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 it is allowed to cool, solidifying the joint. A filler material is added and sometimes pressure is used to make the welding strong. (Remember the blacksmith joining metals by heating and hammering it together?). There are different types of welding processes that use different energy sources like gas flame, friction, electron beam, laser, electric arc as well as ultra sound. Moreover, there are various jobs in welding that require welding in air, under water welding and even outer space welding.

Types of Welding Processes

Forge Welding
This is the oldest type of welding process 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.

Arc Welding
In arc welding an electric current is used to generate an electric 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 welding rods or electrodes used here which are combustible or non combustible. Often, the 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 (See TIG welding techniques)
• Plasma Arc Welding
• Submerged Arc Welding

Gas Welding
The gas welding process is known as oxyfuel welding or oxyacetylene welding. The reason is that the process employs combustion of acetylene in oxygen to generate the flame used for welding. The flame is around 3100 degree C and hence the cooling process takes a longer time. The type of welding machine used in the gas welding is simple and costs less. The process is generally used to weld pipes and tubes.

Resistance Welding
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 welding process. To develop the resistance in the material, a current of 100-100,000 A is passed through it. The different types of resistance welding are:

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

Energy Beam Welding
The energy beam welding is of two types namely, laser beam welding and electron beam welding. The welding basics of these processes are same and they differ in the energy source used for welding, i.e., laser beam and electron beam. These are fast processes using concentrated energy and having deep weld penetration. The only disadvantage here is that the welding machines used in the process are very costly. The recent developments in energy beam welding are 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 of the jobs in welding are risky and pose dangers to the health of the welders. The dangers 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 by them.

These are the different types of welding processes used to weld materials both in industries and households. As welding 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, don't forget to know about the type of welding being done.