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Write short notes on Induction heating:

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Induction heating processes make use of currents induced by electromagnetic action
in the material to be heated. Induction heating is based on the principle of
transformers, there is primary winding through which ac current is passed. The coil is
magnetically coupled with the metal to be heated. An electric current is induced in
this metal when the ac current is passed through the primary coil.
Applications:
• Surface hardening
• Deep hardening
• Tempering
• Soldering
• Melting
• Smelting etc.
(iv) Electrical welding
Welding is the process of joining metals of similar composition by heating to suitable
temperature with or without application of pressure and addition of filter material.
The result of welding is a continuity of the homogeneous material and is of the same
composition and characteristics as the parts, which are joined together.
Welding process may be classified as :
(i) Pressure welding: The process in which the metal parts to be joined are heated
to a plastic stage and then joined by applying external forces are known as plastic or
pressure welding.
(ii) Fusion welding: The process in which the metal parts to be joined are heated
to molten state and then allowed to solidify joining a localized homogeneous union of
the two is known as fusion welding.
Welding process may be further classified as:
a. Electric resistance welding: Electric resistance welding is most
commonly used kind of pressure welding. It can be applied to almost any metals with
in certain limits of composition.
Principle of Electric Resistance Welding:
This process makes use of the heat generated by a heavy electric current passing
through the materials being joined. The electric resistance between the surface in
contact being mainly responsible for the rise in temperature. The heat generated bring
these surfaces to the plastic state, at this point mechanical pressure is applied to
squeeze the material together thus forming the joint.
Arc Welding: An electric arc is produced by bringing two conductors connected to a
suitable source of electric current, firstly in contact and then separately by a small
distance. The current continues to flow across the small gap and gives intense heat.
The heat developed is utilized to melt the part of the work piece and the filter metal
and thus form the joint. So the welded joint is the union of metal parts made by
localized heat without any pressure.
Principle of Arc Welding:
Current from a source (ac or dc) is obtained. One terminal is connected to the
electrode and to other to the work piece and the circuit is completed through air gap.
The gap is provided between the tip of the electrode and the surface of the work piece
by keeping the electrode at a distance of about 3mm to 6 mm from the surface of the
work piece. Due to the interruption by the air gap or gas, heat is produced and the
temperature attained varies from 3700o
to 4000oC

gregorymasila answered the question on February 20, 2018 at 16:14

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Write short notes on Induction heating:

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