SAMPE Journal - November/December 2021 - 22

FEATURE / THICK ORGANO-SHEET
Figure 3. Developed induction heating (IH) units: a) for heating carbon fiber materials directly with
double Teflon belts, b) for heating steel belts before press zones in double belt press.
of composite. In order to overcome the problem
for heat transfer efficiency, we have developed
novel induction heating units for carbon fiber
reinforcements. This heating system was applied
for increasing the material temperature before
being pulled into double belt press. Recorded
temperature profiles, impregnation quality and
mechanical property of the composite laminates
are presented here.
EXPERIMENTATION
Materials
In this study we used carbon fiber plain woven fabric
(T700SC-12K, 210 g/m2
woven fabric, NCF, and non-woven can be heated,
but unidirectional fiber cannot be heated. The
great advantage is that each carbon fiber layer can
be heated directly (even if resin films are contained
between carbon fiber layers) and the heat does not
transfer through thickness direction like an electric
heater or hot air furnace. The other one is for
heating steel belts, which is integrated into double
belt press before press zones, as shown in Figure 3b.
The heating ability is much higher than that by hot
air blow in press zones. These heating processes are
illustrated in Figure 4 with conventional thermal
conduction heating for comparison.
, Toray) for reinforcements
and polyamide (PA) 6 films (CM1006, 0.1 mm and
0.05 mm thick, Toray) for matrix resin. The sample
size was 550 mm width x 3 m length. The carbon
fiber woven fabrics were heated at 240°C for 8 hours
to remove sizing agent on the surface of carbon
fiber before experiment. This effect is to improve
interface property with PA6 resin and to prevent
volatile fragments from pyrolyzed sizing agent at
the molding temperature during double belt press
process. 28 layers of fabrics and 29 layers of resin
films were stacked alternately with an ultimate
fiber volume fraction of 53%, and corresponding
thickness of about 6 mm.
Induction Heating Unit
Two type of induction heating units have been
developed in this study. The one is for heating the
stack of carbon fiber materials directly with running
double Teflon belts. The unit is placed in front of
double belt press machine, as shown in Figure 3a.
IH coil units are installed in parallel with Teflon
belts, heating carbon fiber materials continuously.
Carbon
fibers are conductive,
creating eddy
currents in closed loops within carbon fiber layer,
which raise the temperature by Joule heating. Thus,
22 | SAMPE JOURNAL | NOVEMBER/DECEMBER 2021
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Double Belt Press Experiments
Composite samples were fabricated with a double
belt press. The one was fabricated with standard
process as depicted in Figure 1 at a process velocity
of 0.2 m/min. The other one was fabricated with
Figure 4. Two types of induction heating process: a) heating carbon fiber
directly, b) heating steel belt, c) standard thermal conduction heating for
comparison, d) details of induction heating mechanism.

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SAMPE Journal - November/December 2021

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