JEC COMPOSITES MAGAZINE - Issue #93 - December 2014 - 27

Process

High cycle speed moulding method
The innovation is a moulding method that
can produce thermoplastic/carbon fibre
composite sheets with a high cycle speed
(within 2 minutes). Typical thermoplastic
resins have difficulties in penetrating the
carbon fibre sheet due to their high viscosity. When the thermoplastic is pressed on
the carbon fibre mat with high viscosity,
the void space causes a loss in mechanical
properties. Additionally, it is difficult to produce a uniform thermoplastic/carbon fibre
composite as a continuous product.
The following issues were considered
important when developing the TPU and
PA thermoplastic/carbon fibre composite
sheets: control of the interfacial treatment
of the carbon fibre and thermoplastic resin,
the temperature and process used to make
the sheet, and finally the inter-diffusion phenomena between the carbon fibre and the

thermoplastic resin. This new process can
produce uniform CF composite sheets without a void space and is an effective method
for the mass production of thermoplastic/
carbon fibre composites. To make it possible
to commercialize thermoplastic/carbon
fibre products for automotive applications
and other markets, the process needs to possess a high cycle speed for the press moulding. Automotive customers need to produce
carbon fibre composites within one minute.
To answer this need, a high-frequency (HF)
press moulding technology was developed
for use with this thermoplastic sheet, and
it has been a success. The cycle time is one
minute, including press moulding and demoulding. For the past few years, the need to
be responsible and eco-friendly has emerged
as an important factor. Weight saving is one
of the methods used to reduce gas consump-

Winner: Dongsung Chemical (Republic
of Korea)

tion. The low weight and high performance
advantages of carbon fibre-reinforced
composite materials come into play here. In
addition, reprocessing and recycling are possible through the use of thermoplastic resins
instead of thermoset resins.
The commercialization stage will start
within a year or two, after more research and
development.

Automotive

Microwave curing of an CFRP acoustic cover for automotive applications

Economic and environmental drivers
have forced the composite manufacturing
industry to consider moving away from traditional oven or autoclave curing, which has
high energy costs and long cycle times that
are not suitable for large production, and to
consider alternative innovative technologies.
Microwave curing is one such technology
that potentially offers improved cycle times
and reduced energy consumption compared
to traditional techniques. Microwave processing does not involve convection heating of
the surfaces as microwave energy penetrates
directly into the material. Therefore, heat is
distributed evenly, even within thick materials, in a short time. It has been shown that
cycle times can be reduced by 50% or more
compared to autoclave moulding.
An engine acoustic cover incorporating
complex surface details uncommon in typical carbon aerospace components has been
successfully manufactured using microwave
curing. The process demonstrated a reduction of curing time and energy consump-

tion up to 30% compared to traditional
convection heating techniques, with further
gains expected after additional research and
optimization. Refinements were made to the
layup, bagging, shielding of fibres and consumable arrangements, which resulted in the
final component exhibiting properties equal
to an equivalent oven-cured one. This is
considered a big step in the development of
microwave curing and highlights the unique
skills developed. In addition to the engine
acoustic cover, flat plates were cured in the
microwave for mechanical and chemical
analysis of the composite material as compared to plates cured in an autoclave. Similarly,
the mechanical test results show less than
10% difference between the microwave-cured coupons and the autoclave-cured coupons. Curing the engine acoustic cover by
microwave is one of the most difficult tasks
in the manufacturing process since the shape
of the cover is quite complex. No companies
in the composite industry have tackled this
challenge so far.
The engine acoustic cover protects the en-

Winner: KC Tech (Republic of Korea)
Partnership Network: Advanced Manufacturing Research Centre with Boeing
(UK), Ssangyong Motor Co., Ltd. (Republic of Korea)

gine and helps provide thermal and acoustic
insulation while driving. Lightweight
carbon fibre reinforced composite materials
demonstrated excellent thermal resistance,
noise and vibration absorption, weight
saving and durability under high temperatures. In addition, the manufactured
composite engine covers will be more
environmentally friendly and have better
mechanical properties, lower weight and less
noise leakage. These features will make them
more attractive to the automotive markets.

No93 December 2014 /

jec composites magazine 27

JEC COMPOSITES MAGAZINE - Issue #93 - December 2014

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #93 - December 2014