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Low-Frequency Technology from eldec:
Induction Heating with Shorter
Cycle Times and Improved
Process Reliability- EMAG
F
aster, more precise, improved efficiency—these
qualities are why induction heating has conquered
many areas of application. The process reveals its well-
known strengths, such as easy process integration, improved
productivity and low energy consumption, for example, in
heating processes applied prior to welding and joining, in
the hardening of bonding agents or in pre-heating when
infusing with resin. The experts at EMAG eldec know these
advantages inside out: For more than 30 years, this company
has been developing high-quality and robust generators for
induction heating. The specialists are currently expanding
Mr. Dirk Schlesselmann
Deputy Head of Application Technology
Research and Development at eldec
Temperaturverlauf_1_de & Temperaturverlauf_2_de
Werkstueck-Induktor_1_de & Werkstueck-Induktor_2_de
Two temperature distributions—each one after a processing
time of five seconds. When using 2 kHz (left image), the
desired temperature of 200 degrees Celsius appears within
the corona—red means: target temperature reached. The
authorized maximum temperature of 370 degrees Celsius
is not exceeded. When using 12.5 kHz (right image), the
maximum temperature must be increased to 420 degrees—
gray means: maximum temperature exceeded.
A typical application for the induction technology from eldec: The
corona must be heated to a temperature of at least 200 but no more
than 370 degrees Celsius.
their portfolio withlow-frequency technology (LF). Concrete
application examples make this very clear: The entire process
benefits from shorter cycle times and higher reproducibility.
Welding and joining processes are particularly challenging
for automotive production, since mass quantities needto
be machined, with short cycle times and without any
unacceptable changes to the material structure - this is
why induction heating often is an crucial component of the
complete process. This technology helps to quickly bring the
component up to the temperature required for processing.
However during the heating, the component must not
be overheated, as this would result in a loss of hardness,
oxidation or unacceptable deformation.
LF Technology Wins in Trials
The advantages that EMAG eldec LF generators (low
frequency) provide in this context are illustrated by a current
46 | january-february 2019 |
application example from the eldec technology center: The
goal here was to heat up a simple corona (similar to a gear)
to a temperature of at least 200 and no more than 370
degrees Celsius—all while maintaining the shortest possible
cycle time and highest process reliability. To achieve this,
the experts used a numerical calculation to comparatively
analyze the induction heating with a low frequency, as well
as with a typical medium frequency. The results were clear:
• When using a low frequency of 2 kHz and a process time
of five seconds, the desired heating pattern of at least
200 degrees Celsius appears throughout the corona (see
Figure).
• If a medium frequency of 12.5 kHz is used, the admissible
maximum temperature must be increased to 420 degrees
Celsius. Otherwise, the minimum temperature of 200
degrees will not be achieved throughout the corona within
the targeted five seconds. However, the higher maximum
temperature is not admissible.
• As an alternative, the process time can also be increased
when medium frequencies are used. This will require
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