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download sealed quench furnace pdf

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KANTHAL
SUPER
CASE
HISTORIES
Retrofitted Sealed Quench
-The fastest and most
reliable furnace
Tamebridge Heat Treatments based
in the West Midlands, England, is a
rapidly growing company supplying
sub-contract heat treatment to a
range of engineering based
industries in areas covering
Automotive,
Electronic,
Construction, Domestic and
Household products.
The company’s aim is simple - to
supply the best possible quality,
service and expertise to their customers. For this to be achieved,
Tamebridge need their heat treatment
furnaces to be consistent in
performance in terms of productivity, efficiency and reliability.
too quickly.
The company realised that they could
not continue operating this furnace in
such an inefficient way and decided that
something had to be done to improve the
productivity.
The initial thoughts were to convert
to gas heating. However, at this time
Tamebridge heard about an electric heating system that claimed to provide an
PROBLEMS WITH A
SLOW FURNACE
An electrically heated Sealed
Quench furnace did not live up to
these demands. The furnace was an
Ipsen T-5 of the old design, equipped
with metallic elements fitted inside
ceramic radiant tubes.
Due to the low power of the furnace, it was slow to recover back to
the process temperature when recharging batch to batch. The lifetime
of the elements was unreliable as was
the lifetime of the ceramic tubes,
which tended to crack due to thermal
shock if the furnace was heated up
The 90 kW Kanthal Super heated furnace at Tamebridge Heat Treatments Ltd.
equivalent heating rate performance to
gas, but without the maintenance costs
and problems.
RETROFITTED WITH
KANTHAL SUPER
This electric heating system incorporates KANTHAL SUPER U-shaped elements (based on
MoSi 2 ) which are easily installed
vertically through the previous radiant
tube holes in the roof. The elements
operate directly in the protective furnace
atmosphere, without protection tubes.
Following discussions with Kanthal
Ltd and RJT Furnaces, the decision was
made to convert the furnace to
KANTHAL SUPER.
The furnace was fitted with 8
KANTHAL SUPER 9/18 1700 elements, each rated at maximum 11.25 kW,
giving a total furnace power of 90 kW.
The power to the furnace is automatically regulated by a 3 phase thyristor
unit firing into the primary side of the
Scott transformer to which the element
system is connected. The thyristor unit
is governed by a PID temperature controller.
Some problems were experienced
with the control equipment initially, but
since corrected the furnace has proven
to be extremely reliable.
After 18 months of operation two
elements were exchanged, which corresponds to the normal average lifetime of
between 4 to 6 years.
IMPROVED THROUGHPUT
BY 100 %
To a heat treatment company, the
throughput capability of a furnace is the
major factor which limits how much
work can be processed. Since converting
this furnace, the recovery rate with a
typical charge weight of 500 kg is 45 50 mins, compared with the 21/2 to 3
hours needed previously. A heating rate
increase of between 300 and 400%! In
effect, the furnace has provided an
increase in processing capacity of more
than 100%.