Induction heating uses an alternating magnetic field generated by an induction coil to heat electrically conductive materials. The magnetic field induces eddy currents in the material, which generate heat inside the material. Induction heating has several advantages over other heating methods, including contactless heating, selective heating of parts, fast start-up and heating times, and no pollution of the surrounding area. The system consists of a power supply, induction coil, and water cooling unit. Common applications include melting, heat treatment, welding, and forging.

1. Induction Heating
BY-
Anuj A. Umare

2. WHAT IS INDUCTION HEATING?
• Induction Heating is a Contactless Heating Method of bodies, which
absorb energy from an Alternating Magnetic Field, generated by
Induction Coil (Inductor).
OR
• heating of material by means of an electric current that is caused to
flow through the material or its container by electromagnetic
induction.

3. Principles of Induction Heating :-
Chain of phenomena:-
1.Power supply delivers current (I1) to induction coil.
2.Coil currents (ampere-turns) generate magnetic field.
Lines of field are always closed and each line goes
around the current source – coil turns and work piece.
3.Alternating magnetic field flowing through the part
cross-section (coupled to the part) induces voltage in the
part.
4. Induced voltage creates eddy currents (I2) in the part
flowing in direction opposite to the coil current where
possible.
5.Eddy currents generate heat in the part.
Magnetic
Flux lines
Power
Supplying
Circuitry

4. Specific Features of Induction Heating:-
• Heating is contactless.
• Heat generation occurs inside the part.
• Method can provide very high power densities.
• Heating may be highly selective in the depth and along the surface.
• Any processing atmosphere (air, vacuum).
• Very high temperature may be created.
• Stand-by losses of equipment are very low.
• Fast start-up.
• Heating may be easily programmed and automated.
• No pollution of surrounding space.
• Compare to safe gas heating.

5. Design(Temporary):-
job
heating
plat
Structure
Electronic
& Digital Display
Base

6. Parts of an Induction Heating
System:-
An induction heating system
comprises a tank circuit, a power
supply, and a work coil. In industrial
applications, there is sufficient
current passing via the coil to need
water cooling; therefore a basic
installation contains a water cooling
unit. The alternating current from
the AC line is converted through a
power supply to an alternating
current that is in line with the
combination of coil inductance,
work head capacitance, and
component resistivity.

7. There are two mechanisms of energy absorption:-Eddy Current &
Hysteresis
• Eddy current heating occurs in all conductive materials (magnetic or non-
magnetic steels, copper, aluminum, graphite, molten glass or oxide etc.) when
they are placed in an alternating magnetic field. Eddy currents always flow in a
closed loop and for effective heating there must be a good path for current to flow
in the part to be heated. For example, it is easy to heat a wire loop but almost
impossible to heat a thin wire then the loop is open.
• Hysteresis heating is zero in non-magnetic materials (aluminum, copper, hot
steels) or responsible for a small percentage of heat generation in compact
magnetic bodies (mainly steels at low or middle temperatures). However, in
magnetic materials composed of particulates (including magnetic flux
concentrators) hysteresis may be the major source of heat generation. Each
particle is heated individually and the workpiece may have any shape and size
(massive bodies, strips, films, wires).

8. Operating Frequency:-
EX-a 20mm steel bar can be stress-relieved by heating it to 540°C (1000°F) using a 3kHz
induction system. However, a 10 kHz system will be needed to harden the same bar by heating it
to 870°C (1600°F). Hence it can be said that higher operating frequencies, mostly more than 50kHz,
can be used to heat smaller parts with induction and lower operating frequencies can be used to heat
larger parts more efficiently.
In the case of advanced solid-state induction power supplies with embedded microprocessor control
systems, consistent and effective heating techniques are achievable based on the fact that all parts are
placed at a consistent location within the coil.
Approximate smallest diameter for efficient heating at different
induction frequencies
Material Temperature 1 kHz 3 kHz 10 kHz 30 kHz
Steel below
curie
540 °C
(1000 °F)
8.89 mm
(0.35 in)
5.08 mm
(0.20 in)
2.79 mm
(0.11 in)
1.27 mm
(0.05 in)
Steel above
curie
870 °C
(1600 °F)
68.58 mm
(2.7 in)
38.10 mm
(1.5 in)
21.59 mm
(0.85 in)
9.65 mm
(0.38 in)

9. Advantages of Induction Heating:-
• Short heating cycles and high production rates.
• Better metallurgical results due to fast and clean heating.
• Energy savings due to selectivity and high efficiency.
• Good control and repeatability.
• Minimal or no surface oxidation and decarburization.
• Lower distortions.
• Favorable for industrial environment (in-line heating, no pollution, “push button” performance).
• Some processes may not be accomplished other than by induction.
• Safer surrounding environment.

10. Major Applications of Induction Heating:-
• Melting
• Forging & Forming
• Heat Treatment
• Welding
• Brazing & Soldering
• Shrink-fitting
• Bonding
• Inductively Coupled Plasma
• Crystal Growth

11. THANK YOU