Welding:-
Welding is the process of joining similar or different metal by heating.
Welding can be done with or without the application of pressure and addition of filler material.
During welding the edges of metal pieces are either melted or brought to plastic stage.Welding gives a permanent joint.
Welding is used in fabrication of automobile bodies,aircraft,machine frames,boilers,ship building,railway wagons etc
Types of welding:-
1.ARC welding
Metal arc
Metal Inert gas
Tungsten Inert gas
Plasma arc
Induction
Electro slag
Submerged arc
2.Resistance Welding
Spot
Butt
Seam
3.Solid state Welding
Friction
Ultrasonic
4.Modern Welding
Electron Beam
Laser Beam
5.Gas Welding
Oxyacetylene
6.Thermit Welding
Welding equipment
The most commonly used arc welding equipments are
Power Source (AC or DC)
Welding Cable
Electrode holder
Protective shield
Apron and Gloves
Chipping hammer
Wire brush
Earthing clamps
Electrode
1.Power Source (AC or DC)
Both AC and DC equipment are employed in arc Welding. D.C arc Welding Machines are D.C generators driven by an electric motor. A.C Welding Machines are transformers stepping down the main supply voltage and current suitable for arc Welding
A power supply is used to generate the arc, which can either use an alternating current (AC) or a direct current (DC). The choice of power source (AC or DC) decides the polarity of the electrical current that runs through the electrode. The power source used also impacts the weld produced.
2.Welding cable
These are used to connect the electrode holder and the ground clamp to the power source.The cable consists of many fine copper or aluminium wires standard together and enclosed in a flexible insulating jacket
3.Electrode holder
Electrode holder is a device used for mechanically holding the electrode and for conducting the current to it
4.Protective shield
The protective shield or face shield may be hand held or it may be a head helmet with either a solid lens or a flip front.It allows maximum eye protection from hot slag while chipping.
5.Apron and Gloves
Apron is used to protect the body.It should be made of leather.Hand gloves are used to protect the hands from electric shock,arc radiation,heat and hot spatters.The gloves should be made up of leather.
6.Chipping hammer
A chipping hammer is chisel shaped and is pointed on one end to aid in the removal of slag.
7.Wire brush
A wire brush is used to clean the surface 0f base metal of rust,oil,scale,paint,etc.
8.Earthing clamps
Earthing clamps complete the circuit between the electrode and Welding machine is generally fastened to metal being welded either with a clamp or some other means