How to Weld Aluminum with a Stick Welder?
Aluminum is a very important metal in the welding fabrication industry. The engineering applications of aluminum were recognized in the 19th century. It now plays an important role in the automotive industry. Aluminum can now be welded to make complex structures. There are various methods for aluminum welding. But if you know how to weld aluminum with a stick welder, you will be able to weld aluminum efficiently.
Properties of Aluminum:
Aluminum is lightweight and soft. It can be easily cast, formed or welded. It can be joined with other metals easily by welding. Aluminum has a high resistance to corrosion, and it has good electrical and thermal conductivity. Aluminum has a low melting temperature (6600C) and high thermal conductivity.
Cleaning and preparation:
As aluminum quickly forms a thin layer of aluminum oxide when it gets in touch with oxygen in the air, this layer must be removed before welding. If possible, you should prevent the formation of the layer. To prepare the aluminum for welding, you should scrape the thin layer off using a sharp too or sand paper.
Aluminum Welding with a stick welder
In the past, many people have used the TIG welding method for aluminum. Cheap TIG welder for aluminum is still widely available. But recently, other methods like MIG welding and stick welding methods are gaining popularity. These methods require less training and can produce high-quality welds.
Aluminum Welding using welding rods is one of the most used welding methods. Stick aluminum welding is a good choice for repairing pipes and tanks. Here are some of the things you should know about welding aluminum with a stick welder.
- Stick welding joins to metal pieces using an electric arc. This produces intense heat and melts the metal parts.
- If it is melted with a coated electrode, the metal gets mixed with a filler. This joins the two metal parts into one unit.
- In stick welding, you need to use an aluminium-coated electrode.
- The welding process is very quick, and it doesn’t let the metal to come into contact with the arc too much.
- In stick welding, a heavy dipped flux coated electrode is used along with DC Reverse Polarity.
- The flux coating acts as a gaseous shield for the arc and the molten aluminum. It also removes the aluminum oxide.
- Some flux vaporizes in the arc for forming the shielding gases. This stabilizes the arc and shields them from the surrounding environment.
- The current and polarity settings of the electrode depend on the type of electrodes.
In this welding process, controlling the arc is a challenge. Another problem is the corrosion caused by the flux entrapment. The welds can be prone to porosity.
Aluminum vs Steel welding
Unlike steel, you won’t notice any colour change in aluminum as it reaches the melting point. Once above the melting point, you will notice a dull red colour. Most of the welding processes don’t let aluminum go above the melting point. So, the original colour of the aluminum is retained after welding.
Another difference between aluminum and steel is that the aluminum reacts with oxygen in the air and forms a thin and hard film of aluminum oxide. The melting point of aluminum oxide is about three times higher than that of aluminum. The aluminum oxide absorbs moisture and causes porosity affecting the weld strength.
Aluminum can conduct heat faster than steel. However, it requires more heat to weld and so preheating is sometimes necessary, particularly when welding thicker sections. High heat conductivity allows aluminum to solidify quickly. The thermal expansion of aluminum is more than that of steel. When aluminum solidifies after welding, it’s volume decreases by 6% causing distortion and cracking.
The breakthrough of aluminum welding took place after the invention of inert gas welding process during the 1940s. The inert gas protected the molten aluminum during the process of welding, and so it was possible to get high-quality welds fast. There are many ways of welding aluminum, but using one system consistently will help you to avoid defects and burn-through problems.
The properties of aluminum make it difficult to weld compared to steel. This is because it expands more than steel when heat is applied and melts easily due to its low melting point. But if you use the correct temperature to weld and pay attention during the entire process, you can weld aluminum without any difficulty.