Page 35 - CITS - Welder - Trade Theory

WELDER - CITS

2 Basic electricity applicable to arc welding.
Use the external power to motor /chemical than generate the electricity. this external power generate to
electromotive force (E.M.F )

In the welding process, the electrical energy is converting to heat energy. Used the electrical current melt the
metal / heat them to red hot condition. So electrical is used to very large extent in many welding process.
Created a high temperature (3400°C- 4000C°) between electrode and work using the electric voltage and high
current (All types of arc welding) All the resistance welding-Like spot welding, seam welding, friction welding.
Electron beam welding &Electro slag welding.

Heat and temperature and its terms related to welding

Objectives: At the end of this lesson you shall be able to
• differentiate between heat and temperature
• state the units of heat and temperature measurement
• differentiate between heat and temperature as applicable to welding
• convert centigrade to Fahrenheit.

Introduction to heat
1 Heat– Heat is a type of energy. Due to which we experience heat and cold. It is absorbed by molecular .any
heat to object speed of the speed of the molecules increases. Object heat is cool down than molecules also
decreases.
Units of heat
a Calories– Calories is the unit of heat in matric system/C.G.S System. The amount of heat required to raise
the temperature of one gram of water is called a calories.

b British Thermal Unit –The unit of heat in the British system (F.P.S system) is the British Thermal Unit. The
amount of heat used to Increase the temperature of pound water by one degree Fahrenheit is called British
Thermal Unit. (B.Th.U). British Thermal Unit = 252 Calories.

c Centigrade Heat Unit – The amount of heat used to increase the temperature of a pound water by one
degree of calcium (Centigrade) is call C.H.U.

22

CITS : C G & M - Welder - Lesson 6&7 CITS : C G & M - Welder - Lesson 6&7