Joining materials together is an art that is very important to the construction and manufacturing industry. Welding joins metals or thermoplastic through softening them by heating and then applying pressure to make them stick.
While there are numerous types of welding techniques, each method works well for specific types of metals.
Among the prominent types is the stick welding technique. This method is part of arc welding and has been in use for quite some times.
WHAT IS STICK WELDING?
Stick welding is a method of joining metals by use of an electrode and electric current. Also called shielded metal arc welding (SMAW), this is a versatile method as it can be used for joining different types of metals. And, unlike other methods, this method is simple to learn.
Usually, the electrode is made up of a solid metal rod or a stick coated by compounds and metal powders. To make the compounds stick on the surface, they come to a binding agent.
While making an electric arc between the electrode and metal, a welder can use either direct or alternating current. The electrode conducts the electric current to the arc and provides filler metal for the joint.
Stick welding has extensive application in the maintenance and repair, and construction industries. Industries. It is best suited to for welding steel and iron. However, it works well for aluminum too.
STICK WELDING PROCESS OVERVIEW
Stick welding utilizes a flux coated electrode to generate a weld. Electricity passes through the coatedelectrode, making arcs at contact points with the base metal.
When the melting of electrodes begins, the flux coating around it creates a cloud of gases. This gas shields the molten metal and prevents it from oxidizing. For this reason, it is called shielded metal arc welding.
A cloud of gas settles on the pool of molten metal as it cools. This gas turns into a slag which must be chipped off after welding is complete.
Advantages & disadvantages
STICK WELDING ALUMINUM
Stick welding aluminum can confusing. More often, some sources say that you need either an AC TIG welder or a MIG welder with a spool gun and an argon shielding gas to weld aluminum. This is not entirely true.
Here’s the deal:
AC TIG using argon is the slowest, cleanest and most controllable way to weld thin sheets of aluminum. On the other hand, DC TIG with helium can weld aluminum, but its hot arc and deep penetration work well for thicker welds.
MIG, which is DC is much faster than TIG, but the process requires a filler metal to melt the base metal. This makes the process complicated.
For straight MIG cables, a spool gun or push-pull gun is not a necessity.
HOW TO WELD ALUMINUM WITH A STICK WELDER?
The welding and fabrication industry usealuminum metals extensively. This metal plays a huge role in the automotive industry. With advancing technology, aluminum can be welded to make complex, appealing structures.
First,let’s look at the features of aluminum.Understanding these properties will make get the best welds.
PROPERTIES OF ALUMINUM
Aluminum is a soft and lightweight metal that can be easily cast or welded. For a fact, you can join aluminum with other metal as it is easier to weld.
Note that aluminum is resistant to corrosion, has excellent electrical and thermal conductivity. Besides, the melting point is a bit lower – 660 degree Celsius, while the thermal conductivity is high.
STICK WELDING PROCESS
The use of welding rods in welding aluminum is one of the most commonly used methods. The method is efficient and faster.
Stick welding is a common method and has been used to extensively in repairing tanks and pipe. The basics of stick welding are:
- Stick welding joins two pieces of metal by using an electric arc. This produces intense heat which melts the metal parts.
- If a coated electrode is used in the melting process, the metal will mix with the filler to join the 2 metals into a single metal. In this case, an aluminum-coated electrode will work well. Besides, this process is rapid: the metal doesn’t come in contact with arc for long.
- For DC reversed polarity, a heavily flux-coated electrode is preferred. The flux coating act as a gas shield for the arc and the aluminum that is molten, preventing oxidation.
- The current and the polarity settings of the electrode depends on the type electrode.
- Remember, in this welding process controlling the arc is a bit challenging. Also, this welds can be prone to porosity due to the corrosion caused by flu entrapment.
Learning how to weld aluminum with a stick welder, is rather straightforward if you understand the behavior of aluminum.
Aluminum is a good conductor of heat. However, it requires more heat to weld than other types of metals. In this case, pre-heating can be a necessary step, especially when dealing with thicker metals. The advantage of high heat conductivity allows aluminum to solidify quickly. Upon solidification after welding, the volume of aluminum decreases by 6 percent, which always results in distortions and cracking.
Aluminum reacts with oxygen forming a thin layer of aluminum oxide. This layer is robust and has about three times higher melting point than aluminum. This layer absorbs moisture and causes porosity affecting the strength of welds.
Aluminum welding is possible because of the use of inert gases such as argon. The importance of the inert gas is to protect the molten aluminum during the process of welding. This results inhigh-quality and consistent welds within a short time.
Much as there are many methods of welding aluminum, having a consistent system is essential in producing the best results: devoid of defects and burn through problems.