Importance Of Welding

CHAPTER 1 INTRODUCTION

Welding is characterized as a coalescence of metals produced by heating to a suitable temperature with or without the utilization of pressure, and with or without the utilization of a filler material. The procedure of welding discovers application in assembling vehicles, aeroplanes, rail mentors, machine segments, metal structures, boilers and boats.

1.1 Methods of welding

There are two methods by which welding is performed

1.Plastic welding.

2.Fusion welding.

1.1.1 Plastic welding

In this technique, the metal parts are heated to a plastic state. At this stage, pressure is connected to make a flawless joint. It is otherwise called pressure welding.

1.1.2

1.3.3 Resistance Spot welding:

• Resistance welding, specifically, resistance spot welding and resistance seam welding are generally used to join thin metals and can be utilized on thin foils.

• The weld capacity comprises of three components: resistivity, heat conductivity and melting temperature. Metals with high resistance, low thermal conductivity and low melting point have high weld capacity.

• All steels furthermore titanium have these properties. Aluminium and magnesium are more hard to weld since they don 't have these properties.

• Hence in automotive industries resistance spot welding is widely used for welding steel.

1.4 COLD METAL TRANSFER WELDING:

• CMT is a digital controlled short circuit welding process which allows the material transfer to take place after arcing period, during which the filler material is moved towards the weld pool.

• When the filler metal dips into the weld pool, the arc is extinguished, and the welding current is lowered.

• Then the wire has a rearward movement on short circuit, during which the droplet gets detached from the filler.

• The main advantage of CMT welding is the short circuit current is kept