Classification of welding process based on method of welding

 In general, various welding processes are classified as follows:

1. Gas welding:

(a) Air-acetylene welding

(b) Oxy-acetylene welding

(c) Oxy-hydrogen welding.

2. Arc welding:

(a) Carbon arc welding

(b) Plasma arc welding

(c) Shield metal arc welding

(d) Tungsten Inert Gas (TIG) welding

(e) Metal Inert Gas (MIG) welding

(f) Submerged arc welding

(g) Electro-slag welding.

3. Resistance welding:

(a) Spot welding

(b) Seam welding

(c) Projection welding

(d) Resistance butt welding

(e) Flash butt welding

(f) Percussion welding.

4. Solid state welding:

(a) Cold welding

(b) Diffusion welding 

(c) Forge welding

(d) Explosive welding

(e) Friction welding

(f) Ultrasonic welding 

(g) Hot pressure welding

(h) Roll welding.

5. Thermo chemical welding:

(a) Thermit welding 

(b) Atomic welding.

6. Radiant energy welding:

(a) Electric Beam welding

(b) Laser Beam welding.

There are two main types of welding process which are classified according to the source of energy employed for heating the metals and the state of metal at the place being welded.

1. Fusion welding

2. Pressure or plastic welding.

1. Fusion Welding

In fusion welding, the metal at the joint is heated to a molten state and then it is allowed to solidify. When heat alone is used during welding, the process is called fusion welding. Pressure is not applied during the welding process and hence, it is also called non-pressure welding. Filler material may be required during this type of welding.

Examples: Gas welding, arc welding and electron beam welding.

2. Plastic Welding

In pressure or plastic welding, the metal parts are heated to a plastic state and they are pressed together to make the joint. Hence, it is known as pressure welding. Here, there is no filler materials required.

Examples: Resistance welding, pressure welding and forge welding.