Welding aluminum is the name of a nightmare for most welders, especially if you’re a novice beginner. The surface of the aluminum forms an aluminum oxide cover on it when the metal exposed to oxygen. The aluminum oxide’s melting point is 2000° C, whereas the aluminum itself has a melting point of 660°C (learn more about it from welderfreak.com if you’re interested).
This unmatched melting point of both can make it super hard to weld properly, no matter which welding method you use. Stick welding is one of the easiest and the most popular methods that anybody can get familiar with within a short period. Although MIG or TIG welding methods have better diversity in welding aluminum, stick welding methods also can do the job just fine. You have to know how the method works on aluminum and how you can land a seamless joint on the piece.
How to weld aluminum with a stick welder
Welding aluminum with a stick welding method may seem strange, especially if you have never done it before. Here, I’ll help you weld aluminum with a stick welder that you may already have instead of getting a new welder.
Put on safety gear before welding
Before you start working with a piece of aluminum and try to weld two pieces together, it’s important to know your dealing. As I mentioned earlier, welding aluminum is different from other materials, so you will work with it in stages. Put on a full sleeve welding jacket and a pair of welding gloves to avoid the heat issues while welding. Be sure to use a welding helmet to avoid any hazard while welding, especially sophisticated metal like aluminum. It may have more spatter and uneven welds the first time, so it’s important to protect against the potential hazard.
Cleaning and preparing the material
Let’s put; aluminum is the type of metal that you cannot treat the way you treat any other metal while welding them. You must clean the aluminum workpiece before you weld them together thoroughly to expose the aluminum oxide. Use a stiff stainless steel wire brush to clean the aluminum’s surface and make sure there is no dirt on the joining area.
Once the pieces are clean and ready to weld, if it’s a T-shape joint, you can also join the corners before you start the main welding. It will help you keep the pieces firm in their places without touching or clamping them on the table because it may feel gummy. If it’s an outside welding job, be sure to get the best cleaning ideas from welderfreak.com.
Preheating the pieces
As I mentioned earlier, aluminum has an uneven heat dissolving point on the surface and the inner layer. Furthermore, aluminum can dissipate heat much faster than other materials, so you have to work properly for the best result. Preheating the aluminum will help you get it to a middle point where you can easily penetrate the metal. Take an oxy-acetylene torch and set the flame to a carburizing type by turning the lever to an initial point.
Torch the workpiece, cover the whole area you’re going to weld, and keep heating until it develops a black layer. Now, turn the heat up to a neutral flame at about 400° and torch the piece until the whole black layer goes away. Take a temp stick and see to check if the temperature has raised; if the temperature is over 250°, the piece is preheated.
Prepare the welding machine and the electrode
To weld aluminum with a stick welding machine, you have to set the current on DCEP (Electrode Positive) Reverse Polarity. It will have a good penetration if you preheat the pieces and use the right electrode stick with the right coating. The best option will be going with a low hydrogen electrode, although they can tend to give in a rough start. The reason behind the rough start is because they come covered with the flux on the starting end. You can slightly minimize the rough start by hitting the starting end to metal and expose the bare electrode from the protective flux.
Weld the aluminum and end the properly
Once you have your machine ready and the stick electrode ready to go, you can now start welding the pieces. Start welding the piece from your side and start with a push welding process, you’ll have more control this way. Of course, you can pull the weld as well; but you will have less control over the joint. Before you stop welding, one thing you must not forget is the ending process! Many folks make a mistake and run directly through the ending, but the best practice is, once the weld is done, take a moment and pull it back a bit. It will give the joint more rigidity and prevent future cracks, especially if the joined pieces vibrate a lot.
Cleaning the weld
You will get a lot of spatter around the joint, and that’s natural when you’re sticking welding aluminum. There will be a thick layer of protective flux on the molten puddle, which you have to chip off after joining the pieces. After the joint, let it cool down, take your chipping hammer, and start getting the flux layer off. Some unwanted solid welds may develop off the joint; you have to grind them off with a wire brush if you need a clean weld.
If you have a stick welder and plan to weld aluminum with it, it can be difficult to understand the process. However, once you understand the process and practice a bit, it will become much easier, and you’ll be able to control it properly. Before welding, don’t wait too long for the pieces to cool off; they may become too cold because aluminum dissipates heat four times faster than carbon steel.
Attach the electrode to your stick electrode holder properly; use the one I’ve mentioned earlier with the aluminum electrode inside. They can be expensive and melt pretty quickly, but they do the job the best on aluminum. You can learn about the other options from welderfreak.com, along with different electricity settings for them.