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What is Welding and Its Major Types? A Complete Overview

Welding

Welding is a quite common manufacturing process used in various areas. Generally, whenever the word “welding” appears, people assume it is a process that involves the joining of metallic materials together. Its primary purpose is undoubtedly to bind the materials, yet the actual process is much more complicated than that.

There are various types of welding that follow the same working principle but differ from each other at some points. This article will teach you about the detailed welding working procedure and its types. Hopefully, in the end, you’ll be able to differentiate among all the types without any query.

 

What is Welding?

Welding is a manufacturing process and technology that binds metals, thermoplastics, and even wood together by using high heat, pressure, or sometimes both. In the case of heating, the metal melts, and thus, after cooling, it forms a strong weld.

Besides this welding definition, there are more terms to learn to understand the welding process properly. The base material is a term that indicates the part that you need to join. Sometimes, additional materials, known as consumables or fillers, are added to form the joint. Plus, a fully completed joint that has undergone a welding process is called weldment.

 

How Does Welding Work?

As the welding process includes fusion and non-fusion welding, both work in joining the materials but in different ways. The fusion welding process is far different from the metal-joining techniques that use binders, such as brazing and soldering.

Most probably, the welding works by following three effective methods: fusion welding, pressure welding, and brazing and soldering.

Fusion welding primarily works by heating the material to fuse more than one material. The workpieces are heated until they reach melting point. Once the material is melted, it forms a firm joint after cooling. It can be done with as well as without filler material.

The second method is pressure welding, in which external pressure is applied to the material, and explosion or friction is responsible for producing heat. There is no temperature restriction. You may provide the temperature below or above the material’s melting point.

Brazing or soldering is another welding method. It doesn’t melt the base material like other welding methods. Instead, the filler material is heated to its melting point. Usually, the melting point of filler metal is lower than the melting point of base metal, due to which it melts before. The only difference between brazing and soldering is that brazing is performed at a temperature above 450°C while soldering works below 450°C.

In addition to welding metal, you may also weld plastic and wood. Typically, plastic welds demand the preparation of the surfaces, and then heat or pressure acts on them to provide binding. However, in the case of wood welding, it is essential to put the workpiece under pressure before the application of heat. The linear friction movements are responsible for the creation of joints.

 

What are the Major Types of Welding?

Apart from the three above-mentioned significant types of welding, in this section, we’ll further talk about the nine sub-types of welding methods.  Though the list of welding types goes pretty long, four of them are the most popular, which fall in the category of arc welding, i.e., MIG, TIG, Stick, and Flux-cored welding.

The following table shows the classification of welding according to the three major welding types:

 Major Methods of Welding Sub-Types of Welding
Fusion Welding Electrical Energy

●      Arc welding

1)     MIG-Gas Metal Arc Welding

2)     TIG- Gas Tungsten Arc Welding

3)     SMAW- Stic-shielded Meral Welding

4)     FCAW- Flux-cored Arc Welding

5)     SAW- Submerged Arc Welding

6)     Plasma arc welding

●      Electron beam welding

Chemical Energy

●      Gas welding

Light Energy

●      Laser welding

Pressure Welding Electrical Energy

●      Resistance welding

Mechanical Energy

●      Cold pressure welding

●      Friction welding

Brazing/Soldering Chemical Energy

●      Torch brazing

Light Energy

●      Light Brazing

 

Let’s jump on the first welding type!

A.   Fusion Welding

1. Arc Welding

Arc welding is the most comprehensive type of fusion welding, including various processes. Arc welding relies on the electric arc to melt both the workpiece and filler metal. Either a DC or AC power supply is responsible for the creation of an electric arc. Once it is generated, the metal base and filler material melts to make a strong bond.

The filler metal is continuously fed as the rod melts to make the process smooth and steady. However, to ensure a strong weld, you must move the arc moderately because the too fast or too slow speed may affect the quality of the weld.

The following are the subtypes of arc welding;

  • MIG – Gas Metal Arc Welding (GMAW)

If you’re a beginner striving to learn welding, starting with MIG is an excellent idea as it’s the easiest and cheapest one. MIG welding can be further done in two ways: by using a bare wire or a flux core.

Typically, a thin wire acts as an electrode continuously fed through a wand during MIG welding. At the same time, shielding gas is expelled around it to protect the weld from impurities. The wire melts and becomes filler metal as soon as the arc is generated from the wire tip to the base metal. Finally, the weld is completed. MIG welding is used chiefly in the construction and automotive industries for its compatibility with a wide range of metals.

  • TIG – Gas Tungsten Arc Welding (GTAW)

TIG welding counts in a few welding types that can work without filler metal. It uses a non-consumable electrode that is made up of tungsten. TIG welding utilizes a rod and a torch that produces heat to create an arc. Ultimately, the two metal pieces join with each other. Furthermore, the constant flow of gas is essential to offer protection to the weld.

Unlike MIG, TIG welding is a complex process, and high precision is required. Therefore, only professional and experienced welders should go for this type of welding.

Usually, TIG performs best with stainless steel, nickel alloys, aluminum, copper alloys, and magnesium.

  • Stick-Shielded Metal Arc Welding (SMAW)

Stick welding is the oldest type of welding, improving with the passage of time. The replaceable stick acts as the electrode and filler metal. An arc attaches the end of the stick to the base metal that creates the weld by melting the electrode into filler metal. To protect the metal from oxidation, the stick is coated with the flux that has the ability to make a protective gas cloud on heating. After cooling the flux, the gas settles on the metal, resulting in the slag.

