What is Welding Process ? Different Types of Welding Process ?

Introduction to Welding Technology :-

Welding technology involves the melting of metal to create goods. Welders work in a variety of different industries with many different pieces of equipment.It is a fabrication process used to join materials, usually metals or thermoplastics, together. During welding, the pieces to be joined (the workpieces) are melted at the joining interface and usually a filler material is added to form a pool of molten material (the weld pool) that solidifies to become a strong joint.In contrast, Soldering and Brazing do not involve melting the workpiece but rather a lower-melting-point material is melted between the workpieces to bond them together.
With the advent of technology, the process of welding has evolved over the years. However, it’s important to understand the differences between all the existing welding techniques in order to make an educated decision when it comes to picking the right welding technique for the job. Today many processes can be done by automated equipment, however some projects require professional help in order to manually customize the product. Welding requires work and practice, and it’s best learned with the assistance and guidance of professional steel fabricators.

Types of Welding :-
There are many different types of welding processes and in general they can be
categorized as:

Arc Welding: 
A welding power supply is used to create and maintain an electric arcmbetween an electrode and the base material to melt metals at the welding point. In such welding processes the power supply could be AC or DC, the electrode could be consumable or non-consumable and a filler material may or may not be added.

The most common types of arc welding are:

  1. Shielded Metal Arc Welding (SMAW):- A process that uses a coated consumable electrode to lay the weld. As the electrode melts, the (flux) coating disintegrates, giving off shielding gases that protect the weld area from atmospheric gases and provides molten slag which covers the filler metal as it travels from the electrode to the weld pool. Once part of the weld pool, the slag floats to the surface and protects the weld from contamination as it solidifies. Once hardened, the slag must be chipped away to reveal the finished weld.
  2. Gas Metal Arc Welding (GMAW):- A process in which a continuous and consumable wire electrode and a shielding gas (usually an argon and carbon dioxide mixture) are fed through a welding gun.
  3. Gas Tungsten Arc Welding (GTAW):- A process that uses a non consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by a shielding gas, and a filler metal that is fed manually is usually used.
  4. Carbon Arc Welding (CAW) :-Developed in 1881 by Nikolay Benardos and Stanislaw Olszewski, carbon arc welding is the first Arc welding process ever invented but is hardly used today as it has been replaced by more efficient and less dangerous processes such as twin carbon arc welding. The process welds metals together by heating them with a non-consumable carbon electrode, heating them to temperatures in excess of 3000 degrees celsius.
  5. Electrogas Welding (EGW) :- Invented in 1961, Electrogas Welding is similar to Electroslag welding in that the metal being welded is struck with a consumable electrode, without the use of pressure. Divergent from its ESW counterpart, in EGW the arc is not extinguished, and remains struck during the process. It is mainly used in the shipbuilding and storage tank industries.
  6.  Flux-Cored Arc Welding(FCAW):- As an alternative to shield welding, Flux-cored Arc Welding was developed. This welding process is quite similar to MIG or GMAW process, except for the fact that in FCAW a special tubular wire filled with flux is used and shielding gas is not always needed, depending on the filler. This type of welding is well-known for being extremely inexpensive and easy to learn. However, there are several limitations in its applications and the results are not often aesthetically pleasing as some of the other welding methods. The semi-automatic arc is often used in construction projects, thanks to its high welding speed and portability.
  7. Plasma arc welding (PAW) :- Plasma arc welding has ionized gases and electrodes that generate hot plasma jets that are aimed at the welding area. These jets are extremely hot. The concentration of higher energy is good for narrower and deeper welds as well as an increase in welding speeds.

In addition to Arc welding, there are a number of other welding methods that we’ll quickly through below.

Gas Welding: 

In this method a focused high temperature flame generated by gas combustion is used to melt the workpieces (and filler) together. The most common type of gas welding is Oxy-fuel welding where acetylene is combusted in oxygen. Resistance Welding: Resistance welding involves the generation of heat by passing a high current (1000–100,000 A) through the resistance caused by the contact
between two or more metal surfaces where that causes pools of molten metal to be formed at the weld area. The most common types of resistance welding are Spot-welding (using pointed electrodes) and Seam-welding (using wheel-shaped electrodes).

Resistance welding :-

This process involves applying force to adjacent surfaces and then applying an electric current near and upon the surfaces, generating intense heat. There are many variations of this technique, namely spot welding, seam welding, butt welding, flash welding, projection welding, and upset welding.

Energy Beam Welding:

In this method a focused high-energy beam (Laser beam or electron beam) is used to melt the workpieces and thus join them together.Solid-State Welding: In contrast to other welding methods, solid-state welding processes do not involve the melting of the materials being joined. Common types of solid-state welding include; ultrasonic welding, explosion welding, electromagnetic pulse welding, roll welding, friction welding (including friction-stir￾welding), etc.

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