JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 49

process

Reduction of cure cycle time through
microwave curing: a vision for the near future

By
Dipl.-ing. (FH) Daniel TeuFl
Dr. monT. elisabeTH laDsTäTTer
proF. Dr. Klaus DrecHsler
insTiTuTe For carbon composiTes
TecHniscHe universiTäT müncHen

T

(for ε''<ε' with an error up to 10%) (1)

In general, the penetration depth Dp is
defined as the range into the material at
which the power density lessens to 1/e
of the surface value. The power density
is proportional to the quadrature of the
inner electric field strength Ei. The real
part of the complex permittivity ε' and
the loss factor of the dielectric ε'' are
material properties. They vary according
to material temperature and microwave
frequency. λ0 is the wavelength of the
electromagnetic wave in a vacuum environment.

system. In more detail, the amount of
energy generated inside the material, p,
can be described by the dielectric heating equation:
(2)
where f is the frequency of the electromagnetic field and the resulting inner
electric field strength, Ei, depends on the
orientation of the electric field vector. In
more detail, Ei depends on the impact
angle of the E-field vector and can be
narrowed down by:

The penetration depth, in combination
with the thickness of the material, is an
indicator for the efficiency of a heating

Considering the temperature dependency of ε' and ε'' as well as the two

Fig. 1: Excitement of molecules by an electromagnetic field

Fig. 2: Temperature distribution when heating
with an oven and a microwave applicator

No100 October 2015 / jec

Special JEC Asia 2015

he most important thing to know
about microwave heating is its
mode of operation. Microwaves
are electromagnetic waves that are
reflected by metals and conducting
materials, but penetrate other materials
and may interact with their molecules
(see Figure 1). Therefore, microwave
heating is not the transport of heat into
a material, but rather the conversion of
electromagnetic energy to heat depending on the material's properties [1]. This
results in direct heating of the material,
as depicted in Figure 2.
A good first indicator to estimate how
much energy can be converted into heat
is the penetration depth of microwaves
into a material. This penetration depth
[1] can be described by the following
equation:

Microwave curing has a huge potential to reduce the cycle time of heating processes in composite manufacturing. It also significantly reduces
energy consumption. In theory and in special applications, such as the
cure of filament-wound parts and flat panels, this benefit can already
be shown. Thinking further, the possibilities of microwave heating
are diverse. With snap-curing resins, for example, the high heat-up
ramps possible in microwave applicators could be used to cure a part in
minutes at high temperature after an infiltration lasting several hours.
While this may be a special scenario of interest for large and thick parts,
new ways of manufacturing will occur according to needs and possibilities. Microwave heating, at all events, is a huge opportunity in itself.

composites magazine 49



Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015

Cover
Edito
Point of view: The future of mass production
Contents
Companies & Business
In brief
Agenda of Events
Applications
Music - An innovative resin for the music industry
Sports & leisure - New quartz fibe prepreg material for a watch
Market
Asia - China & India: two demographic giants in very different composites markets
Industrial property - Statistical patent analysis for composite material shaping
SPECIAL JEC ASIA
15th International JEC Conferences
JEC Asia Innovation Awards Awards 2015
Education - Successful advanced composites projects in Singapore
Process - Reduction of cure cycle time through microwave curing
FEATURE
Propeller - Interchangeable motorboat propel-ler blades made of composites
Revival - The world’s fastest sailing yacht
NDTNon-destructive testing of composites benefits boat acing
Fast boat - A new generation of fast, fuel-efficient boat
Bonding - Primerless structural adhe-sives gain DNV-GL approval for marine applications
Core material - Rowing solo across the pacifi in a 24-foot boat
Research & Development
Damage - Prediction in- and out-of-plane damage in fibe-reinforced composites
Recycling - Using steam thermolysis to recycle carbon fibes from composite waste
Technology & Innovations
Thermoplastic - Easy handling, high- performance thermoplastic solutions for composites
Permeability - Why measure permeability?
Polyurethane - Polyurethane prepregs for cost-effective lightweight construction
Pipe - A new standard in multilayer composite pipe productivity
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Cover
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 2
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Edito
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Point of view: The future of mass production
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 5
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Contents
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 7
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - In brief
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 9
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 11
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Music - An innovative resin for the music industry
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 13
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Sports & leisure - New quartz fibe prepreg material for a watch
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 15
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Asia - China & India: two demographic giants in very different composites markets
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 17
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 18
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 19
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Industrial property - Statistical patent analysis for composite material shaping
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 21
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 22
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 23
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 24
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 25
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 26
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 27
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 28
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 29
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 30
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 31
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 32
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 33
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 34
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 35
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 36
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 15th International JEC Conferences
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 38
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 39
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - JEC Asia Innovation Awards Awards 2015
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 41
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 42
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 43
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 44
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 45
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Education - Successful advanced composites projects in Singapore
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 47
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 48
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Process - Reduction of cure cycle time through microwave curing
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 50
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 51
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 52
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Propeller - Interchangeable motorboat propel-ler blades made of composites
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 54
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Revival - The world’s fastest sailing yacht
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 56
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - NDTNon-destructive testing of composites benefits boat acing
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 58
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Fast boat - A new generation of fast, fuel-efficient boat
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 60
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Bonding - Primerless structural adhe-sives gain DNV-GL approval for marine applications
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Core material - Rowing solo across the pacifi in a 24-foot boat
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 63
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Damage - Prediction in- and out-of-plane damage in fibe-reinforced composites
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 65
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 66
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 67
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Recycling - Using steam thermolysis to recycle carbon fibes from composite waste
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 69
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 70
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 71
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Thermoplastic - Easy handling, high- performance thermoplastic solutions for composites
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 73
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 74
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Permeability - Why measure permeability?
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 76
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 77
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Polyurethane - Polyurethane prepregs for cost-effective lightweight construction
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 79
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Pipe - A new standard in multilayer composite pipe productivity
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - Index
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - In the world
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 83
JEC COMPOSITES MAGAZINE - Issue #100 - Special JEC Asia - October 2015 - 84
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