Types of Welding

Welding is a process through which metals and thermoplastics are joined together. In the process, the material to be joined is heated to the point that it melts and then is allowed to cool, solidifying the joint. A filler material is added and sometimes pressure is used to make the weld strong.

There are different types of welding processes that use different energy sources, like gas flame, friction, electron beam, laser, electric arc, as well as ultrasound. Moreover, there are various jobs that require welding to be done in the air, underwater, and even in space.

This is the oldest type wherein the metals are heated and then hammered together to form the weld. This was used by blacksmiths to join both similar and different metals. Here the metals do not melt completely, and no filler material is needed to join the metals.

In this method electric current is used to generate an arc between electrodes. This arc is used to heat the metal for welding. The current can either be direct or alternating. There are two types of rods or electrodes used in this method: combustible or non-combustible.

Often, arc welding takes place in an inert gas environment, and a filler is used to produce the weld. The different types of arc welding are:

• Shielded Metal Arc Welding
• Electroslag Welding

• Fluxed Core Arc Welding
• Gas Metal Arc Welding
• Gas Tungsten Arc or Tungsten Inert Gas Welding
• Plasma Arc Welding
• Submerged Arc Welding

Gas welding is also known as oxyfuel or oxyacetylene welding as the process employs combustion of acetylene in oxygen to generate the flame used. The flame is around 3,100 °C, and hence, the cooling process takes a longer time. The type of machine used is simple and costs less. The process is generally used to weld pipes and tubes.

The process involves passing electric current through the material. The weld is formed by using the electrical resistance of the material along with force and time used to keep the material together during the process. To develop resistance in the material, a current of 100-100,000 A is passed through it.

The different types are:

• Spot Welding
• Seam Welding
• Flash Welding
• Resistance Projection Welding
• Upset Welding

Energy beam welding is of two types: laser beam and electron beam. The welding basics of these processes are same and they differ only in the energy source used. These are fast processes using concentrated energy and having deep weld penetration. 

The only disadvantage is that the machines used in the process are very costly. Recent developments in energy beam welding include x-ray welding and laser hybrid welding.

Some other welding methods are:

• Ultrasonic Welding
• Friction Welding
• Diffusion Welding
• Induction Welding
• Cold Welding
• Exothermic Welding
• High Frequency Welding

Most jobs in welding are risky and pose dangers to the health of the welders. These include exposure to heat, fine particles, current, oxides and toxic fumes. Hence, precautions should be taken to prevent any fatalities. Protective gloves, jackets, welding helmets, and goggles must always be used.

As technology develops, there will be introduction of more sophisticated equipment in this field. Next time when you watch a welding process being carried out in a factory, try and identify the type of welding being done.