Cast Metal & Diecasting Times July/ August 2016 April/May 2016 | Page 13

FURNACES | 11

w w w. n e w b u s i n e s s m e d i a . c o

Customisable holding induction
furnace solution
Milan-based FOMET srl has specialised in the design and construction of induction furnaces since 1963. Described here is
the company’s Duplex channel induction design, which is intended for receiving, holding and super-heating cast iron.

This 40 tons, 425kW FOMET Duplex furnace feeds directly from a cupola, while pouring into a ladle.

Blackouts and the high cost of electricity
sometimes suggest melting with gas or
carbon coke, before feeding a Duplex
channel induction holding furnace. This
technology delivers base iron molten
metal recovery, providing a buffer between
melting and pouring bottlenecks. It is
PLC automated, balanced, controlled
and monitored and requires lower energy
consumption, where a small generator can
hold the temperature. Furthermore, it is
customisable.
These furnaces are particularly suitable
for holding and super-heating cast iron
to produce quality alloys with maximum
metallurgical control for pouring at the
desired temperature. Consistent foundry
operation is assured, regardless of the
level of mechanisation and automation
employed, since it forms a buffer between
the melting and casting sections. It thus
copes with the possibility of breakdowns,
without affecting the quality or the
temperature of the metal.
The great flexibility of the system and its
adaptability to existing installations ensures
that the Duplex receiver furnace respond
to the requirements of the most varied
production programmes. It is adaptable to
any planned hourly production, temperature
variations, accepting various launder
systems, direct feeding from cupolas, rotary
or electric melting, shift work, idle time,
down time etc.
Operating principle
A high voltage electrical source from a
primary coil induces a low voltage, high
current in the metal or secondary magnetic
core. Induction heating is simply a method
of transferring heat energy. Induction
furnaces are ideal for melting and alloying
a wide variety of metals with minimum

melt losses, although little refining of
the metal is possible. There are two main
induction furnace types, namely coreless
and channel.
The channel induction furnace consists
of a refractory-lined steel shell, which
contains the molten metal. Attached to the
steel shell and connected by a throat is an
induction unit, which forms the melting
component of the furnace. The induction
unit comprises a magnetic special iron
core in the form of a ring, around which
a primary induction coil is wound. This
assembly forms a simple transformer in
which the molten metal loop comprises
the secondary component. Heat generated
within the loop causes the metal to
circulate into the main well of the furnace.
The circulation of molten metal effects a
useful stirring action in the melt.
Channel induction furnaces are
commonly used for melting low melting

FOMET Duplex furnace refractory lining.

point alloys and/or as a holding and
superheating unit for higher melting point
alloys such as cast iron. They can be used
as holders for metal melted off peak in
melting, thereby reducing total melting
costs by avoiding peak demand charges.
Easy and quickly interchangeable
flanged inductors can be powered with
an electromechanical switchgear system
or transistor IGBT electronic converter
system. PLC power factor correction and
phase balancing is provided.
The high efficiency of this furnace type
is due to the direct conversion of electrical
energy into heat energy. The air-cooled
and quickly interchangeable inductor
that forms the channel where the metal
passes is flanged on the side or bottom of
the furnace body and the heating of metal
inside the channel occurs through internal