The welding process is widespread in many manufacturing industries. From automobiles to aerospace – you’ll see many parts made through welding. It is an excellent way to connect and join two metal sheets. However, there are different types of welding in sheet metals. Those types differ in their working and overall performance.
Generally, people are familiar with the types of TIG and MIG welding. However, the world doesn’t end here, as there are some other types as well. Understanding all these types will help you select the most suitable method for your welding needs. In this article, I’ll explain the types of welding that are widely used for joining metal sheets. Let’s get started!
Overview of Metal Sheet Welding
Welding is the process of joining two or more parts or materials by heating them to a suitable temperature. The welder generates extreme heat, melting the edges of the material. When the material cools, the edges of the two parts join together, forming visible joints. This joining of two parts is called welding. The process is highly dependent on the heat.
Thicker materials are generally easier to weld. The reason is that they can sustain the heat and undergo warping. However, the metal sheets are thin and flat. Due to thinness, they are susceptible to heat. When welding thin sheets, the chances of warping are very high. Therefore, welding metal sheets requires skills and specific welding machines.
You might wonder why we need to weld metal sheets, as we can use thicker material. Remember, the automobile and aerospace industries need metal sheets to make some of their parts. Thicker materials can increase the weight of aircraft or vehicles. Those heavier parts will also make the cars consume more fuel.
Interestingly, there are different types of welding available. However, their working and usability differ from each other. They utilize various sources to generate heat, which is used to melt material and create joints. Remember, sheet metal can be made of different materials, such as aluminum and steel. Each sheet will need a specific type of welding procedure.
Types of Welding in Sheet Metal
As I mentioned earlier, various welding techniques are available. Some of those are ideal for thicker metal sheets. On the other hand, a few welding types are best suited for thin sheets and don’t create burn-through. Every welding type has its unique advantages, disadvantages, and specific applications. Let’s dive deeper and discuss those types and how they are helpful for welding metal sheets.
1- TIG Welding (GTAW or TIG)
TIG (Tungsten Inert Gas welding) is a popular method of welding metal sheets. It is considered ideal for creating welds on thin metal sheets due to its precision. It uses tungsten electrodes, which are non-consumable during the welding process. This process uses an electric arc to melt the material.
Remember, this arc can provide temperatures up to 6000 degrees Celsius. This high temperature can melt any material with ease. This method utilizes a separate filler material, as it employs a consumable electrode. During work, the machine generates an electric arc. This arc is directed to the area where welding is required.
The operator uses filler material to help create a strong weld in the desired spots. The TIG method uses argon as a shielding gas. These gases help prevent complications such as air contamination during the welding process. As the operator can manually feed the filler, they gain more control over the welding process. So, he can create smooth welds in the desired location.
By controlling filler feeding, he can ensure that the other part of the sheet does not heat and expand. The advantage of this method is the precision of the weld. Remember, the welding machine does not automatically feed filler. The operator directs the filler to the desired location. This results in a strong weld with exceptional precision.
The process is considered ideal for welding aluminum or stainless sheets. It directs the heat exactly where the weld is needed. So the other portion of the sheets doesn’t get heated. If that happens, the welded spot can undergo warping. However, this process is expensive due to the use of a separate filler. The involvement of human efforts in feeding filler makes this process slower.
2- MIG Welding (GMAW or MIG)
MIG (Metal Inert Gas welding) is another method that is less precise than TIG. However, it is inexpensive and quicker, which makes it a decent option for metal sheet fabrication. The MIG welding method uses metal wire as an electrode. This electrode is consumable and gets used during the welding process. In simple words, the electrode itself acts as a filler material.
The welding gun uses wire metal (an electrode) as a filler material during the welding process. The electric arc coming from the electrode melts the metal sheets. The filler material is used on this spot, fused, and a weld is created between the two parts. Unlike TIG, this welding technique does not use a separate filler material. The welding gun continues to use the wire electrode independently.
There is no human involvement in feeding the filler material. This results in faster welding and quicker manufacturing of parts. However, there is a drawback of no human involvement. The electrode (filler) is used automatically by a welding gun. So, welding guns without an operator can be used in the wrong place. Therefore, it can affect precision and create large, unsightly, and undesirable welds.
