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Presentation on electricInduction furnace by
Stead Fast Engineers Pvt Ltdhttp://www.steadfastengg.com/
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Definition.
Electric induction furnace is type of meltingfurnace that uses electric current to melt the metal.
Once molten, the high frequency magnetic field can
also be used to stir the hot metal, which is useful in
ensuring that alloying additions are fully mixed into
the melt.
Induction furnaces are used in most modern
foundries as a cleaner method of melting metals
than a reverberatory furnace or a cupola.
Sizes ranges from ilogram of capacity to a
hundred tonnes capacity.
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!etals which are melted in an induction furnace
include iron and steel, copper, aluminum, andprecious metals because it is a clean and non"
contact process it can be used in a vacuum or inert
atmosphere.
#acuum furnaces mae use of induction heating for
production of specialty steels and other alloys that
would oxidize if heated in the presence of air.
$he basic principle of induction furnace is theinduction heating.
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Induction heating
Induction heating is a form of non contact heatingfor conductive materials.it is process of heating an
electrically conducting ob%ect by electromagnetic
induction where eddy currents are generated within
the metal and resistant leads to %oule heating of themetal.
&rinciple of induction heating is mainly based on
two well nown physical phenomena.
'. Electro"magnetic Induction(. $he )oule Effect
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Electro-magnetic induction$he energy transfer to the ob%ect to be heated
occurs by means of electromagnetic induction.
*ny electrically conductive material placed in a
variable magnetic field is the site of induced electric
currents, called eddy current which will eventually
lead to %oule heating.
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Joule heating$he %oule heating , also nown as ohmic heating andresistive heating is the process by which the passage
of an electric current through a conductor releases
heat.
$he heat produced is proportional to the square of the
current multiplied by the electrical resistance of the
wire.
+ I-t
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Induction heating relies on the unique
characteristics of radio frequency energy thatportion of the electro magnetic spectrum below
infrared and microwave energy.
Since heat is transferred to the product via
electromagnetic waves the part never comes intodirect contact with any flame the inductor itself does
not get hot and there is no product contamination.
Induction heating is a rapid clean non"polluting
heating. $he induction coil is cool to the touch. $heheat that builds up in the coil is constantly cooled
with circulating water.
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Features of i ductio fur ace
*n electric induction furnace requires an electric coil
to produce the charge. $his heating coil is
eventually replaced
$he crucible in which the metal is placed is made of
stronger materials that can resist the required heat
and the electric coil itself cooled by a water system
so that it does not overheat or melt.
$he advantage of the induction furnace is a clean
energy efficient and well controllable meltingprocess compared to most other means of metal
melting.
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$he induction furnace can ranges in size from a small
furnace used for very precise alloys only about a
ilogram in weight to a much larger furnaces made to
mass produce clean metal for many different
applications.
/oundries use this type of furnace and now also more
iron foundries are replacing cupolas with induction
furnaces to melt cast iron as the former emit lots of
dust and other pollutants.
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Construction of induction furnace. $here are many different design for the electric
induction furnace but they are center aroundbasic idea.
$he electrical coil is placed around or inside of
crucible, which holds the metal to be melted often
this crucible is divided into two different parts. $he lower section holds the melt in its purest form
,the metal as the manufacturers desire it , while
the higher section is used to remove the slag, the
contaminants that rise to the surface of the melt. 0rucibles may also be equipped with strong lids to
lessen how much air has access to the melting
metal until it is poured out maing a purer melt.
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Fig:
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Types of induction furnace$here are two main types of induction furnace, corelessand channel.
'"0oreless induction furnace, $he heart of the coreless induction furnace is the coil, which
consists of a hollow section of heavy duty, high conductivitycopper tubing which is wound into a helical coil.
0oil shape is contained within a steel shell.
$o protect it from over heating the coil is water cooled, the
water being recirculated and cooled in a cooling tower.
$he crucible is formed by ramming a granular refrectorybetween the coil and a hollow internal.
$he coreless induction furnace is commonly used to melt all
grades of steels and irons as well as many non"ferrous
alloys.
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("0hannel Induction /urnace$he channel induction furnace consists of a refrectory
lined steel shell which contains the molten
metal.*ttached to the steel shell and connected by a
throat is an induction unit which forms the meltingcomponent of the furnace.
$he induction unit consists of an iron core in the form of a
ring around which a primary induction coil is wound.
$his assembly forms a simple transformer in which themolten metal loops comprises the secondary
components. $he heat generated within the loop causes
the metal to circulate into the main well of the furnace.
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$he circulation of the molten metal effects a useful
stirring action in the melt.0hannel induction furnaces are commonly used for
melting low melting point alloys and or as a holding
and superheating unit for higher melting point alloys
such as cast iron.
AdvantagesHigher Yield. $he absence of combustion sources
reduces oxidation losses that can be significant in
production economics.Faster Startup. /ull power from power supply is
available instantaneously1 thus reducing the time to
reach woring temperature.
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Flexibility.2o molten metal is necessary to start
medium frequency coreless induction melting
equipment.Natural Stirring. !edium frequency units can give a
strong stirring action resulting in a homogeneous
melt.
Cleaner elting. 2o bi"product are produced due tocleaner melting environment.
Co!pact "nstallation. 3igh malting rates can be
obtained from small furnaces.
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#nergy Conservation. Overall energy efficiency in
induction melting ranges from 44 to 54 percent, and is
significantly better than combustion processes.
Disadvantages$he one ma%or drawbac to induction furnace usage
in a foundry is the lac of refining capacity1 charge
materials must be clean of oxidation products and of
nown composition, and some alloying elements may
be lost due to oxidation.
emoval of S 6 & is limited, so selection of chargeswith less impurity is required.