What is Flash Welding? – Parts, Process, Advantages, Disadvantages and Applications

Flash Welding

Flash welding, also called flash butt welding, is a resistance welding process, in which the ends of the workpieces are pressed together and a heavy electric current is passed through the joint during the welding process.

In flash welding, the electrical current is applied to the workpieces before they are brought together so that when they meet arcing (or flashing) takes place.

Parts of Flash Welding

The main parts of the flash welding process are described below −

  • Power Supply – An AC power supply is used to provide power for the flash welding or flash butt welding.

  • Welding Transformer – A welding transformer is used for changing the current and voltage for the welding process.

  • Clamps – In flash welding process, two clamps are used viz. stationary clamp and movable clamp. The stationary clamp remains in a fixed position while the movable clamp moves about its axis. The metal workpieces are hold by these clamps.

Process of Flash Welding

The schematic diagram of the flash welding process is shown in the figure.

  • In flash welding process, the two workpieces to be welded are clamped strongly in a flash welding machine.

  • The two workpieces are brought together, and the flash created and the resistance to the current flow heat the contacting surfaces.

  • As soon as the workpieces have been brought to their melting temperature, the supply of current is cut off and the workpieces are rapidly brought together under high mechanical pressure which forces the fused metal and slag out of the joint and making a good solid weld.

  • When the ends of the workpieces collide, the squeezed molten metal flashes out in the outward direction, and this outward direction of the metal causes a flashing effect. Due to this flashing effect, this welding process is called as flash welding.

Advantages of Flash Welding

Following are the main advantages of the flash butt welding process −

  • In flash welding, the power consumed is less as the arc is also produces some heat required for welding process.

  • Flash welding is very cheap.

  • Flash welding can be used for welding metals having different melting temperatures.

  • Flash welding produces neat, clean and strong welds.

Disadvantages of Flash Welding

Following are some of the disadvantages of flash welding −

  • The welding machine used for flash welding is bulky.

  • Chance of fire hazards is high.

  • In flash welding, metal is lost during flashing.

Applications of Flash Welding

Some applications of the flash welding are given as follows −

  • Flash welding is used extensively in production work, particularly in welding rods and pipes together.

  • Flash welding is widely used in automobile construction on the body, axis, wheels, frames and other parts.

  • Flash welding is also used in welding motor frames, transformer tanks and many other types of steel containers.