Author: haroonkhan

It is simplest form of resistance welding. In this process, a pair of water-cooled copper electrodes is used. Two overlapping metal plates are held between these electrodes’ jaws as shown in Figure 20.42. Figure 20.42 Resistance Spot Welding The pressure is applied to a very small area, which is known as spot. The resistance at the inner…

In a resistance welding, heat is generated by passing electric current through high resistance. The amount of heat generated depends on the value of current and resistance as shown in the formula.   H = I2 · R · t Joul   where I = Current in ampere, R = Resistance in ohm, and t = Time in second. When the electric current is passed through…

A highly ionized gas is known as plasma. In a plasma arc welding, arc is created between a non-consumable tungsten electrode and workpiece. A water-cooled copper nozzle surrounds tungsten electrode, which is used as cathode as shown in Figure 20.41. A gas (inert gas) like argon is supplied surrounding the tungsten electrode. The gas is forced…

In this welding, arc is created between two non-consumable electrodes (as shown in Figure 20.40) by supplying AC current. When hydrogen gas is passed through the arc, the heat of arc is absorbed by hydrogen molecules and dissociate into hydrogen atoms. When hydrogen atoms reach at cold work surface recombines to form hydrogen molecules with releasing…

Electroslag welding is used for welding of thick metal plates. Two plates are kept vertical at a distance of 2–3 cm. The filler wires and flux are kept in this gap. Here, the filler wires are used as the electrodes. The current supplied is AC. Initially an arc is created which melts the flux, and…

This welding process is very similar to MIG welding except that a blanket of granular, fusible flux shields the metal arc during the welding operation instead of inert gas. A bare electrode is fed through the welding head into the flux as shown in Figure 20.38. The arc is started either by striking the electrode on…

In this welding process, a non-consumable electrode of tungsten is used as shown in Figure 20.37. Filler material is supplied externally if it is required. The tungsten electrode is connected at negative pole of power supply and work at positive pole of power supply. Inert gas like argon or helium is supplied through a gas nozzle…

In MIG welding, a high current density is supplied to the electrode and workpiece. Carbon dioxide gas or any inert gas like helium or argon is supplied to protect the weld pool. The electrode used is consumable and is in the form of wire. Automated feed of the wire is used as shown in Figure 20.36.…

In this welding process, a special electrode that consists of metal wire which has bonded coating containing flux of desired gradients is used. The heat required for welding is generated by an arc between the flux covered consumable electrode and the workpiece. The process is shown in Figure 20.35. As the coating on the electrode melts…