Many of us are already familiar with the concept of welding, especially engineering students. And if you are a Mechanical engineer, you are more than aware of its idea and workings. In general, we can say that welding is the process where we join two or more parts of any material to give them a new shape. This unique material is different in shape and has relatively more strength than the previous one. These materials are mostly either metals or thermoplastics.
The people who perform the process of welding on these materials are welders. We use heat to complete this process. Sometimes, the pressure is also involved instead of heat, or both of them. The main objective of heat is to melt these parts so that they can fuse. The pressure is also applicable for achieving a similar result. When these parts cool down, they stick together and become a single entity. However, these parts do not stick together of their own accord, even when in melted form. We use some filler metals so that they join these parts together.
After applying heat, these filler metals melt and form a type of molten pool. When it cools, it acts as a joint between the metal parts. After the process of welding finishes, the result is termed as a weld. The selection of filler metal takes place by keeping in check the disposition of the weld. It can either be more challenging than the base metal or weaker than it. When the weld is ready, your task is still not complete. Since the weld is a metal, it is at a constant threat of corrosion or rusting. The metal can get oxidized if kept too much in the natural environment. To avoid this, a coating is done on the surface of the metal.
Since the onset of world wars, the process of welding has been in great demand. With ammunition requirements increasing, more and more welders started springing up. Currently, the most popularly used welding process is arc welding. It utilizes the current to produce heat, which in turn melts the metal. For applying the arc welding process on metals, we require a substance that helps mediate the current. We call this substance an electrode.
Welding Electrodes: A Rundown
During the time spent arc welding, we need to make an arc that goes about as a mechanism for the current to travel. In this cycle, you have a welding machine, metal parts, and a few wires. The stockpile of current isn’t immediate to the engine; instead, it goes through the wire. These wires are electrodes. We interface the inventory of wind with the electrodes, which at that point direct current. This current at that point goes through the whole length of the wire and arrives at the machine. This entry of wind is liable for the creation of an electric arc. In this manner, it is giving the cycle its name.
Nonetheless, when playing out the cycle of shielded metal arc welding, we don’t utilize electrodes. All things being equal, we like to use welding poles. In shielded metal arc welding, the bars don’t deteriorate to join the weld. Or maybe, they stay unblemished after the cycle. Attributable to their interest, a few welding bars are accessible on the lookout, Hobart welding bars being the most mainstream ones.
Based on their properties of disintegration, we classify electrodes into two basic categories. If the electrodes melt together with the base metal and become a part of the weld, they are consumable. Whereas, if the electrodes do not melt and are just present as a catalyst, they are non-consumable. The electrodes of the latter category are those with high melting points. This property enables them to resist melting under extreme heat.
Further classification of electrodes:
The above two categories are just the primary classification of electrodes. We can further divide these two categories into electrodes. These are according to different processes of welding, as well as their requirements.
Welders also call them to stick electrodes, as they use them in stick welding. Other processes which utilize the electrodes or rods are flux-arc welding and MIG. In these processes, the electrodes melt and become a part of the final weld. They act as a catalyst for the operation and as a part of the final product.
1. Light coating:
The name gives all the introduction you require about this. These types of electrodes do not have muscular coats. Instead, they have slight coatings on their surfaces. Since the layer is kept thin, the process of applying this coat is quite necessary and straightforward. You can either brush the coating on the surface or use a spray to apply the layer.
Now, what are these coatings made of? Basically, in these electrodes, we use layers that are quite similar to the base metals. You can use various substances to create these coatings. This thin coating is not only easy to apply but also has some benefits over thick layers. The final result of welding is mostly impure or gets in touch with environmental oxygen. But if you use a thin coating over the weld, it will protect it from getting impure.
Bare: Welders also know them as bare electrodes. As the name suggests, these electrodes do not have any coating on them. They do not have either of the layers, light or heavy. They are just direct electrodes. Due to this reason, welders do not use them much. Coatings on electrodes are crucial.
They not only protect it from impurities but also make the current propagation easy. Without the coatings, it gets quite challenging to control the present, as it often goes wary.
3. Shielded arc:
We use several coatings on electrodes, according to their type and requirement. The same is the case with electrodes that we use for shielded arc welding. There are three types of coatings that we use for this process of welding. The selection of an appropriate layer from these three is not a difficult task. All of them serve their particular purpose.
The first type of coating is the coating of cellulose. We apply a moderate amount of cellulose on the surface of the electrode. Since these electrodes later become a part of the weld, therefore the coating also joins it. Cellulose helps the weld’s body from getting impure by creating a protective layer of gas over it. Another type of coating is mineral coating. It produces slag, which in turn helps draw out the impurities to the surface of the metal. The last kind of coating is the one that involves both cellulose and minerals. They work together to create a layer of protection over the weld metal.
As compared to the above types of electrodes, these are pretty basic and easier to understand. It is because they do not become a part of the final weld. Instead, they only play the role of a catalyst during the process.
- Carbon: If you belong to the science stream, you may be well aware of carbon’s importance. Among all the elements in the periodic table, carbon is one of the most widely used parts. It is also a good conductor of both heat and electricity. Since we are dealing with electric current here, carbon is our best option for an electrode. It is also readily available and budget-friendly. The carbon electrodes mostly have graphite as their primary constituents. Sometimes, it has a copper coating, otherwise no coating.
- Tungsten: Welders use the electrodes made of tungsten in the process of TIG welding. According to the percentage of tungsten elements present in them, the coating of tungsten also comes in 3-4 types. We mark the layer of pure tungsten with green color. It is not applicable for many purposes as pure tungsten lacks strength and durability. Tungsten that contains some amount of zirconium has brown marks. Welders mostly use them when dealing with AC supply. Red and yellow marks suggest that the tungsten includes some amounts of thorium. These are the most popular among welders due to their durability and high resistance.
What precautions should you take while welding materials?
As welding involves the use of electric current, heat, metals, etc., it is quite dangerous. Whether you are a professional welder or a student, you should always remain precautionary during the process, especially when dealing with welding electrodes. The electrodes are wires that conduct electric current. Therefore, you need to keep them in a cool and dry place. Your electrodes should always remain dry and out of the reach of children.
After the process of welding finishes, it may take some time for the electrodes to dry out. Once they are dry, store them in a dry environment. Please pay attention that you do not leave them in direct contact with moisture. If the electrodes come in contact with water, it ruins their coating and affects their conductivity. So, keep them out of moisture’s reach as soon as they dry out. Several cases are available which lock out the water in the environment—store electrodes in these containers.
Try not to touch the electrode with bare or wet hands. The human body is a good conductor of heat and electricity. Therefore, if you touch the electrodes with your bare hands, you are in danger of feeling the electric current.