaced after frequent use. It’s a good idea to purchase a few pairs of gloves of you do a lot of stick welding.
Because you have to hold the electrode with your hand, your gloves will wear out quicker when you use an arc welder.
It’s unlikely that many welders use an arc welder without a helmet, but if they do, they may permanently damage their eyes. Since the glare from the arc is brighter than the sun, you put your health at risk if you fail to protect your eyes.
A bulky respirator may seem cumbersome under your helmet, but it gives you another layer of protection from toxic fumes. Although it may seem unnecessary with every project, once you get used to wearing it, your lungs will thank you.
3. Aluminum Prep
Unlike stainless steel, aluminum has a strong reaction to oxygen. The metal immediately reacts with oxygen and forms a layer of aluminum oxide on its surface. The aluminum oxide will contaminate the weld pool and inhibit the heating process if you do not remove it.
Scrape off the oxidized film with a wire brush or use fine sandpaper to remove the coating. Experts recommend avoiding the use of a powered grinder or sander on aluminum.
If you use powered tools to remove the aluminum oxide, you risk folding some of the oxides into the metal. You cannot perform a viable weld with aluminum oxide embedded in the surface of the metal.
4. Preheating the Metal
Since aluminum can dissipate heat four times faster than carbon steel, you must preheat the metal to 400°F before you strike an arc. A thermometer stick will help you keep the temperature below 400° F, but you can also use a trick suggested by an incredible welder in this video.
The trick involves darkening the aluminum with an oxyacetylene torch. To darken the aluminum with carbon, adjust your torch to a carburizing flame.
After your workpiece is covered in soot, readjust the flame by decreasing the oxygen content. Set the torch on medium and move it around the aluminum to heat it.
When the soot begins to disappear, your aluminum is at the right temperature for welding.
5. Welding Aluminum
Before you strike your first arc on aluminum, remember that you’re not working with steel. According to most experienced welders, aluminum is not a joy to stick weld. The arc reacts violently to aluminum and expels a lot of spatter.
The flux from an aluminum electrode creates a mess after it cools. Unlike the slag from other electrodes, aluminum slag is a dense, dark grey mass that requires ample post-weld cleanup.
Set your machine to 85 amps and use DC reverse polarity. That means that your aluminum rod with use the positive current (DC electrode positive).
If you’re welding two pieces that form a 90° angle, you’ll have to angle the electrode to 45°. The stick’s angle will always follow the angle formed at the center of the joint. In this case, the joint’s angle is half of 90°.
Since aluminum flux can interfere with your arc strike, try removing a small amount of flux at the tip of the electrode. The flux has a similar consistency to salt, and it reacts wildly during the initial arc strike.
Perform two tack welds at either end of the pieces. This prevents the ends of the base metals from becoming distorted as the aluminum expands from the heat.
Strike an arc and use a brisk travel speed to finish the weld. Unlike steel, the arc is difficult to follow after the first strike. Aluminum does not change color before it reaches its melting point, but if you maintain a steady, low arc on the pool, your weld will hold up.
6. Post-Weld Cleanup
Before you begin chipping away the slag, quench the metal by submerging it in water. Aluminum slag is almost impossible to chip off when it’s warm.
Use a chipping hammer to remove the majority of the slag and finish with a wire brush. The beginning of the weld may require more chipping than the rest of the weld. The initial violent reaction of the flux with the molten aluminum sometimes results in a wider weld in the beginning.
Use a dry cloth to remove any remaining slag flakes.
Aluminum Stick Welding >> Check out the video below
Is There An Easier Way to Weld Aluminum?
If you have a MIG welder, you may have more success and less downtime when you weld aluminum. MIG welders operate at lower temperatures than stick welders and are more suitable for smaller, more detailed projects.
The Absence of Flux
Since MIG welders use shielding gas rather than coated electrodes, they produce cleaner welds on aluminum. The ideal shielding gases for MIG welding aluminum are helium (75%) and argon (25%).
Unlike arc welding on aluminum, you will not have to preheat the aluminum before you MIG weld it. However, you will have to scrape off the oxidized residue before you weld. The weld pool will become erratic if it comes in contact with aluminum oxide.
Related reading: How to Weld Aluminum at Home >> A Beginner’s Guide
The irritating slag you have to remove when you stick weld aluminum is not an issue when you use a MIG welder. You will have to use a quick travel speed as you do with stick welding, but the resulting bead is cleaner and less labor-intensive to clean.
Most welders will agree that stick welding aluminum is a chore rather than a pleasure. It’s possible to produce a robust and lasting weld on aluminum with an arc welder, but it requires a fair amount of practice. If you can handle a tricky weld pool and an extensive cleanup process, arc welding aluminum may be for you.