  • Flux-cored Arc Welding (FCAW)

Flux-cored arc welding is somewhat similar to MIG welding. The difference comes in the wire acting like an electrode fed through a wand. In FCAW, the wire features a flux core. This flux core terminates the need for an external gas source by creating the gas shield around the weld. The lack of external gas sources makes it a cost-effective solution for you.

Flux-cored arc welding deals with exceptionally high temperatures; thus, it works better with thicker and heavier metals. That is why it’s usually preferred to repair bulky equipment. Additionally, you can go for the process outdoors without any risk. Yet, to get a neat finish, you must clean the leftover slag on the welded area.

  • Submerged Arc Welding (SAW)

One of the most commonly known arc welding processes is submerged arc welding. It also uses flux, but unlike FCAW, the arc area is protected from pollutants by a blanket of fusible granular flux. For a reason, it is submerged under powdered flux; it is known as Submerged Arc Welding.

Consequently, when a high temperature is provided for melting, the flux becomes conductive, and electrons start flowing between the electrode and the metal base. As an electrode, a solid or tubular-shaped consumable copper-coated wire is utilized. During the working process, you must ensure the continuous feeding of the wire.

You may avail both DC and AC to supply the power to weld. Primarily, SAW is preferably applicable in structural construction and industrial manufacturing.

  • Plasma Arc Welding

As the name indicates, this welding type consumes plasma. However, plasma arc welding is muchly related to TIG, as it can also work without the need for filler metal. Basically, the gas is pressurized into the wand, which in return produces plasma. Later on, the plasma ionizes, resulting in an electrical conductor. It proceeds as a small arc creation to melt the base metal.

Plasma arc welding stands out for its deep weld penetrating power and high-speed welding proficiency. On top of that, it allows you to deal with metal thickness up to 0.015 inches. Generally, this technique is used in aerospace applications.

2. Gas Welding

Gas welding is one of the oldest types of welding, and the reason for its popularity is its low expense. During the process, the heat is generated by burning a fuel gas, i.e., acetylene—the acetylene mixes with the oxygen to form a flame. When the flame strikes the weld area, it causes the melting of the material. Consequently, the liquid material diffuses into each other and makes a strong bond as it cools.

Typically, acetylene increases the temperature of the flame up to 3200°C. Although the temperature is not as high as in arc welding, it still offers excellent performance. Carrying out this type of welding process is comparatively easy.

3. Power Beam Welding

Power beam welding includes two categories: electron beam welding and laser welding. They both slightly differ from each other in some areas.

Electron beam welding works by generating electrons from an electron gun. These electrons are then accelerated at high speed and applied to the workpieces. Whereby laser welding makes use of photons. The monochromatic coherent light acts as a concentrated heat source that offers you high-speed welds in meters per minute.

The main aim of both electrons and photons is to provide kinetic energy, which is later converted into heat energy.

 

B. Pressure Welding

1. Resistance Welding

Resistance welding is a process in which the application of pressure takes part. Normally, you can weld two or more metal sheets by applying pressure and heat to them from an electric source.

Usually, copper alloy electrodes are made to contact the metal sheets. Afterward, welders apply electric current to these electrodes. In return, the electrodes transfer the pressure and heat to sheets and cause melting.

You may use resistance welding in the aerospace, construction, electronics, and automotive industries.

2. Cold Welding

Cold welding is a solid-state welding technique. Interestingly, it doesn’t need heat or fusion to join the metallic parts like other welding types. Rather, pressure is applied to create the weld.

Before you move for this type, make sure to remove the oxide layers from the surface of the workpiece. You may use wire brushing, some chemical processes, or other techniques to clean the surface. Once it is done, you may press the parts together. Cold welding is usually suitable for softer metals instead of harder ones.

 3. Friction Welding

Friction welding is also a solid-state welding process that requires no heat to weld. Instead, friction is created between the metallic parts by rubbing them at higher speeds and pressure. As a result, the heat starts generating at the point of contact. Hence, the bond develops in that specific area.

 

C. Brazing/Soldering

1. Torch Brazing

The torch brazing process consumes an oxyacetylene torch to melt the metal base and filler rod. As the melted liquid metal diffuses with one another, it forms a firm joint after cooling. The welder needs to manage both the torch and rod simultaneously to achieve highly precise welds. No doubt, torch brazing is pretty tricky and challenging to perform.

2. Laser Brazing/Soldering

As the name suggests, laser brazing uses a beam of light (laser) to join the sheet metal workpieces. Commonly, filler metal with a lower melting point is placed between or at the surface of metals to be bound. Later, with the help of laser light, heat is provided to the filler material; as a result, it melts down. Remember, in this subtype, only filler material is melted without affecting the parent metal.

Furthermore, in the case of laser brazing, the required temperature is above 450°C, whereas laser soldering works at a temperature below 450°C.

 

Advantages of Welding

The following are some advantages of welding; let’s have a look:

  • Allows you to get permanent and durable joints.
  • It provides a smooth and tidy finish to the workpiece.
  • You can weld the material in various directions and shapes.
  • The process can be used in multiple areas, including automotive, construction, aerospace, and many more industries.
  • Welding is a pretty budget-friendly technique that everyone can afford.
  • You can perform it both indoors and outdoors.
  • It consumes less time to complete and is more economical.
  • Requires less workspace and materials to start the process.

 

Conclusion

I’m sure now you have a basic understanding of the whole welding procedure and its various types. However, besides the benefits of welding, there are a few drawbacks that you need to overcome. Personal safety is the primary concern you must look for when welding the parts. To prevent yourself from sparks, it is wise to use fire-retardant clothes, glasses, and a helmet.

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