Remember, the metal sheets are sensitive to heat. If the welding gun does not heat the accurate spot, it can result in the expansion and warping of the material. Additionally, this automatic feeding of electrodes as filler material can create large-sized welds. This large weld can affect the appearance of the material. This method is considered suitable for welding thicker material.
3- Laser Beam Welding
It is a modern welding procedure that uses a high-powered laser to create welding on metal sheets. The laser welding machines come with a dedicated laser source and laser head. When you switch on the machine, the laser source produces a high-energy laser beam. The laser head then directs this laser at the desired spot.
As the laser has high energy, it melts and fuses the parts, creating a weld. Both manual and automated laser welding machines are available. Computerized machines are more precise than manual welding machines. I consider this method best suited for thin metal sheets. Let me explain the reason.
The laser head directs the laser to the desired position. The laser itself is a very concentrated, narrow beam and does not heat the whole material. Instead, it remains focused on specific spots. As a result, it does not cause the material to expand or warp. Moreover, the intensity of lasers can be controlled, which helps avoid burning through the metal sheets.
4- Spot Welding (Resistance Welding)
This type of welding is used to manufacture sheet metal for car doors, roofs, frames, and other parts in refrigerators. In this method, pressure and heat work together to create the weld. The first two metal sheets that need welding are taken. They are placed in a way that the portions where welding is to be made should touch each other.
Two electrodes are then pressed on these parts from the top and bottom positions. In this way, the parts don’t move or shift out of alignment. Now, you’ll have to switch on the spot welding machine. As a result, the machine will send the electric current to the copper electrode. This current will then flow to the position where the two materials are in contact with each other.
You’ll have to apply pressure as the current melts the sheets at the contact point. This will create a strong and durable weld that lasts many years. This current provides the required heat, melting the touched part and creating a weld. This welding process is widely used on a large scale. Many automobile parts are made through this procedure. This type can create clean & smooth welds on metal sheets.
Quick Highlight: Remember, the heat is transferred to the touching portion of the metal sheets. As a result, it creates a perfect weld between those sheets. What I love about this method is that it does not make a large HAZ (Heat Affected Zone). Heat is supplied to the position where the weld is needed. No other portion receives heat, expands, or warps during this welding process.
5- Plasma Arc Welding (PAW)
This method is similar to TIG welding and offers extreme precision. It also uses tungsten electrodes (non-consumable). However, plasma (super-hot gas) is used to melt the metal sheet instead of an electric arc. In this welding machine, the electric arc is first produced.
The gas, such as argon, passes through this arc, heats, and becomes plasma. This plasma then goes on between the electrodes and the metal sheets. It melts the metal edges quickly, fuses them, and creates a strong weld. Remember, this method is costly and premium. Only large factories and manufacturing units utilize these welding types.
Remember, plasma welding is a very complex procedure. Only those who already know how to weld using this method. Plasma welding indeed offers welding with exceptional precision. Moreover, the chances of warping and heat distortion are also low. However, if misused, this welding procedure can even damage the metal sheets.
Frequently Asked Questions
What type of welding is used for sheet metal?
Generally, TIG and MIG welding are popular types used in metal sheet welding. TIG is best suited for thinner sheets and produces small, strong welds. The MIG welding is best suited for thicker metal sheets where weld size does not matter.
What are the four main types of welding?
There are multiple types of welding procedures available. However, we use a few of them for welding metal sheets. Here are their names:
- Plasma Arc Welding
- Laser Beam Welding
- Spot Welding (Resistance Welding)
- MIG (Gas Metal Arc Welding or GMAW
- TIG (Gas Tungsten Arc Welding or GTAW)
Is welding a metal sheet easier?
No, welding metal sheets is a challenging process as sheets are sensitive to heat. They can undergo warping, heat distortion, and burn through due to high heat. Therefore, special welding techniques are used with precaution to create a smooth and strong weld.
Conclusion
Welding is a crucial procedure widely used in metal fabrication. It helps create a strong weld (or joint) between two materials, joining them permanently. However, there are different types of welding methods available that differ in their working. Determining which welding method is suitable for metal sheets can be a confusing process.
In this article, I’ve discussed the five most popular welding techniques that are ideally suited for thin metal sheets. Remember, those methods that create a large HAZ (Heat Affected Zone) are not suitable for metal sheets. If you use such methods, your metal sheets will undergo warping, resulting in wrong welds.