JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 64

infusion
Market potential and perspective
The MTI ® system was introduced in Europe in late 2010 and could convince leading composite manufacturers in the wind energy,
aerospace, shipyard, automotive and sporting equipment industries within 3 years. In the meantime, the distribution network
covers, besides Europe, countries such as Russia, China, South Africa and even Australia and New Zealand. As a general importer
with a warehouse and distribution centre in Florida, German Advanced Composites is responsible for the American market. The
company is seeking partnerships with established American distributors. It is a huge market and the sales volume is constantly
increasing, especially with the manufacturers of high-quality composite products that are either exposed to high dynamic loads
or characterized by a perfect cosmetic carbon fibre finish. Some of these manufacturers are recognized as being in the Top 10 in
their particular market segment and are willing to stay on top through further innovation within their production processes. The
MTI® system makes a decisive contribution to support this approach.

management and system pressure which,
in turn, affects the void content and fibre
volume.

The vacuum infusion process
One of the most important elements
when producing high-quality vacuum
infusion parts is to control the compaction of the preform during the infusion
process. In order to understand the
physics behind net compaction, fibre
volume, and the effects it has on the quality of the finished composite product,
we need to take a closer look into what
happens during the infusion process.
The driving force behind the vacuum
infusion process is a pressure differential
across the fibre preform, which pushes
the resin through the layup. Prior to resin
flow, the absolute pressure inside the
bag is uniformly low (vacuum uniformly
high). When the resin starts to flow,
the pressure inside the bag within the
filled areas approaches atmospheric
pressure because it is connected to the
atmosphere via the resin inlet tube. The
vacuum infusion process relies on the
overpressure of the outside atmosphere
to hold the preform beneath the bag
against the forming surface, the rising
pressure inside the bag pushing against
the atmospheric pressure above. The
pressure difference between the in-bag
pressure and the atmospheric pressure is
the net compaction pressure that is left to
press the fibre preform in the mould.
The lower the net compaction, the more
resin can flow into the preform. Because
of this, the layup must stay compacted in
order to achieve a high fibre volume. The
finished thickness of a layup is directly
related to its finished fibre volume. This

pressure differential varies depending
on a number of factors including the
pressure gradient affected by the permeability of the fibre reinforcement material
being infused, and the timing of clamping the resin inlet and evacuation lines.
The lower the compaction, the more
resin can flood the preform. In traditional resin infusion, this net compaction
can approach zero, resulting in a laminate
relaxation that leads to a higher thickness
and reduced fibre volume fraction.
The MTI® system aims at easily controlling the in-bag pressure through a new
item developed by DD-Compound, the
inventor of the MTI® hose. This item was
recently introduced as a world première
at the JEC Europe in Paris and is now on
sale with MTI® distributors.

A simple and
cost-effective solution
Although the industry has developed
a variety of other methods to address
the compaction and laminate relaxation
issue, the MTI® valve is touted as the
most simple and cost-effective solution,
without lengthy training or complex
procedures. Simply plug the MTI®
valve into the resin feed line and it will
control the pressure in the bagged system
by reducing the pressure within the
resin inlet tube, thus maintaining a net
compaction pressure to achieve optimal
fibre volume fraction. The valve works by
integrating a defined resistance into the
resin inlet line. This defined counterpressure is determined by a preloaded spring
pushing a ball into a spherical calotte.
Using the MTI® valve in conjunction
with the MTI® hose creates a closed
hydraulic system that is designed to be

64 jec composites magazine / No92 October - November 2014

self-regulating in terms of resin flow management, leaving less room for failure
and increasing the ability to repeatedly
achieve void-free laminates. This system
eliminates the need for complex timing
when clamping the evacuation and resin
inlet lines. As soon as the pressure in the
bagged system reaches the designed limit
of the MTI® valve, the valve shuts off the
resin flow and no further pressure rise is
possible within the bagged system.
The strictest adherence to process
control and repeatability is paramount,
especially in the manufacturing process
of aircraft components.
Russel Emanis, who was involved in
the Lockheed Martin F-22 U.S. stealth
fighter aircraft projects says, "It was that
highest level of compliance to process
control that had the biggest impact on my
commitment to process excellence. As a
composites processing engineer with over
30 years of experience, it has been my
personal mission to drive improved and
controlled processes in the manufacture
of composite materials. One of the critical
ways to drive continuous improvement
is through the use of the best equipment
and peripheral supplies which are available. To that end, I have been working
with German Advanced Composites to
combine my newly developed ProFusion™
infusion equipment with their innovative
product line. The MTI® hose, Squeezee®
line clamps and ProFusion™ equipment,
when combined, result in a highly controllable infusion processing system which is
unequalled to anything I have ever used
and which provides the most consistent
processing I have ever experienced." n
More information:
http://german-advanced-composites.com

http://www.german-advanced-composites.com

JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014