Here is an essay on ‘Resistance Welding’ for class 11 and 12. Find paragraphs, long and short essays on ‘Resistance Welding’ especially written for college students.
Essay on Resistance Welding
Essay Contents:
- Essay on the Meaning and Principle of Resistance Welding
- Essay on the Electrodes for Resistance Welding
- Essay on the Power Supply for Resistance Welding
- Essay on the Applications of Resistance Welding
- Essay on the Advantages of Resistance Welding
- Essay on the Disadvantages of Resistance Welding
Essay # 1. Meaning and Principle of Resistance Welding:
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Resistance welding is a group of welding processes in which welding heat is obtained from resistance of the work to the flow of electric current and by the application of pressure. No filler metal or flux is added.
In resistance welding a heavy current above 100 A at a low voltage (typically 1 volt) is passed directly through the joint for a very short time. This high amperage heats the joint.
The heat developed by the resistance to flow of current in resistance welding can be expressed as:
H = I2 Rt
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where, H = Total heat generated in the work in joule.
I = Electric current in Amps
t = Time for which the electric current is passing through the joint in sec.
R = Resistance of the joint
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Alternating current is formed to be most suitable for resistance welding as it can provide any desired combination of current and voltage by means of suitable transformer.
In order to obtain a good weld and avoid overheating it is necessary to maintain the contact resistance uniform which depends upon the surface conditions. The pressure necessary to affect the weld, varies for 2.5 – 5.5 Kgf/mm2.
The electrical voltage required ranges from 2 to 10 volts depending upon the composition, area, thickness etc. of metal plates to be welded.
Essay # 2. Electrodes for Resistance Welding:
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Since the electrodes in resistance welding have to carry large amount of current, pressure and also help to remove the heat from the weld zone thus preventing overheating and surface fusion of work so electrodes should have higher electrical conductivity as well as higher hardness. Hence copper in alloyed form is used for making electrodes.
Essay # 3. Power Supply for Resistance Welding:
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In resistance welding ac. supply is used because of ease and convenience. The supply generally required is low voltage at high current which can be obtained from transformer ranges from a few KVA to as much as 1MVA. The power factor will be about 0.25.
The power factor can be improved by connecting capacitors of suitable capacity in parallel with the welding transformer.
Essay # 4. Applications of Resistance Welding:
(i) Making metal furniture.
(ii) Making containers of different equipments.
(iii) Joining sheets, bars and tubes.
(iv) Making fuel tanks of tractors and cars etc.
(v) Welding automobile parts and aircraft.
Essay # 5. Advantages of Resistance Welding:
1. No filler rod and flux is needed.
2. It can produced large production of work at high speeds.
3. Little skill is required to operate the resistance welding machine.
4. Resistance welds are made very quickly.
5. Resistance welding operations are automatic.
6. It is possible to weld dissimilar metals as well as metal plates of different thickness.
7. No consumables are used in this process except the electrical power; hence it is a very economical process.
Essay # 6. Disadvantages of Resistance Welding:
(i) The initial cost of equipment required is high.
(ii) Skilled persons are required for maintenance.
(iii) Bigger job thicknesses cannot be welded.
(iv) In some materials, special surface preparation is required.
(v) Certain resistance welding operations are limited only to lap joints.